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[Display omitted] • Thin copper films (20 nm) were deposited via thermal evaporation, with variations in substrate temperature (T s = RT, 330 K, and 390 K). • Films deposited at 330 K exhibited the smallest percolation thickness (12 nm) and aging rates due to their compact morphology, showcasing lower surface roughness (δ) and correlation length (ξ). • Immersion of the films in a dodecanethiol solution (1 mM) in ethanol resulted in significant resistance increment, ranging from 0.1 % to 0.4 %. • By depositing a chromium surfactant layer, the impact of the electron-surface scattering mechanism on resistivity was amplified, leading to a resistance increase of up to 1.2% due to thiols adsorption. • The negatively charged S-head of the adsorbed thiols on the copper oxide surface, altering the charge balance below the Cu 2 O/Cu interface, enhancing the electrical resistance. The impact of thiol adsorption on thin copper films, covered with a copper oxide layer, was investigated using electrical resistance measurements at various stages: during film growth, aging, exposure to air, and immersion in thiol solutions. Thin copper films (20 nm) were thermally evaporated, with variations in substrate temperature (RT, 330 and 390 K). Films deposited at 330 K exhibited the smallest percolation thickness and aging rates due to their compact morphology, showcasing lower surface roughness and correlation length. Exposure to air led to the formation of a Cu 2 O layer on the film surface. Subsequent immersion in a dodecanethiol solution in ethanol resulted in a resistance increase, ranging from 0.1 % to 0.4 %. This change was dependent on the substrate temperature, with the largest difference observed at 330 K. This observation suggests that samples grown at this temperature exhibited the highest electron-surface scattering. Moreover, by depositing a chromium surfactant layer, the impact of this scattering mechanism was amplified, leading to a resistance increase of up to 1.2 %. Mayadas-Shatzkes theory provided a good description of these resistance changes. The negatively charged S-head of the adsorbed thiols alters the electric field experienced by conduction electrons in the Cu 2 O/Cu interface, modifying the electron-surface scattering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Utilizing a pretreatment process that incorporated sandblasting, hot acid pickling, and strike nickel plating, the obtained Ni-P coating demonstrated outstanding bonding strength with the substrate, measuring 75.8 N. • A reduction in surface roughness facilitated the solder wetting while coating crystallization hindered wetting. • After undergoing 80 thermal shock cycles, no spalling or bubbling occurred on the surface of the as-plated and heat-treated Ni-P coating. W-Cu is extensively utilized as an exceptional heat sink material in high-power electronic devices. During the electronic packaging process, the surface of W-Cu demands plating with Ni or Au layers to protect the substrate and improve solderability. To enhance the bonding strength between the Ni-P coating and the W-Cu substrate, this work focused on exploring the pretreatment process for electroless nickel plating on W-Cu, with the goal of achieving a highly adhesive Ni-P coating. The effect of heat treatment on the Ni-P coating and the wetting of AgCu solder on the coating was investigated, and the growth mechanism of the Ni-P coating on the W-Cu surface was summarized. Utilizing a pretreatment process that incorporated sandblasting, hot acid pickling, and strike nickel plating. A uniform and dense strike nickel layer was obtained when pre-plated for 6 min at a current density of 3.6 A/dm2. Subsequently, the surface cells of the Ni-P coating attained through electroless plating were tightly bonded and fine, possessing optimal crystallinity. The Ni-P coating demonstrated outstanding bonding strength with the substrate, measuring 75.8 N, which increased to 83.7 N after a two-hour heat treatment at 200 °C. In the wettability experiment of the Ni-P coating, a reduction in surface roughness facilitated the solder wetting while coating crystallization hindered wetting. After undergoing 80 thermal shock cycles, no spalling or bubbling occurred on the surface of the as-plated and heat-treated Ni-P coating, indicating that the fabricated coating exhibited superb adhesion. This study addressed the lack of research on the pretreatment process of electroless nickel plating on the W-Cu surface, serving as a reference for electroless nickel plating on W-Cu. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel stress-assisted nano-cutting simulation method is proposed. • An atomic flow vortex during stress-assisted nano-cutting is observed. • The material removal efficiency is enhanced as the pre-strain increases. • The selection of optimal pre-strain aligns with the minimum friction coefficient. • The selection of optimal pre-strain remains unaffected by nano-cutting depth. The high-performance manufacturing of hard-brittle materials by single-point diamond turning (SPDT) is a very active and challenging research area. The stress-assisted nano-cutting is a promising method for improving the machinability of hard-brittle materials. However, the simulation results in the existing stress-assisted nano-cutting model would contradict the actual condition due to the pre-stress being released before tool entry into the workpiece. A modified stress-assisted nano-cutting model with a virtual boundary between the workpiece and tool is proposed for the first time in this paper to investigate the nano-cutting process of GaAs material under different external stresses. The emergence of an atomic flow vortex during stress-assisted nano-cutting significantly enhances the quality of the machined surface, leading to a substantial reduction in both machined surface roughness (34.4 %) and subsurface damage (56.2 %), compared to the normal nano-cutting. By evaluating surface roughness, subsurface damage depth, morphological accuracy, cutting force, and removal efficiency, a pre-strain of 0.06 is determined to be the optimal pre-strain for stress-assisted nano-cutting. Moreover, the selection of optimal pre-strain remains unaffected by variations in the nano-cutting depth. TEM results demonstrate that the nano-cutting mechanism elucidated by the MD analysis accurately reflects the genuine deformation of the GaAs material. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel polishing slurry was developed by using green and biodegradable additives. • The mechanism of this novel green polishing slurry in sapphire polishing was investigated. • Ultra-precision, high-efficiency, and pollution-free polishing of sapphire wafer was achieved. • Material removal modeling of this novel polishing slurry was established. Enhancing the interfacial reactivity of polishing slurry is crucial for improving the polishing efficiency and surface quality of sapphire wafers. In this study, a novel green polishing slurry was developed, comprising aminomethyl propanol, xylitol, highly active silica, and deionized water. The processing quality and removal mechanism of this novel green polishing slurry on semi-solid flexible polishing were investigated to achieve ultra-precision, high-efficiency, and environmentally friendly polishing of sapphire wafers. Experimental results demonstrated that the novel green polishing slurry reduced surface roughness by 12.5% and increased the material removal rate by 71.3% compared with traditional polishing slurry. Various analytical techniques, including wear debris analysis, molecular simulation, infrared detection, electrochemical testing, and physical phase detection, were utilized to explore the material removal mechanism. The findings indicated that aminomethyl propanol promotes chemical reactions between the green polishing slurry and sapphire wafers, leading to the conversion of the intermediate product Al(OH) 3 to Al (OH) 4 -. In addition, the complexation reaction between xylitol and Al (OH) 4 - ions during polishing was found to accelerate the removal of surface materials from sapphire wafers, resulting in improved polishing efficiency and surface quality. [ABSTRACT FROM AUTHOR]

Among neuromorphic devices, resistive random-access memory (RRAM) is considered one of the promising blocks in artificial intelligence technology for its simple structure and ability of stimuli history memorization. However, the stochasticity derived from its random nature of conductive filaments is one of the main obstacles to overcome for the introduction of RRAM into neuromorphic engineering. To address this issue, as an approach to optimize the electrode, surface roughness engineering is introduced to improve the cycle-to-cycle reliability of zinc oxide-based memristors. By the self-micro-masking effect of SF 6 plasma treatment for Si etching, bare p + -Si substrate was roughened up to 17.36 nm root-mean-square (rms) roughness. Improved temporal variability of resistance states of the ZnO memristor fabricated on substrates with different roughnesses was observed. Eventually, on the basis of data obtained from electrical characteristic measurement, the simulated image recognition accuracy of the device with a roughened surface showed improved results as well from 76.58 % to 84.59 %. [Display omitted] • Effect of Si substrate-roughening plasma on oxide RRAM is investigated. • Pt/ZnO/roughed-Si RRAMs demonstrated improved temporal variability. • Image recognition accuracy was improved on the modified device-based simulation. • Roughened electrode surfaces supplied effective pathways for conductive filaments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Boron doping affects the surface morphology and roughness of the exfoliated silicon samples. • Boron doping affects the aggregation of damage, the width of the damage band, the size and density of stick cavities under the same implantation and annealing parameters. • The surface modification after exfoliation is related to the diffusion of hydrogen and the defect evolution at lower temperatures. Ultra-thin silicons can be obtained using SMART CUT technology, but there is a lack of systematic research on the effect of boron doping. This paper reports the effects of boron doping on surface modification and defect evolution. Monocrystalline silicon samples with different concentrations of boron doping were implanted to 3.5 × 1017H+/cm2 using a 1.52 MeV High Intensity Proton Implanter (HIPI) and annealed at 300, 400, and 550 ℃. The annealed samples were analyzed by non-contact optical profilometry, Raman spectroscopy, SEM, and TEM. The results show that appropriate boron doping can reduce the surface roughness of the exfoliated samples; excessive boron doping leads to a significant increase in surface roughness (∼525 nm) and produces a step-like morphology. Boron doping leads to changes in the type, concentration and dissociation temperature of hydrogenated defects during implantation. These changes result in the width of damage band changes vary with doping concentration. The density and diameter of the hydrogenated extended defects also changed, which results in the surface modification of samples, such as the change of the surface morphology and substrate roughness. In the end of the paper, the paper discusses the correlation between surface morphology and internal damage for different concentrations of boron doping. [ABSTRACT FROM AUTHOR]

