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A surface micro/nano structuring technique was demonstrated for colorizing metal surfaces with a picosecond laser. Sequential color change from black to pink was realized on copper surfaces by simply changing the ps laser scanning speeds. Systematic analyses on the spectral response and microstructure characteristics were reported. The spectrum shifting effect corresponding to color change was explained through the surface plasmon resonance mechanism. The current research shows that a high power and high repetition rate ps laser is capable of structuring metal surfaces with a speed up to several meters per second, presenting an efficient and affordable candidate for practical industrial applications. [ABSTRACT FROM AUTHOR]

Optical functional surfaces are key components of nearly every optical device and they have become a special focus in both academia and industry. The no contact, one step, direct, and maskless laser surface texturing technique is one of the most encouraging approaches for realizing the surface functions. We use a high power and high repetition rate ultrafast laser system to produce micro–nano structures on metal surfaces. We demonstrate that metal surface micro–nano structures and correspondingly their optical responses can be facilely tailored by simple controlling the ultrafast laser processing parameters. Nano particles of tens to hundreds nm, sub-micro particles of 0.5–1 μm, fine-micro particles of 1–10 μm, micro particles of 10–50 μm, and coarse-micro particles larger than 50 μm have been fabricated on Cu surfaces. And surface reflection of copper surfaces has been tuned from 10% to 90% in spectra level and from UV to MIR in spectrum range, with unique optical properties like visible selective reflection, linear changing reflection, band reflection, and broadband absorption being achieved. The formation processes of those particle structures as well as the underlying mechanisms for their optical responses are discussed. [ABSTRACT FROM AUTHOR]

Studies regarding the wettability transition of micro- and nano-structured metal surfaces over time are frequently reported, but there seems to be no generally accepted theory that explains this phenomenon. In this paper, we aim to clarify the mechanism underlying the transition of picosecond laser microstructured aluminum surfaces from a superhydrophilic nature to a superhydrophobic one under ambient conditions. The aluminum surface studied exhibited superhydrophilicity immediately after being irradiated by a picosecond laser. However, the contact angles on the surface increased over time, eventually becoming large enough to classify the surface as superhydrophobic. The storage conditions significantly affected this process. When the samples were stored in CO 2 , O 2 and N 2 atmospheres, the wettability transition was restrained. However, the transition was accelerated in atmosphere that was rich with organic compounds. Moreover, the superhydrophobic surface could recover their original superhydrophilicity by low temperature annealing. A detailed XPS analysis indicated that this wettability transition process was mainly caused by the adsorption of organic compounds from the surrounding atmosphere onto the oxide surface. [ABSTRACT FROM AUTHOR]

Abstract: WC/Ni coating was formed by laser cladding of a W/C/Ni powder blend. The formed WC crystals have rectangular or quadrangle cross-section shapes with size of 2–30μm. Step, twist and cross growth morphologies of WC formation were observed. The coating contains WC, CW3, WNi, FeW3C, Fe6W6C, W3O, W, C, and (Fe,Ni) phases. [Copyright &y& Elsevier]

Abstract: To reduce the mixed fuel induced excessive wear of the cast iron engine cylinder liners, research on laser alloying of NiCr alloy with powder feeding was performed to locally change both the composition and the microstructure of the liner. The research indicated that laser alloying of 75Ni25Cr on grey cast iron liner demonstrates sound alloying layers free of cracks and porosities. The microstructure of the alloyed layer is composed of pre-eutectic austenite and ledeburite. The alloying element Ni is mainly located in the austenite, while Cr is mainly in cementite. The average hardness is HV0.2500. The corrosion resistance of the alloyed layers in diluted H2SO4 solution and NaOH solution is dramatically improved compared to the grey cast iron. The relative wear resistance of the laser-alloyed 75Ni25Cr layer is 4.34 times of that of the grey cast iron. The improvements on the corrosion and wear resistance of the cast iron are attributed to the composition and microstructure change by laser alloying of 75Ni25Cr. Laser alloying can be a good solution to improve wear and corrosion resistance of the grey iron liners in mixed fuel environment. [Copyright &y& Elsevier]

Abstract: Laser deposition of Inconel 738 on directionally solidified (DS) Ni-based superalloy demonstrates a strong susceptibility to cracking. Cracks originate from the liquation of low melting point eutectic on the DS grain boundary. Five boundary liquation and interface cracking styles were identified. Sound Inconel 738 deposition layers were achieved free of cracks. [Copyright &y& Elsevier]