[Display omitted] • A green and environmentally friendly porous spherical self-assembled cerium oxide particle doped with La, Pr, and Nd was synthesized. • The abrasives exhibit flexible and high chemical activity. • The Ce3+ content and oxygen vacancies of the La/Pr/Nd-doped CeO 2 particles were analyzed using XPS, XANES, H 2 -TPR, and DFT. • The synthesized doped porous spherical self-assembled cerium oxide particles improved the removal rate and surface roughness of SiO 2 film. With the linewidth of integrated circuits has progressively narrowed, imposing higher demands on the chemical mechanical polishing (CMP) process. Cerium oxide nanoparticles are widely used as abrasives in CMP, with their physical structure and the surface content of Ce3+ ions and oxygen vacancies directly affecting their CMP performance. Here in, we synthesized La/Pr/Nd doped CeO 2 with the porous self-assembled spherical structures. Doping with La/Pr/Nd reduced the grain size of cerium oxide, increased its specific surface area, decreased the pore size, and increased the pore volume. HR-TEM analysis shows that the porous self-assembled spherical CeO 2 primarily exposes the (111) crystal facet. Additionally, the density functional theory (DFT) calculation, XPS, H 2 -TPR and XANES analyses shown that doping of La/Pr/Nd facilitated the formation of oxygen vacancies and increased the Ce3+ content on the (111) crystal facet of the CeO 2. La atoms are more likely to stabilize on the CeO 2 (111) surface compared to Pr and Nd atoms. The CMP results indicated that, The La-CeO 2 exhibited a higher MRR of 338 ± 7.54 nm/min, which is a 35 % increase compared to p-CeO 2 , and achieved superior surface roughness (Ra = 0.201 ± 0.010 nm). [ABSTRACT FROM AUTHOR]

Efficient access to non-damaging and atomic-scale surfaces of GaN (0001) by grinding-ICP etching-CMP. [Display omitted] • Efficient access to non-damaging GaN (0001) by ICP-etching and CMP. • The GaN surface roughness obtained by ICP etching-CMP is less than 0.2 nm. • ICP etching-CMP processing time reduced to 1.5 h. • ICP etching and CMP proved to be non-destructive processing methods. As third-generation semiconductors advance, gallium nitride (GaN)-based devices are gaining significant attention. However, the processing of GaN substrates directly affects device performance. This paper proposes an ICP etching-chemical–mechanical polishing (CMP) strategy to efficiently produce GaN single-crystal substrates with non-destructive, atomic-level surfaces. The process time is significantly reduced from 15 h to 1.5 h. The wet oxidation reaction during CMP eliminates impurities and defects from dry etching. FIB-STEM tests confirm that this method is non-destructive, as the ICP technique enables isotropic etching, and CMP introduces no new damage to the substrate. This approach enhances the productivity of large-size GaN single-crystal substrates, promoting their broader application in laser displays, RF devices, and power electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adding diamond abrasive improved polishing properties of single ceria abrasive. • Materials removal rate and surface flatness were improved simultaneously. • An amorphous reaction layer mainly composed of Ce-O-Si was observed directly. • Formation and removal of reaction layer reached a dynamic equilibrium in CMP process. Chemical mechanical polishing (CMP) is currently the most widely used method for material removal and surface planarization of glass. An environmentally friendly method of improving polishing performance by using a mixed abrasive slurry of ceria and diamond was proposed in this study. The results of polishing experiments showed that compared with single ceria abrasive, the materials removal rate (MRR) of the mixed abrasive slurry increased from 82.7 nm/min to 109.6 nm/min, while the surface roughness (Ra) decreased from 26.4 nm to 0.6 nm after polishing. An amorphous reaction layer formed during the CMP process was observed directly using transmission electron microscopy. Thermodynamic analysis was conducted to investigate the interfacial chemical reactions during the polishing process. A model was proposed to describe the mechanism of the materials removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chloride salt erosion changes asphalt's microstructure and mechanical properties. • Asphalt's roughness increases with chloride concentration and erosion duration. • Significant reduction in nano adhesion under varied chloride conditions observed. • Young's modulus of asphalt shows a marked increase with erosion duration. To explore the impact of chloride salt erosion on the microstructure and micromechanical properties of asphalt, this study utilizes the atomic force microscopy (AFM) to examine the evolution of micromorphology, surface roughness, adhesion, and Young's modulus of asphalt in dry conditions, under various chloride salt concentrations, and after different erosion times. The results indicate significant changes in the microtopography of the asphalt surface due to chloride salt erosion, characterized by the reorganization of nanoscale protrusions and white spots. This results in a decrease in their quantity and total area, while the average area increased, demonstrating a trend of phase dispersion and aggregation. Erosion increased the surface roughness of the asphalt and significantly altered its mechanical properties. Specifically, with an increase in chloride salt concentration, the average roughness (R a) of asphalt, after one day of erosion relative to its dry state, increased by 7.99 %, 33.06 %, and 52.55 %, respectively. As the erosion time was extended, at a 2.5 % chloride salt concentration, the growth rate of R a reached 33.06 %, 54.68 %, and 67.22 %, respectively. A declining trend in nano adhesion was observed, indicating internal structural damage and reduced durability, while Young's modulus significantly increased, suggesting a densification of the asphalt matrix and enhanced rigidity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The introduction of potassium bitartrate (KBT) into the TiO 2 film improves TiO 2 surface smoothness and charge transport, reducing recombination centers in PSCs. • KBT in TiO 2 ETLs enhances PSC morphology, reduces interface defects, and improves energy alignment, leading to higher efficiency and stability. • PSCs with KBT show a significant efficiency increase to 23.35 % and maintain over 80 % efficiency after 800 h. The performance of perovskite solar cells (PSCs) has rapidly improved, largely due to advancements in mitigating inherent defects and enhancing interface carrier transport properties. Herein, we provide a facile method to improve the morphology of TiO 2 ETLs, suppress defects at interface, and tailor energy level alignment to enhance carrier separation and extraction efficiency by introducing potassium bitartrate (KBT) into the TiO 2 electron transport layers (ETLs), achieving high-efficiency and stable PSCs. KBT molecules can enhance the surface smoothness of TiO 2 ETLs, resulting in denser and more uniform perovskite films. In addition, the carboxyl groups, hydroxyl groups, and potassium cations containing in KBT improve charge transport efficiency at TiO 2 /perovskite interface by reducing non-radiative recombination centers in TiO 2 and perovskite bottom as well as improving energy level matching. As a result, the target PSC exhibits an obvious improvement in performance with a champion efficiency of 23.35 %, which is greatly improved relative to the control (21.66 %). The long-term operational stability is also remarkably enhanced, after 800 h MPPT, PSCs with KBT remain over 80 % of its initial efficiency. PSCs with KBT-doped ETLs exhibit increased efficiency and stability, highlighting potential of KBT as an interface engineering tool for enhancing PSCs performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • We investigated CO activity dependence on Si surface carbonization reaction. • SiC nuclei were formed during the initial stage even under SiO 2 -stable conditions. • Carbonization proceeds based on carbonization driving force after nucleation. • SiC film was always oriented to Si(100) and Si(111). • SiC(111) or (110) was formed on Si(110) under higher or lower CO activity. SiC thin films formed by Si surface carbonization can be used as buffer layers for the heteroepitaxial growth of nitride semiconductors. We propose a Si surface carbonization method using CO gas. In this study, we investigate the dependence on CO activity (a CO) of the carbonization of Si(100), Si(110), and Si(111). The Si surface reacts with the CO molecules to form SiC nuclei during the initial carbonization stage. Following nucleation, carbonization proceeded based on the thermodynamic carbonization driving force. At a lower a CO with a larger driving force but smaller nucleation density, a thicker SiC film comprising larger grains with higher crystal coherency was formed, whereas the roughness of the SiC surface and SiC/Si interface is larger. Furthermore, voids with larger sizes and densities were formed at the SiC/Si interface. The thickness, grain size, and crystal coherency of the SiC film were on Si(110)≳Si(111)≫Si(100). All the SiC films were singly oriented. The SiC films were oriented to Si(100) and Si(111), regardless of carbonization conditions. In contrast, SiC(111) or SiC(110) was formed on Si(110) carbonized at lower and higher a CO , respectively, as determined by the SiC formation rate, structural stability of the plane, and lattice mismatch. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-stable CsPbBr 3 NCs-acrylate films was synthesized via a triple passivation strategy. • Poly@SiPNCs film exhibited high hydrophobicity (141.5 ± 1.9°). • Poly@SiPNCs film exhibited improved stabilities to water and UV light. • This work will boost a large-scale preparation of stable NCs-based films as backlight display. To improve the stability of CsPbBr 3 nanocrystals (NCs), triple protection strategies were performed to obtain the ultra-stable films, including fluorinated hydrophobic film surface, polymer coating and silica encapsulation. CsPbBr 3 QDs@SiO 2 nanoparticles (SiPNCs) were prepared with well-dispersed NCs (8 nm) within acrylate-modified silica-shell. Polymer@SiPNCs (poly@SiPNCs) films were prepared by copolymerization of methyl methacrylate (MMA), 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl methacrylate (DFHM) and SiPNCs under ultraviolet (UV) light. Compared to CsPbBr 3 NCs solution, SiPNCs solution had well maintained light absorption and emission wavelengths of ∼509 nm and ∼522 nm respectively. High SiPNCs content resulted in enhanced micro/nano structure and increased roughness on the surface of poly@SiPNCs film. With increasing SiPNCs content, water contact angles (WCAs) of poly@SiPNCs films reached 126 ± 2.4°, 137.3 ± 1.3° and 141.5 ± 1.9° respectively. This fabricated poly@SiPNCs film exhibited much improved stabilities to water and UV light, even after 90 days of water immersion and 120 h of UV irradiation. White light-emitting-diode (LED) device emitted bright pure white light. This work will boost a large-scale preparation of stable QDs films as backlight display. [ABSTRACT FROM AUTHOR]

We obtained three types of particles with different surface characteristics, including solid silica with smooth surface and no surface group (SiO 2), mesoporous silica with rough surface and no surface group (M−SiO 2) and mesoporous silica with rough surface and surface silicon hydroxyl groups (M−SiO 2 (–OH)). Compared with SiO 2 , M−SiO 2 and M−SiO 2 (–OH) have higher friction between particles due to rough surfaces, and there is adhesion force between M−SiO 2 (–OH) particles due to the presence of hydroxyl groups on the surface. The schematic phase diagram of the ϕ - γ ̇ for three types of particles shows the difference of rheological property. [Display omitted] • The influence of surface characteristics on the suspensions was explored. • The roles of friction and adhesion forces on the suspensions were evaluated. • The ϕ - γ ̇ phase diagram was present to demonstrate the rheological difference. The surface characteristic of suspended nanoparticle is an extremely important property for the non-Newtonian behavior of shear thickening suspensions. Easy access to distinct surface characteristics and a deep understanding of the role of friction and adhesion forces remains challenging yet critical to study the suspension performance. In this work, by synthesizing mesoporous silica with different surface roughness and groups, the influence of surface characteristics on the non-Newtonian behavior of suspension is comprehensively explored. The results show that the suspensions containing particles with rough surface and hydroxyl groups on the surface have higher shear thickening power, lower critical shear rate, lower discontinuous shear thickening transition fraction and lower jamming fraction. Furthermore, the test of the first normal stress difference N 1 shows that the interparticle friction and adhesion both reduce the critical volume fraction of the transition from fluid lubrication dominance to frictional contact dominance in the suspension. This finding deepens the understanding of phase transformation mechanism, and open an approach to accelerate the advanced shear thickening suspensions design for next-generation intelligent materials. [ABSTRACT FROM AUTHOR]

1. The Ir a Hf b Al c alloy thin films were deposited by Direct Current Magnetron Sputtering (DC-MS). 2. We for the first time prepared Ir a Hf b Al c alloy thin films with a preferred (111) orientation substitution solid solution, which have the advantages of mechanical properties and oxidation resistance. 3. The mechanical properties of the Ir a Hf b Al c alloy films were significantly improved over the previous ones, with maximum hardness (H) and modulus of elasticity (E) exceeding 20 GPa and 330 GPa, respectively. 4. The catalytic activity of Ir in Ir a Hf b Al c films is effectively reduced. The volatilization temperature of the films is increased and the overall oxidation resistance is substantially improved. [Display omitted] • The Ir a Hf b Al c alloy thin films with a preferred (111) orientation substitution solid solution were first prepared by us for the first time. It has the advantages of mechanical properties and oxidation resistance. • The mechanical properties of the Ir a Hf b Al c alloy films were significantly improved over the previous ones. The minimum surface roughness (Ra) value of the IraHfbAlc alloy films was 0.7 nm, while the maximum hardness (H) and elastic modulus (E) exceeded 20 GPa and 330 GPa, respectively. • The oxidized volatility of the Ir in the films was only 0.11 μm/h at 1300 °C (lower than most of the previously reported values, such as 0.5 μm/h). The oxidation rate was slowed down by 50 % compared to the previous one, which greatly improved the lifetime of the film. • Moreover, the modified Ir a Hf b Al c alloy thin films reduce the catalytic activity of Ir metal, reduces the thermal effect and increases the volatilization temperature. • Detailed analysis of microscopic phenomena reveals the presence of crystal-like order (CLO) in thin films, solving the mystery of improved oxidation resistance and mechanical properties. Improving oxidation resistance has long been a challenge for hot end components in high temperature environments. We have fabricated a series of Ir a Hf b Al c (at. %) alloy thin films by multi-targeted direct current magnetron sputtering (DC-MS) and have thoroughly investigated the microscopic mechanism of the films. More importantly, we for the first time prepared Ir a Hf b Al c alloy thin films with a preferred (111) orientation substitution solid solution, which exhibits excellent mechanical properties and oxidation resistance. The minimum surface roughness (R a) value of the Ir a Hf b Al c alloy films was 0.7 nm, while the maximum hardness (H) and elastic modulus (E) exceeded 20 GPa and 330 GPa, respectively. The oxidized volatility of the Ir in the films was only 0.11 μm/h at 1300 °C (lower than most previously reported values, such as 0.5 μm/h), which greatly improved the lifetime of the film. Confirmation that lattice distortion induces the refinement of crystal-like order (CLO) in thin films, and solves the mystery of enhanced oxidation resistance. The findings provide important insights into the design of Ir-containing alloy coatings and offer new ideas in the field of high-temperature protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel green chemical mechanical polishing was developed. • Surface roughness Sa of 0.179 nm is achieved. • Chemical mechanical polishing mechanism is elucidated. Traditional chemical mechanical polishing (CMP) normally employs noxious slurries, leading to pollution to the environment. It is a challenge to achieve atomic surfaces of nickel (Ni) alloy using green CMP. To overcome this challenge, a novel green CMP was developed, including composite abrasives of ceria and silica, mandelic acid, hydrogen peroxide and deionized water. Using the developed green CMP, atomic surface with surface roughness Sa of 0.179 nm was achieved, under a scanning area of 50 × 50 μm2. Electrochemical tests indicate that the developed slurry has effective corrosion ability on Ni alloy. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy reveal that the Ni alloy was oxidized by hydrogen peroxide, forming oxides of Ni, chromium (Cr) and molybdenum (Mo). Cr and Mo oxides demonstrated better stability in mandelic acid, while Ni oxides reacted with hydrogen ions and produced Ni2+ and Ni3+ ions. The ions chelated with mandelic acid. Finally, the generated oxides and reaction products were removed by abrasives and a polishing pad under chemical and mechanical balanced functions. The developed green CMP paves a new avenue to obtain atomic surface of a Ni alloy for the possible applications of high-performance components in aerospace industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Controllable roughening of the GaN surface through an experimental approach. • GaN samples were annealed at 1200 °C under N2 ambient. • Surface roughness is controlled by the number of annealing cycles. • Ga-rich GaN nanoparticles formed at the surface with no change in the dislocation density. • Compressive stress decreases, resulting in enhanced optical properties. GaN-based semiconductor structures have been widely used in photonic, electronic, and optoelectronic devices. However, due to the lack of lattice-matched substrates for GaN, several schemes related to material growth and device structure, including surface roughening, have been proposed to improve the efficiency of GaN-based devices. In our work, we developed an experimental approach to achieving a controllable roughening of the GaN epilayer surface by thermal post-annealing. The degree of surface roughness, i.e., nanometric modification, is controlled by the number of annealing cycles. The samples were annealed at 1200 °C under N 2 ambient. Under this condition, the first stage of GaN decomposition occurs. This annealing process led to the formation of Ga-rich GaN nanoparticles at the film surface with no significant change in the dislocation density. Furthermore, this treatment greatly decreases the compressive stress degree, resulting in a considerable improvement in the optical properties of the GaN samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • PCL/CS nanofibers were electrospun, mimicking the aligned myocardial extracellular matrix. • Ar and N 2 DBD plasma treatments incorporated surface polar groups, enhancing cell adhesion. • Plasma-treated aligned fibers induced cardiomyocyte elongation and anisotropy. • The cell elongation was less pronounced on GeltrexTM-coated nanofibers. • Increased sarcomere distance and organization suggest cardiomyocyte maturation. Pluripotent stem cell (PSC)-derived cardiomyocytes offer vast potential in heart failure therapy, yet their immaturity poses challenges. To solve this issue, a multifaceted approach combining exclusive biochemical/topographical cues in the design of substrates mimicking the cardiac extracellular matrix was followed. Firstly, polycaprolactone (PCL)/chitosan nanofibers were electrospun in a random and aligned fashion, thus forming myocardium-like constructs. The scaffolds were then subjected to Ar and N 2 dielectric barrier discharge treatments, thus further improving their surface properties. The Ar plasma incorporated oxygen-containing functionalities onto the nanofibers surface with an additional implantation of nitrogen-containing groups upon N 2 plasma treatment, which both enhanced fibers' wettability. No topographical/dimensional damages were detected post-plasma treatments, except for a slight decrease in the surface roughness of the aligned nanofibers, which led to a decrease in their tensile stress. Both plasmas significantly enhanced the adhesion of PSC-derived cardiomyocytes that displayed more circular versus highly elongated body/nucleus morphologies on random versus aligned nanofibers, respectively. Interestingly, the cell alignment was less pronounced on GeltrexTM-coated nanofibers. Furthermore, increased sarcomere distance and organization were observed on aligned plasma-treated nanofibers, suggesting an enhanced cell maturation. Overall, PCL/chitosan nanofibers with aligned orientation and plasma-induced surface chemistry hold promise in cardiac tissue engineering applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simulation of SiN x deposition based on molecular dynamics (MD) simulation provides a more convenient and clear solution. • A quick and accurate method basing on Alpha-shapes was proposed to extract surface atoms. Experimental results also confirms that the proposed surface roughness evaluation approach is better than the conventional one. • The simulation results confirm that the substrate temperature during deposition has an effect on the adsorption and atomic drift rate of the substrate, which in turn affects the surface morphology of the film. Due to the limitations of the characterization approaches and the relative complex and expensive characteristics of CVD method itself, experimental-based studies are limited, and simulation of SiN x deposition based on molecular dynamics (MD) simulation provides a more convenient and clear solution. In this work, Tersoff potential function containing the interatomic potential for two-body and three-body interactions was utilized to simulate of the deposition process for SiN x thin films by the PECVD. A quick and accurate method basing on Alpha-shapes was proposed to extract surface atoms and the surface roughness of the thin film samples at substrate temperatures of 353, 493, and 653 K were found to be 0.804, 0.794, and 0.721 nm respectively. By analyzing the radial distribution function, it can get that there are small changes in the Si-Si and Si-N bonds at three temperatures. We also found the diffusion phenomenon at the interface, and the atomic diffusion phenomenon at the substrate interface makes the phenomenon of elemental mutation at the interface less rapid. The simulation results confirm that the substrate temperature during deposition has an effect on the adsorption and atomic drift rate of the substrate, which in turn affects the surface morphology of the film. [ABSTRACT FROM AUTHOR]