Laser direct manufacturing (LDM) has been intensively developed in recent years to directly and flexibly manufacture metallic components with full metal density, functions and properties, especially for some specific materials or geometry. This paper presents a project work on laser direct manufacturing a novel designed collimation component for an out-space hard X-ray modulation telescope. The research work contained the characteristics of overlap multi-pass laser cladding of tungsten or tungsten nickel alloys, microstructure analyses, technique stability of laser direct manufacturing, and the final direct manufacturing of tungsten nickel collimation component. The results proved that laser direct manufacturing could be well used to manufacture specific material and geometry component of good quality, which are very difficult or even impossible by conventional manufacturing methods. [Copyright &y& Elsevier]

A composite coating with TiC particles of various shapes and sizes embedded in nickel based alloy has been in situ synthesized by laser melting a precursor mixture of nickel based alloy powder, graphite and titanium powders. The experiment result showed that the coating epitaxially grew from the substrate with excellent bonding between the coating and the carbon steel substrate. The coating is uniform, continuous and free of pores and cracks, and about 0.6 mm thick. The microstructure of the coating is mainly composed of γ-Ni dendrite, a small amount of interdendritic (γ-Ni+M23C6) eutectic, and dispersed TiC particles. The volume fraction of TiC particles and the microhardness gradually increased from the bottom to the top of the coating layer. [Copyright &y& Elsevier]

The microstructural evolution in high power CO2 laser cladding of steel with Stellite 6+WC powder mixture was investigated, among which the WC vol.% was, respectively, 0, 9, 18, 27, 36, 45, 54, 72 and 100% by dual powder feeding Stellite 6 and WC powders with different feeding rates. Two significantly different solidification characteristics were found in the microstructural evolution in laser clads of Stellite 6+WC. The first one was characterized by the dendrites and interdendritic eutectics from 0 to 36% WC, in which the added WC was completely melted into the melt pool and the re-solidified structure contained α-Co,σ-CoCr and various carbides such as M7C3. The second one was characterized by various faceted dendrites in block, flower, butterfly, star shapes and the matrix from 45 to 100% WC, in which most of the WC was melted, the microstructure contained re-solidified WC, Co and various Co–W–C/Fe–W–C complex carbides. Maximum 26 and 64 wt.% W were, respectively, dissolved into the matrix and the faceted dendrites. When laser cladding WC powder with severe dilution from the substrate, a microstructure with different composition appeared within the faceted dendrites with interior approximately 90 wt.% of W and exterior approximately 70 wt.% of W. Such a structure was probably the frozen result of the peritectic reaction during laser cladding rapid solidification. [Copyright &y& Elsevier]

Background: Serum amyloid A has been widely reported as a useful biochemical marker in the diagnoses of acute appendicitis. The aim of this study was to appraise the diagnostic accuracy of serum amyloid A in the diagnosis of acute appendicitis. Methods: A systematic search of several databases was conducted. The search time was from the beginning of the databases creation to March 1, 2021, and the languages were restricted to English and Chinese. Clinical studies using serum amyloid A for the diagnosis of acute appendicitis were included. The overall sensitivity and specificity were calculated by using a bivariable mixed effects model. Heterogeneity was tested using I2 statistics. This study has been registered on the International Prospective Register of Systematic Reviews (PROSPERO; no. CRD42021241343). Results: Five studies comprising 668 participants were eligible for inclusion. The overall sensitivity and specificity of serum amyloid A in diagnosing acute appendicitis were 0.87 (95% confidence interval [CI], 0.79-0.92) and 0.74 (95% CI, 0.59-0.85), respectively. The positive and negative likelihood were 3.3 (95% CI, 2.1-5.4) and 0.18 (95% CI, 0.11-0.28), respectively. The area under the summary receiver operating characteristic curves was 0.89 (95% CI, 0.86-0.91). The heterogeneity was significant (I2 = 82%; 95% CI [63%-100%]). Conclusions: Serum amyloid A has good diagnostic accuracy for acute appendicitis. It is expected that serum amyloid A could be helpful in the early clinical diagnosis of acute appendicitis. [ABSTRACT FROM AUTHOR]

Highlights: [•] Superhydrophobic and colorful copper surfaces were fabricated by picosecond laser nanostructuring. [•] The effects of laser processing parameters on the LIPSS formation were discussed. [•] The laser nanostructured surfaces exhibited different adhesive forces to water. [•] Some of the laser nanostructured surfaces presented a superhydrophobic behavior. [ABSTRACT FROM AUTHOR]