It touches on an atomic level GaN surface with smooth surface and near non-damaged layer was obtained by weakly alkaline ZrO 2 –SiO 2 based slurry, the reasons for the increase of GaN material removal rate and the formation of surface atomic step morphology were deeply studied. [Display omitted] • An atomic level GaN surface was obtained by weakly alkaline ZrO 2 –SiO 2 based slurry. • The surface and properties of Ga-faced GaN crystal before and after CMP were studied by various testing methods. • The principle of GaN material removal is explained from the perspective of mechanical action and chemical oxidation. A remarkable improvement in the chemical–mechanical polishing (CMP) of GaN using a weakly alkaline ZrO 2 –SiO 2 based slurry is described in detail, and an almost complete atomic step-platform structure with a surface roughness (Ra) of 0.059 nm is obtained. ZrO 2 nanoparticles were added to the CMP slurry to replace part of the SiO 2 to obtain a higher removal rate. When the content of ZrO 2 reaches 0.5 wt%, the material removal rate of GaN is increased by 47.5 % compared with that of SiO 2 with equal content, which significantly improves the material removal rate (MRR) of GaN, and does not destroy the atomic ladder-platform structure. In addition, we also investigate the causes of the formation of atomic ladder-terrace morphology on Ga-face, and describe the removal mechanism of materials in CMP process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ultra-precision diamond sculpturing process is employed to machine the high-quality microlens array on the monocrystalline silicon surface. • Rapid thermal annealing greatly improves the surface quality of microlens arrays and the surface roughness S a reduces to 1.6 nm. • Rapid thermal annealing effectively heals the subsurface defects of the machined microlens array when the annealing temperature is above 600 °C. • The molecular dynamics simulation reveals that the healing mechanism of rapid thermal annealing is the solid phase epitaxy. Microstructure arrays, such as microlens arrays, play a significant role in optical systems, biomedical imaging, and telecommunications. However, the machining-induced subsurface defects deteriorate their performance and functionality. To address this issue, this study proposes a rapid thermal annealing method to heal the subsurface defects using different temperatures ranging from 200 °C to 1000 °C in a vacuum. Firstly, the ultra-precision diamond sculpturing process is employed to machine the high-quality microlens array on the monocrystalline silicon surface. Then, the effects of the rapid thermal annealing on the microlens array surface, such as surface roughness and subsurface defect, are comprehensively investigated. Experimental results show that the annealing temperature of >600 °C contributes to the decrease in surface roughness and subsurface defect. Furthermore, to reveal the healing mechanism, a molecular dynamics simulation of rapid thermal annealing is performed by controlling the bulk temperature of machined monocrystalline silicon from 500 K to 1300 K. The simulation results show that recrystallization always occurred on the interface between the amorphous layer and monocrystalline silicon substrate and the healing mechanism should be solid phase epitaxy rather than random nucleation. The research findings would contribute to fabricating the defect-free optical lens in the industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti-Zr-V films on OFC and Si substrate exhibit different scratch failure mechanisms. • Effects of thermal cycling on adhesion properties vary with different substrates. • Thermal cycling alters the surface morphology of Ti-Zr-V films. • No phase transition or crystallization occurs during the thermal cycling. Non-evaporable getter films are essential to obtain the ultra-high vacuum environments for the modern accelerators. However, regular thermal activation of the NEG films is required to maintain their pumping capacity. The thermal activation rises the risk of deteriorating the film/substrate adhesion, which, unfortunately, has been overlooked. In the present work, ternary Ti-Zr-V films were deposited by DC magnetron sputtering on oxygen free copper (OFC) and Si substrates. The effect of thermal cycling on the microstructure and adhesion strength of the thin films were characterized. The results indicate that thermal cycling induce an increased surface roughness due to coarsening of the particle size. Contrary effect is imposed on the adhesion strength of the NEG film deposited on the OFC substrate as compared with that on the Si substrate. After thermal cycling, the scratching critical load of the Ti-Zr-V film on OFC decreases from 0.14 N to 0.06 N while those on Si substrate increased by tenfold from 0.56 N to 5.79 N. The current work is insightful on long-term maintenance of the NEG coated chambers from an angle different from the commonly emphasized pumping capabilities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Randomly rough PET substrates are modeled by MD simulations. • Adhesion process and final state of graphene on rough PET surfaces are investigated. • Graphene freely attached to the rough PET surfaces is nearly strainless. • SLBT is performed to measure the adhesion energy of graphene/PET substrate. • Non-conformal state caused by high surface roughness increases the blister instability. In this work, molecular dynamics (MD) simulations are performed to create a series of polyethylene terephthalate (PET) substrates with random roughness, and the morphological characteristics and interfacial bonding of graphene on the real rough PET surface are first simulated. The results show that the interfacial mechanical behavior of graphene freely adhered to the PET roughness is influenced by the surface profile. Besides causing the non-conformal contact, the rough surface hinders the propagation of bending waves from the graphene corner regions during the adhesion and weakens their overlap. The increased surface roughness weakens interfacial adhesion and inhibits interfacial sliding, leading to the formation of larger morphological defects such as wrinkles. Furthermore, the measurement of the interfacial adhesion energy of graphene/PET substrate is achieved by the shaft loaded blister test (SLBT), which for the first time is used to simulate the interfacial debonding of graphene on rough PET surfaces. For low surface roughness, interfacial adhesion dominates the debonding behavior and the blister boundary preferentially extends along the interfacial defect area. For high surface roughness, the increasingly serious non-conformal contact makes the blister more likely to instability and enter the stage where normal and shear interactions are coupled. [ABSTRACT FROM AUTHOR]

[Display omitted] • Overcome the fluidity deficiency of Cr 2 AlC powder in plasma spraying by suspension feeding. • Achieve high Cr 2 AlC phase retention by constructing a self-protection system with water addition. • Optimize phase composition and coating quality by adjusting the spraying power. In this work, the microstructure evolution and mechanical properties of suspension plasma sprayed Cr 2 AlC coatings under different spraying powers were studied, and a self-protection model during oxidation was proposed. Due to the partial decomposition of Cr 2 AlC and its subsequent reactions with the surrounding H 2 O or O 2 at high temperatures, the sprayed coating exhibits a heat-resisting shell, composed mainly of Cr 2 Al, carbides, oxides, and graphite, wrapping the internal Cr 2 AlC core against further decomposition. In addition, with the increase of spraying power, the content of Cr 2 AlC phase and the microhardness of the coating gradually increase, while the porosity and surface roughness decrease. The results indicate that suspension plasma spraying is a promising process for preparing Cr 2 AlC coatings. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual-active-layered InGaSnO TFTs exhibit improved electrical performances. • Introducing oxygen reduces the total trap density of InGaSnO TFTs. • The oxygen vacancies and surface roughness of the InGaSnO films were reduced by oxygen flow rate. • The energy band structures of the dual-active-layer InGaSnO films were analyzed. In this study, dual-active-layer InGaSnO (IGTO) thin-film transistors (TFTs) were designed, and their electrical properties were investigated. Consequently, compared with the single-layer IGTO (pure Ar) TFTs, the dual-layer IGTO TFTs exhibited improved electrical properties, including a high field-effect mobility of 25.1 cm2 V−1 s−1, a low threshold voltage of 0.8 V, a high on/off current ratio of 1 × 108, a small subthreshold slope of 300 mV/decade, and a low off current. Additionally, the dual-layer IGTO TFTs showed superior stability for small V th shifts of −1.9 V and 1.8 V under gate bias stress test conditions. Band structure analysis indicated that a thin front layer of IGTO (pure Ar) can provide an appropriate carrier concentration (N e) near the IGTO (pure Ar)/IGTO (Ar/O 2) interface, whereas a thick layer of IGTO (Ar/O 2) can control the channel conductance and threshold voltage of IGTO TFTs. Moreover, atomic force microscopy, X-ray photoelectron spectroscopy, and Hall effect measurement results showed that the surface roughness, oxygen vacancies, N e , and total trap density of IGTO (Ar/O 2) films and TFTs were reduced by increasing the oxygen flow rate. Over all, the high performance dual-active-layer IGTO TFTs provides insights that can contribute to developing a new generation of transparent oxide thin-film electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnO pillars are fabricated by pulsed laser deposition (PLD) technique at a high substrate temperature of 700 °C. • The enhanced root-mean-square surface roughness (R r.m.s) from SPM analysis demonstrates the significant enhancement in ZnO-700 surfaces. • The PL analysis shows the highest (zinc) Zn interstitial (Z ni) and lowest oxygen vacancy (O V) concentration in ZnO-700. • The ZnO-700 sample displays a smaller static CA (98.60°) compared to ADZnO-RT (101.90°), indicating a more superhydrophilic nature. • The ZnO-700 based sample had a better sliding angle (α) of 61.65°, a maximum frictional force (F max) of 1.76 μN, a corresponding work of adhesion (W adhesion) 61.01 mN/m, and a wettability conversion rate (WCR) of 7.20 × 10−5°−1/min indicating faster sliding phenomena and a better superhydrophilic transition. The structural, optical, and superhydrophilic properties of zinc oxide (ZnO) pillars are reported by pulsed laser deposition (PLD) technique at a high substrate temperature of 700 °C. The X-ray diffraction (XRD) analysis reveals that the increased crystallite size in ZnO-700 (98.47 nm) plays an important role in promoting superhydrophilic behaviour than ADZnO-RT (57.19 nm). The root-mean-square surface roughness (R r.m.s) from scanning probe microscope (SPM) analysis demonstrates the significant enhancement in ZnO-700 surfaces. The ZnO-700 based samples show improved light absorption in the ultra-violet (UV) and visible light absorption which can boost photocatalytic activity. The photoluminescence (PL) analysis shows the highest (zinc) Zn interstitial (Zn i) and lowest oxygen vacancy (O V) concentration in ZnO-700. A static contact angle (CA) measurement was performed, where ZnO-700 sample displays a smaller static CA (98.60°) compared to ADZnO-RT (101.90°), indicating more superhydrophilic nature. The ZnO-700 based sample had a better sliding angle (α) of 61.65°, a maximum frictional force (F m a x ) of 1.76 μN, a corresponding work of adhesion (W adhesion ) 61.01 mN/m, and a wettability conversion rate (WCR) of 7.20 × 10−5°−1/min indicating fast sliding phenomena and better superhydrophilic transition. The superhydrophilic properties of ZnO-700 make it a valuable asset for smart surfaces and microfluidic devices application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanoscale roughness was fabricated by using lithography to study the particle adhesion. • Fabricated rough surface was characterized by AFM, FE-SEM, and EDX. • Contact area between the AFM probes and surfaces depends on the type of probes and fraction of roughness on surfaces. • Increasing the contact area reduced the adhesion force and improved the repulsive force. Despite substantial theoretical approaches explaining the effect of nanoscale roughness (NR) on particle deposition, experiments are rarely performed. Fabricating the sophisticated rough surfaces and obtaining the experimental data for interaction between the colloids and surfaces are crucial to understand colloidal adsorption onto the rough surfaces. We investigated the adhesion of different particle types of atomic force microscope (AFM) probes (different shapes, i.e., sphere and plateau; diameters, i.e., 2 μm–15 μm) onto smooth and rough fabricated surfaces. We successfully fabricated well-organized rough surfaces on Silicon (Si) using colloidal lithography and metal-assisted chemical etching using a cylindrical shape of constant nanoscale height and diameter. The properties of roughness (i.e., height, diameter, and fraction) were quantitatively analyzed, and the corresponding. The force-distance curves measured with the AFM revealed that, for the four types of probes, contact area varied with the surface roughness, and their adhesion forces differed accordingly. Expanding the contact area tended to increase the repulsive force possibly because of the hydration force. This study effectively devised a simplified experimental system that explains the influence of NR on particle deposition using previous theoretical data. The findings should be considered in designing NR for subsequent colloidal deposition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Subnano-scale roughness of Gradia surface was acquired by CMP. • Subsurface damage of lattice distortion was incompatible for graphite and diamond in Gradia. • Chemically reacted graphite phase was more than the diamond phase during CMP of Gradia. • Diamond phase was chemically softened to graphitic phase for rapid material removal. The novel graphite/diamond composite (Gradia) possesses semiconducting instinct characteristics with controllable resistivity. Surface finishing plays a crucial role in using Gradia. However, controlled removal of the Gradia surface is challenging because physical and chemical properties differ between the graphite and diamond components. The impact of incompatibility on the material removal of Gradia is unclear. This study employed chemical mechanical polishing (CMP) to finish the Gradia surface with K 2 FeO 4 oxidant. First, the sub-nano-scale roughness of the Gradia surface was attained by applying optimized polishing parameters. Then, the polished subsurface was examined. The incompatible graphite and diamond lattice distortion was the primary damaged mechanism rather than amorphization. The chemical reaction in CMP was analyzed with X-ray photoelectron spectroscopy and reactive molecular dynamics simulation. The carbon atoms formed a variety of chemical groups with the oxidizing of hydroxyl. The chemical activity of the graphite phase was superior to the diamond phase, leading to more types of reaction and a higher percentage of products. In the material removal stage, experimental observations and simulation analyses revealed that the diamond of sp3-carbon transformed to sp2-carbon, softened, and subsequently removed together with the graphite by abrasive scratching. [ABSTRACT FROM AUTHOR]

[Display omitted] • A superhydrophobic surface of silicone rubber was obtained by CF 4 plasma treatment method. • Effect of different times and powers of plasma process was investigated. • A contact angle of 151.3° was obtained by plasma treatment at 100 W for 7 min. • XPS results approved formation of the F-C and F-Si bands during success fluorination. • Roughness of the treated surface at 100 W for 7 min increased to 55 nm. In this paper, a superhydrophobic surface of silicone rubber was fabricated by plasma treatment method. Modification of the surface chemistry under CF 4 atmosphere at different times (3, 5, and 7 min) and powers (50, 75, and 100 W) of plasma process has been investigated. A superhydrophobic surface with contact angle of 151.3° was obtained for plasma treated sample at 100 W for 7 min. X-ray photoelectron spectroscopy (XPS) results indicated that the surface fluorination of silicone rubber increased as the time and power of plasma exposure increased. Investigation of the F 1s and Si 2p spectra approved the formation of F-C and F-Si bands. Also, the roughness of the surface increased from about 42 nm for untreated to 55 nm for treated sample (7 min at 100 W) due to the emergence of the ceramic fillers in degraded silicone rubber matrix after plasma treatment. Both of the surface fluorination and roughness increment are the reasons of superhydrophobicity properties. Examination of the hydrophobic recovery by surface contamination method indicated that a contact angle of 101° was recovered after 9 days. [ABSTRACT FROM AUTHOR]

[Display omitted] • The transparent and amphiphilic silicone-based coatings are prepared conveniently. • Significantly lower protein adhesion force and reduced protein attachment are obtained. • Excellent fouling release performance is reached. • Significant differences in the expression of adhesion proteins in mussel adhesive plaque are verified. • The main reason is that the introduction of amphiphilic materials significantly reduces the adhesion strength at the coating-fouling interface. The amphiphilic antifouling coatings are effective for inhibiting fouling adhesion. Herein, the amphiphilic coatings were prepared by introducing polyether-modified polydimethylsiloxane (PE-PDMS). Uniform morphology, high transmittance, low surface roughness and amphiphilic property were obtained. PE-PDMS appearing as interspersed chains endowed the coating with amphiphilic characteristic. The artificial seawater promoted the migration of polyether to the surface. The protein adhesion force and quality were significantly reduced according to AFM-based colloidal probe technique and Quartz Crystal Microbalance with Dissipation, respectively. The coating exhibited antibacterial activity against Pseudoalteromonas xiamenensis (84.0%), Escherichia coli (69.2%) and Staphylococcus aureus (63.0%), respectively. 63.1% Halamphora. sp and 75.8% Nitzschia closterium f. had been inhibited, while the coatings possessed outstanding fouling release property with above 76.1% diatom detached after water exposure, proving that the amphiphilic parts weakened the adhesion of fouling. The mussel settlement assay confirmed that less adhesive plaques existed over the amphiphilic coatings. In addition, the expression for mussel adhesion proteins (mfp-5 and mfp-6) were significantly increased, demonstrating that amphiphilic polymers interfered with the adhesion response of the mussels. The effect on the interfacial behavior between fouling and coating is explored, providing a meaningful issue for the development of environmentally friendly antifouling coatings. [ABSTRACT FROM AUTHOR]

[Display omitted] • A molecular dynamics (MD) model for vibration-assisted grinding (VAG) with various vibration directions polycrystalline iron is established. • The MD model considers randomly distributed abrasive particles and initial rough surface. • VAG reduces average grinding force but increases instantaneous grinding force. • Lattice rotation and dislocation mediation are the mechanisms of plastic deformation of polycrystalline iron under VAG. • Radial vibration mainly improves surface microstructure, and axial vibration contributes to reducing surface roughness. Ultrasonic vibration-assisted grinding (UVAG) has attracted plenty of attention to significantly improve surface integrity. However, existing research has not systematically investigated the effect of vibration directions during UVAG at atomic and nanoscales, limiting our understanding of the plastic deformation mechanisms and microstructural evolution of ultra-precision machining. To address this issue, we proposed an MD model for multi-abrasive UVAG of polycrystalline iron considering various vibration directions. We comprehensively analyzed atomic flow fields, surface atom distributions, temperature fields, grinding forces, stress distributions, crystal orientations, and dislocation distributions. The simulation results demonstrate that UVAG effectively reduces grinding force and results in instantaneous grinding forces greater than conventional grinding (CG), and the instantaneous load impact phenomenon of radial vibration is more obvious. In surface morphology, axial vibration contributes to reducing surface roughness, while radial vibration is detrimental to surface smoothness. Microstructural evolution is mainly induced by stress. The primary plastic deformation mechanisms in UVAG of polycrystalline iron involve lattice rotation and dislocation mediation. Compared to axial vibration-assisted grinding (AVAG), radial vibration-assisted grinding (RVAG) and elliptical vibration-assisted grinding (EVAG) exhibit finer grain refinement, with RVAG leading to the highest dislocation density. [ABSTRACT FROM AUTHOR]

Through molecular dynamic simulations, the mechanism of CO 2 extracting hydrocarbon in rough surface was investigated. In the present study, the entrance effect of CO 2 molecules and the destruction of the miscible zone were considered as the critical factors in the extraction process. Subsequently, seven assistants were added to explore the main factors of the stability of miscible zone. The parameters of viscosity and solubility were chosen to characterize the properties of displacement agents and the dissolving capacity of CO 2 was proved to be the key to improving tight oil recovery in nanopores. In addition, when the roughness of the surface was adjusted from 2.2 to 3.9, the effects of the injection pressure on residual oil were different, laying emphasis on the significance of reservoir structure for CO 2 to enhance oil recovery. Moreover, our work also provided a molecular-level understanding of the CO 2 extraction of hydrocarbon in rough surface, and the results had some promise for the enhancement of oil recovery in CO 2 displacing engineering. Unlabelled Image • Dynamic miscibility with different CO 2 injection pressure was studied. • Continuous extraction was beneficial from the solute gradient. • Dissolving capacity of CO 2 was the key to EOR in tight oil reservoirs. • Extraction efficiency fluctuates with the roughness. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces that are durable and can be easily manufactured are of high interest for many industrial applications. Measuring and understanding roughness in the context of superhydrophobicity is the first step in creation of a surface that does not require activation to be hydrophobic. In this study, the as sprayed surface of different cermet (WC-10Co4Cr and Cr 3 C 2 -25Ni20Cr) coatings produced by High Velocity Air Fuel (HVAF) spraying – have been investigated to assess their wetting ability. In order to address the challenges raised by the specific roughness profile of thermal spray surfaces, two routes have been adapted and used for surface characteristics analysis i.e. statistical and fractal. Results show that both methods have a strong correlation to wettability. Roughness parameters S dq and S dr show good correlation with advancing contact angle. Hausdorff Dimension of a sub-micrometer profile shows good relation with the contact angle and provides information for state of the droplet. To determine how to increase the contact angle of the coating surface, coating parameters such as CGS Density have been correlated with Hausdorff Dimension. Both methods provide good understanding in terms of wettability of rough cermet surfaces. Unlabelled Image • High performance cermet coatings produced by High Velocity Air Fuel Spraying. • Hydrophobic properties of the coatings without surface activation • Roughness – wettability correlations by statistical analysis and fractal analysis • Wetting characteristics predictability [ABSTRACT FROM AUTHOR]

Owing to the layer-by-layer deposition characteristic of fused deposition modeling (FDM) process, parts produced via FDM have typical low surface quality and do not satisfy the requirements for end-use applications. Therefore, it is necessary to improve the surface quality of parts produced via FDM. In this study, laser polishing technology was employed to enhance the surface quality of aluminum fiber/polylactide acid (Al/PLA) composite parts produced via FDM. The surface roughness, surface morphology, dynamic mechanical properties, and tensile properties were investigated. With optimal polishing parameters, the laser polishing process removed the defects formed during the FDM process. The surface roughness was reduced from the initial value of 5.64 μm to 0.32 μm (Ra). The dynamic mechanical analysis (DMA) results showed that there was a remarkable improvement in the storage modulus (E ′), loss modulus (E "), and glass transition temperature of Al/PLA composite specimens after laser polishing. The re-melted and polished surface of the specimens also led to improvement in the tensile strength and Young's modulus. Lastly, the fracture morphologies were observed, and the possible strengthening mechanism was also discussed. These results indicate that laser polishing can be an efficient method for the surface polishing of FDM-printed parts. Unlabelled Image • Laser polished additive manufactured Al/PLA has higher surface quality and many defects are removed. • A maximum reduction in Al/PLA surface roughness of over 93% is achieved at optimized polishing settings. • Laser polishing effectively improves the dynamic mechanical properties and tensile properties of the FMD Al/PLA. • The strengthening mechanism induced by laser polishing is analyzed. [ABSTRACT FROM AUTHOR]

In the present work surface roughness of copper samples after mechanical surface preparation processes (polishing, grinding, sand-blasting) and after exposure in non-oxidizing (high purity argon) and oxidizing (air) conditions at 700 and 750 °C have been evaluated by contact profilometer and by fractal analysis. Quantitative description of surfaces that are hidden from the sight of conventional methods is possible by fractal analysis, e.g. in the present work, the roughness of Cu 2 O/Cu boundary has been evaluated under oxide layer. It has been pointed out, that in both oxidizing and non-oxidizing conditions initial surface roughness of copper is affected by annealing at high temperature: at 700 °C surface roughness of polished and ground samples increased but at 750 °C decreased in comparison to surface roughness prior to heat treatment. For sand-blasted samples in both oxidizing and non-oxidizing conditions the lowest values of surface roughness parameters were obtained at 750 °C. It is then concluded that two phenomena are responsible for such effect: chemical reaction between copper and oxygen and surface diffusion of copper due to high temperature of annealing. Unlabelled Image • Surface of copper samples had been polished, ground and sand-blasted. • Surface roughness had been evaluated by contact profilometer and fractal analysis. • There are differences in roughness after annealing in oxidizing and non-oxidizing conditions at different temperatures. • Changes in roughness are caused by chemical reaction between Cu and O and surface diffusion of Cu at high temperature. [ABSTRACT FROM AUTHOR]

The surface roughness of picosecond laser micromachined sidewalls in silicon is investigated theoretically and experimentally by varying the laser fluence, the focal spot size and the crater overlap. It is shown that the precise spot positioning and the repeated ablation induce a periodic structuring of the sidewall surface. The roughness measured by confocal microscopy along the laser scanning direction (R a X), can be decreased by increasing the crater overlap and the focal spot size. This behavior, confirmed using two different lasers, can be explained by a simple geometrical model. However, above an optimal crater overlap of approximately 80%, the surface roughness increases again. The sources of this limitation are discussed. The roughness measured along the beam propagation direction (R a Y) is minimal around a crater overlap of 80% as well. Varying the spot size does not significantly change R a Y but impacts on the curvature of the sidewall. Moreover, it is shown that once the sidewall is fully formed, its surface roughness is barely dependent on the number of laser scanning passes. Unlabelled Image • Sidewall roughness of laser engraved cavities depends highly on the crater overlap. • Laser engraving induces a periodic structuring of the sidewall surface. • The roughness can be tuned by varying the crater overlap and size. • This behavior is well explained by a simple geometrical model. • Several factors prevent the formation of super smooth (nm scale) sidewall surface. [ABSTRACT FROM AUTHOR]

Shot peening is a well-established surface treatment commonly used to improve mechanical properties of material's surfaces. Studies have shown notable enhancement of fatigue strength, wear, scratch and corrosion resistance and fretting properties as a result of an intensive shot peening treatment, the so-called severe shot peening. Nevertheless, this process has some drawbacks including quite high surface roughness and possible embedment of shot residuals at the treated surface, which can have adverse effects depending on the final application. In this paper, electropolishing has been evaluated as a cleaning post-treatment for shot peened surfaces of 316L stainless steel. For this purpose, electropolishing voltage has been varied with the aim of obtaining clean and smoother surfaces without sacrificing the mechanical improvements produced by shot peening. The treated surfaces have been characterized considering surface roughness, morphology, wettability, residual stresses and microhardness evolution after various shot peening treatments combined with electropolishing using different parameter set-ups to identify the most promising combinations. Unlabelled Image • Peened surfaces are rough with embedded residual shots, adverse for some applications. • Electropolishing selectively produces bright, clean and smooth surfaces. • An effective electropolishing cleaning treatment was suggested for peened surfaces. • Mechanical improvement produced by shot peening were maintained after electropolishing. [ABSTRACT FROM AUTHOR]

The oxygen vacancy properties of densified titanium oxide (TiO 2) nanocrystals (NCs) with different surface ligand states were evaluated. Fluorous ligand modification resulting in the high densification of NCs and the effect of residual ligands on the surface of the NCs using ultraviolet (UV)-exposure treatment were investigated. After synthesizing the TiO 2 NCs at 80 °C, their modification proceeded using 2,2,2-trifluoroacetic acid as the fluorous ligand. NC thin films were formed using spin-casting, after which the UV-exposure treatment was performed. According to the analytical results of crystalline size, surface, optical properties, and surface ligand states of the TiO 2 NCs, the ligands on the NCs were decomposed by the UV-exposure treatment under various atmospheres and the flatness of the NC thin films was found to be controlled by the fluorous ligand modification. Thus, the recombination effect of the oxygen vacancies could be controlled by the fluorous ligand modification and UV-exposure treatment. Unlabelled Image • TiO 2 nanocrystals were synthesized at a low temperature. • The fluorination of the nanocrystals improved the surface roughness. • UV irradiation controlled the thickness and flatness of the nanocrystal thin films. • Fluorination and UV irradiation induced densification of the nanocrystal thin films. • Fluorination and UV irradiation reduced the surface oxygen vacancies on the nanocrystal thin films. [ABSTRACT FROM AUTHOR]

Shot peening is a typical surface strengthening process that is widely applied in engineering practice for it can introduce finer grains in the near-surface layer and generate a compressive residual stress (CRS) layer. The finite element method, together with a Python subscript, is applied to create a multiple-shot model to estimate the evolution of the shot peening coverage. The influences of coverage on residual stress, plastic strain and surface topography are discussed. The predicted results reveal that as the shot peening coverage increases from 100% to 400% under the given processing condition, the maximum CRS and the plastic strain will increase gradually. But there is no evident alteration on the width of CRS layer and plastic strain layer. The variations of each roughness parameter with coverage are different. • A finite element multi-shot model with Python subscript is developed to investigate the evolution of shot peening coverage. • Influence of coverage on the residual stress distribution, plastic strain and surface topography are discussed. [ABSTRACT FROM AUTHOR]

In this work laser surface texturing of Ti-11.5Mo-6Zr-4.5Sn β-Ti alloy is investigated with different laser wavelengths and pulse durations. For benchmark purposes, three different industrial solid-state laser sources providing four different wavelength/pulse duration combinations were used. Within the experimented range pulse duration could be varied at 2.5 ps, 6 ns and 250 ns at 1064 nm, while 5 ns pulse duration was tested at 355 nm. The comparative analyses were carried within the process parameter ranges available to the laser sources in order to assess the quality and productivity aspects. In particular, surface roughness, wettability, and chemical composition were quantified as well as assessing the distinct surface morphologies obtained with different configurations. Process productivity was analysed for each configuration in terms of machining rate. The results exhibit a large variety of possible surface textures available to biomedical implant designers with nanometric to micrometric features and tailorable chemical and wetting properties. Moreover, the results help in understanding how the light/matter interaction changes between different pulse durations and wavelengths. • LST of β III Ti-alloy studied with four different laser configurations • Ps- to ns-pulsed lasers with NIR to UV wavelengths were tested. • Formation of LIPSS, ordered, and chaotic surface structures were demonstrated. • Link between surface roughness, chemistry, and wettability established • Allocation of texture types to an orthopaedic implant was carried out. [ABSTRACT FROM AUTHOR]

In this paper, Laser shock wave planishing processing (LSWP) is performed on the CNC milling surface of LY2 aluminum alloy. The influence of contact foil roughness on the surface roughness of the workpiece is analyzed. The results show that in a single LSWP, the coarser the contact foil, the higher the removal of the milling marks. The contact foil is not smoother and more effective. For surfaces with different roughness, there is a corresponding contact foil with appropriate roughness, which can minimize the roughness of the workpiece. By selecting a contact foil of suitable roughness, LSWP can greatly reduce the NC machining surface with high initial roughness and simplify the CNC milling process. The surface roughness of CNC milled surface can be reduced from 3.12 μm to 0.977 μm after one LSWP impact. In multiple LSWPs, the surface roughness of the contact foil in the previous LSWP treatment will seriously affect the effect of the latter LSWP, so the choice of film contact roughness is particularly important. The surface roughness of CNC milled surface can be reduced from 3.07 μm to 0.562 μm after two LSWP impacts. • LSWP can effectively eliminate the milling tool marks. • Surface roughness of milling surface is greatly reduced when treated by LSWP. • A contact foil with suitable roughness must be chosen to minimize roughness. • By choosing appropriate contact foil, multiple LSWP can reduce surface roughness effectively. [ABSTRACT FROM AUTHOR]

Paper-based platforms for biological studies have received significant attention given that cellulose is ubiquitous, biocompatible, and can be readily organized into tunable fibrous structures. In the latter form, effect of complexity in surface morphologies (roughness, porosity and fiber organization) on cell-substrate interaction has not been thoroughly explored. We infer that altering the properties of a fibrous material should lead to significant changes in cellular microenvironment and direct the deposition of structurally analogous extracellular matrix (fiber-fiber templating) like collagen. Here, we elucidate the effect of varying paper roughness and surface chemistry on NIH/3T3 fibroblasts via organization of excreted collagen. Collagen intensity was found to increase linearly with paper porosity, indicating a 3D culture platform. The intensity, however, decays over time due to biodegradation of the substrate. Stability can be improved by introducing fluorinated alkyl silanes to yield hydrophobic paper. This process concomitantly transforms the substrate to a 2D-like scaffold where collagen is predominantly assembled on the surface, thus changing the cellular microenvironment. Altering surface energy also led to fluctuations in collagen intensity and organization over time for smooth (calendered) paper substrates. We infer that the increased roughness improves collagen adsorption through capillary driven petal effect. In general, the influence of the substrate simultaneously affects its ability to host collagen and guide orientation. These findings offer insights into the effects of secondary structures and chemistry of fibrous polymeric materials on cell culture, which we propose as vital parameters when using paper-based platforms. Unlabelled Image • Collagen secreted from NIH/3T3 fibroblast cells increases linearly with paper porosity. • Paper transitions from 3D to 2D cell culture scaffold when rendered hydrophobic. • Hydrophobic paper relies on capillary driven petal effect for collagen adsorption. [ABSTRACT FROM AUTHOR]

Novel polystyrene (PS)/CeO 2 -TiO 2 multicomponent core/shell abrasives were developed and exploited for high-efficiency and high-quality photocatalytic-assisted chemical mechanical polishing (PCMP) of the reaction-bonded silicon carbide (RB-SiC). Firstly, we proposed a modified process to synthesize the novel core/shell abrasives, which possessed a particular yielding effect and an enhanced photocatalytic activity. The as-synthesized abrasives were then characterized by FESEM and XRD, which showed that the CeO 2 -TiO 2 shells were coated on the PS cores successfully, with the average particle size of ca. 200 nm (shell: 20 nm, core: 160 nm). PCMP experiments of RB-SiC were then conduct by exploiting deionized water contained 2.0 wt% CeO 2 , CeO 2 -TiO 2 , PS/CeO 2 , and PS/CeO 2 -TiO 2 abrasives, respectively. Surface roughness values of RB-SiC before and after PCMP were measured by AFM, which showed that the core/shell based abrasives had the potential to obtain a better polishing quality compared with conventional abrasives. Material removal rates (MRRs) with CeO 2 -TiO 2 based abrasives were higher than those of CeO 2 based abrasives under ultraviolet (UV) irradiation. The best polishing performance (R a : 0.497 nm, MRR: 1.223 μm/h) was obtained with PS/CeO 2 -TiO 2 abrasives under UV irradiation. Detailed action mechanisms for obtaining the better polishing quality and higher MRR were explained by the particular yielding effect of core/shell based abrasives and the enhanced photocatalytic activity of CeO 2 -TiO 2 based abrasives, respectively. • Novel PS/CeO 2 -TiO 2 core-shell abrasives are synthesized via a modified process. • PS/CeO 2 -TiO 2 abrasives can be applied to chemical mechanical polishing of RB-SiC. • PS/CeO 2 -TiO 2 abrasives possess a particular yield effect when polishing. • Photocatalytic activity of the PS/CeO 2 -TiO 2 abrasives is much enhanced. • Polishing quality and efficiency are improved with the PS/CeO 2 -TiO 2 abrasives. [ABSTRACT FROM AUTHOR]

The presence of surface energy has an important effect on the physical and mechanical performance of nanoscale structures and materials. Determining the value of surface energy density has raised great concern in surface science. Especially, how to estimate the surface energy density of curved and even stochastically rough surfaces remains unsolved. The present paper is aimed to investigate the surface energy density of rough metal surfaces by atomistic calculations. The surface energy densities of periodic sinusoidal surfaces and stochastically rough surfaces are calculated. Simulation results suggest an analytical model to determine the surface energy density of rough surfaces by the surface geometric parameters and the surface energy density of planar surface. • Atomic simulation model for calculating the surface energy density of rough surface was established. • The surface energy densities of stochastically rough surfaces with different roughness were calculated. • Proposed a simple theoretical model between surface energy density and roughness [ABSTRACT FROM AUTHOR]

Superhydrophobic surface has aroused wide concern over the years due to its extensive application prospect. However, a simple, cost-effective and environmental friendly preparation method is still lacking. Here, we present an effective approach to prepare a superhydrophobic surface for long-term metal corrosion protection. Positively charged SiO 2 composite nanoparticles were successfully prepared by a simple and multiple ultrafiltration method firstly, after that the particles were sol-gel electrodeposited on steel to build micro-nano roughness surface, and then the surface was modified by cost-effective and fluorine-free chemical stearic acid with low energy surface. The results of wettability experiment show a strong repulsive force between the modified surfaces and water droplets, with static contact angles over 158°. The corrosion resistance and corrosion current density of the Al 2 O 3 @KH560@SiO 2 composite film assessed by the electrochemical impedance spectroscopy (EIS) and the polarization and neutral salt spray test indicate that the corrosion rate of the metal is reduced and the corrosion performance of the matrix is improved at the same time. Unlabelled Image • A fluorine-free and environment-friendly superhydrophobic surface was prepared. • The preparation method is simple in operation and suitable for all kinds of conductive substrates. • The resistance and anti-corrosion property of metals have been improved greatly by superhydrophobic surface. • The superhydrophobic film has long-term protection to the metal substrate. [ABSTRACT FROM AUTHOR]

Highly robust and smooth silver nanowire flexible transparent electrodes (AgNW FTEs) with UV-curable polymeric resin as an overcoating layer were fabricated via successive Mayer rod method followed by UV light curing process, and the mechanical and chemical stabilities, electromagnetic interference shielding effectiveness (EMI SE) and film-heating property of the resultant overcoated AgNW FTEs were investigated. The results show that the fabricated AgNW FTEs with overcoating layer has a smooth surface with a root-mean-square (RMS) surface roughness value of 1.07 nm, and the overcoating layer generates a slight decrease of sheet resistance of AgNW FTEs from 8.1 to 7.9 Ω/sq, and the transmittance of 91.3% at 550 nm maintains basically. The overcoated AgNW FTE shows high mechanical and chemical stabilities, and the opto-electrical properties do not spoil after 10 times of scratching or 30 times of wiping or dipping into Na 2 S solution for 600 s. The overcoated AgNW FTEs possesses an EMI SE of 28.1 dB, and a heating temperature of 93.5 °C in 30 s on 12 V even after inputting and turning off the voltage for 30 times with a duration of 4 h. It indicates that the overcoated AgNW FTEs has great potential application in the fields of EMI shielding and film heater. • The overcoating layer forms a smooth surface with the RMS roughness value decreases to only 1.07 nm. • The overcoating layer enhances the stability showing resistance to scratching, wiping or dipping into 5 wt.% Na 2 S solution. • The overcoated AgNW FTE shows an EMI SE as high as 31.50 dB and the film heater reaches 93.5 °C in 30 s on 12 V. [ABSTRACT FROM AUTHOR]

Multilayer profiles are studied using the MRI model with extension to preferential sputtering. The results show a clear distinction with respect to the main contributions to the depth resolution, namely surface and interface roughness, and atomic mixing. For dominating roughness, the effect of preferential sputtering is more pronounced for the residual surface composition profile (detected by XPS and AES), but it is zero for the sputtered matter composition profile (detected by SIMS). Dominating mixing results in a strong effect of preferential sputtering on the shape of the profile. While in that case its effect on the XPS or AES depth profile is relatively moderate, its effect on the SIMS depth profile is surprisingly strong and appears to be in contradiction to textbook statements. Interface width, location and layer thickness are always affected by preferential sputtering in XPS and AES depth profiles, but SIMS depth profiles are only affected if the contribution of atomic mixing to depth resolution cannot be ignored. In conclusion, a new definition of multilayer resolution is proposed which is based on the normalized amplitude of the wave-like profiles. The successful application of MRI model extended for preferential sputtering is given for fitting an experimental AES depth profile of an Ag/Ni multilayer. • Quantitative prediction of preferential sputtering effect on multilayer profiles • 50% amplitude layer thickness depends on preferential sputtering rate ratio. • Behavior of XPS and SIMS depth profiles with preferential sputtering is different. • For dominating roughness, SIMS is independent of preferential sputtering. • For dominating atomic mixing, SIMS strongly depends on preferential sputtering. [ABSTRACT FROM AUTHOR]

In this work, the effect of increasing Si content in the absorber layers (CrAlSiN x /CrAlSiO y N x) of solar selective absorbers upon their selectivity and thermal stability are studied. The two optical stacks presented consist of four magnetron sputtered layers on stainless steel substrates. In both cases, tungsten is used as back-reflector, CrAlSi x N/CrAlSiO y N x as absorber layers with different Si/(Cr + Al + Si) atomic ratio (0.15 and 0.30, respectively) and finally the SiAlO x antireflection layer. The structures were theoretically designed by SCOUT software depended on experimental transmittance (T) and reflectance (R) of thin single layers deposited on glass substrates. It is observed that optical stack coatings with higher silicon content show better selectivity values, high solar absorptance, α = 95.9%, and low emissivity, ε = 9.7% (calculated for 400 °C), with higher thermal stability at 600 °C in vacuum, for 650 h. Additionally, with the annealing at 600 °C an increase of surface roughness was found, which was smaller for sample with higher Si content. Unlabelled Image • W/CrAlSiN x /CrAlSiO y N x /SiAlO x tandem for solar selective absorption. • Better performance was obtained with absorption layers with Si/(Cr + Al + Si) = 0.3 • Excellent thermal stability at 600 °C, in vacuum, and 450 °C, in air • High solar absorptance, α = 95.9%, and low emissivity, ε = 9.7% (for 400 °C) [ABSTRACT FROM AUTHOR]

Simultaneous existence of topographic and chemical cues on the polymeric surface was demonstrated to be a valid route to accelerate osteoblast differentiation. Herein, nanotopographical pattern and bioactive components were sequentially introduced onto the poly(l -lactic acid) (PLLA) surface via etching treatment followed by mussel-inspired polydopamine (PDA) coating. The PLLA nanolamellae were formed on nanotopographical surface with the roughness of 62.0 nm by extracting the amorphous phase of annealed PLLA. Subsequently, uniform PDA decoration was obtained on the etched surface without changing the surface roughness via dopamine self-polymerization. In vitro cell culture revealed that the combination of nanolamellae and PDA decoration showed more significant promotion of cell viability, alkaline phosphatase activity, osteopontin, and collagen type I expression than only using nanolamellae or PDA decoration. The enhanced osteoblast differentiation was mediated by the integrin β1 signaling pathway. Our proposed approach opens a simple, universal, and promising gateway to construct polymeric surface with comprehensive cues for enhancing osteogenic differentiation. Unlabelled Image • Physical and chemical cues were introduced onto the PLLA surface by combining etching treatment and PDA coating. • PLLA surface with nanotopographical and chemical cues exhibited superior ability to induce osteoblast differentiation. • The designed surface cues offer a promising way to enhance osteogenic capacity for polymeric implants. [ABSTRACT FROM AUTHOR]

This work investigated a two-step surface modification of polyamide meshes and nonwoven fabrics for oil/water separation and looked into the durability of such modified polyamide. The two-step modification included 1) pre-etching the polyamide surface using plasma treatment and 2) coating the pre-etched surface by eco-friendly polydopamine (PDA)/cellulose. The pre-etching increased the surface roughness, which further improved the underwater superoleophobicity of the coating. Therefore, the modified polyamide was able to separate various oil/water mixtures and showed a higher intrusion pressure than the original sample and the samples which were only etched or only coated. The grooves on the surface that resulted from the pre-etching prevented the coating from peeling off. In durability tests, after 6 repeated uses, the modified nonwoven sample lost its underwater oleophobicity due to severe oil fouling, coming to a complete failure in oil/water separation. After 19 cycles, the modified mesh was still able to separate a certain amount of oil/water but showed reduced intrusion pressure because of slight oil contamination. Filters with different structures, like meshes with one layer of pores and nonwoven fabrics with complex three dimensional pores, had different oil fouling levels that affected oil/water separation. The recoverability of filters from oil contamination should be considered for practical applications. Unlabelled Image • A two-step method combining pre-etching and coating is developed for oil removal. • PDA/cellulose coating is novel, eco-environmentally and effective for oil removal. • Pre-etching creates rugged surfaces that enhance wettability and reinforce coating. • Nonwoven fabrics are less durable than meshes due to their layers of complex pores. • Complex pores lead to difficult recovery from oil fouling and worse durability. [ABSTRACT FROM AUTHOR]