Abstract: Nano-particulate reinforced metal matrix composites (nPRMMCs) exhibit excellent comprehensive properties unmatched by conventional micro-particulate reinforced metal matrix composites (μPRMMCs). However, current techniques for fabricating nPRMMCs usually use nano-powders as raw materials, which are not preferred due to their agglomeration trend and harmful size. In this paper, we developed a technique to fabricate nano-TiCp reinforced Inconel 625 composite coatings by laser cladding of an Inconel 625+5wt.% TiC powder mixture, particle size of the raw powders both in micrometer range. By controlling the specific energy input, the micro-TiCp partially dissolved into nanometer scale. The influence of specific energy input on particle size, morphology and the microstructure, phase constitution and mechanical properties of the composite coatings were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and nano-indentation test. Nano-TiCp reinforced Inconel 625 composite coatings were achieved at the specific energy input of 25.3kJ/g. The hardness and modulus of the nPRMMCs are 3.36GPa and 190.91GPa, increased by 10.33% and 12.39% respectively compared to laser cladded Inconel 625 substrate. The nPRMMCs show potential in applications such as the fabrication of turbine blades and engine components with improved performance. [Copyright &y& Elsevier]

Abstract: In this paper, the nanojoining method of graphene sheets (GSs) by ion beam irradiation is proposed and the joining process is researched by classical molecular dynamics simulations. We demonstrate that the carbon ion beam irradiation should result in the joining of overlapped GSs. And it is found that these joining processes are attributed to two different mechanisms. In addition, the influences of the ion parameters on the properties of the graphene joints are also investigated and the optimum ion parameters are derived for industrial applications. [Copyright &y& Elsevier]

Abstract: We report the investigations on structural modifications in monolayer graphene induced by low-power-density CO2 laser irradiation (2–60W/cm2). Observed modifications in graphene include the disassembly of crystalline graphene into nanocrystalline structure and the generation of amorphous carbon. It was found that thermal effect played an important role during laser irradiation. By adjusting laser power density, irradiation time and temperature, the structure of graphene can be modified accordingly in a controlled manner. Our approach may enable high-efficiency and economical modification of large-area graphene, which relies on large-area irradiation using low-power-density laser. [Copyright &y& Elsevier]

Abstract: A novel technique, named nano-particle surface injection via laser shock peening-NPSI/LSP, for surface modification of light alloys is reported. The WC nano-particles were implanted into a 5A06 aluminum alloy surface under a very high pressure (up to Giga or even tens of Giga Pascal), produced by a Q-switched pulsed Nd:Glass laser system. The results confirmed that the surface performance of the 5A06 aluminum alloy have been dramatically improved by the NPSI/LSP process based on an integrated strengthening mechanism of laser shock peening, nano-particles and nano-particle intensified shock peening. [Copyright &y& Elsevier]

Abstract: Hydrophobic Cu surfaces with tunable regular microstructure and random nanostructures were fabricated by nanosecond pulsed laser texturing and chemical etching. The regular micro-scale roughness can be tuned from 5μm to 30μm Rz by nanosecond laser texturing while the ligament width and spacing of the random nano porosity about 10–50nm can be realized by selective chemical etching. Wettability tests demonstrate that the Cu surface with this micro/nanostructural hierarchy, analogous to that of lotus leaves found in nature, is superhydrophobic with a water contact angle around 153°. The random nanostructure by selective etching plays an important role for hydrophobicity in addition to the regular microstructure by nanosecond laser texturing. [Copyright &y& Elsevier]

Abstract: Fabrication of nanoporous Cu–Mn alloy coatings was investigated by a two-step process involving high power laser cladding of a homogeneous Cu40Mn60 alloy coatings followed by selectively electrochemical de-alloying. Auger mapping results indicate that nanoporous manganese was obtained by selective electrochemical etching of the less active Cu component owing to the passivation of the more active manganese in potassium nitrate solution. The surface morphology of the porous Mn was a ribbon-like structure, different from interconnected bicontinuous nanopores that are usually obtained by de-alloying. The influence of de-alloying time, electric potential and temperature on the formation of nanoprosity is systematically investigated. Nanopore sizes can be tailored to be less than 100nm. Under optimal etching conditions the nanopore size was below 25nm. The surface area of the nanoporous manganese layer was enhanced by up to 990 times compared with that of a polished sample. [ABSTRACT FROM AUTHOR]

It is known that the press formability and the elongation of laser textured sheet are improved, and the service life of textured roll is longer than that of the un-textured roll due to hardening of the treated surface. One of the goals to develop high repetitive rate YAG laser-induced discharge texturing (LIDT) is to get deeper hardening zone. By observing and measuring cross-section of LIDT spots in different discharge conditions, it is found that the single-crater, which is formed by the discharge conditions of anode, which is covered by an oil film and with rectangular current waveform, has the most depth of heat affected zone (HAZ) comparing with other crater shapes when discharge energy is the same. The depth of HAZ is mainly depends on pulse duration when the discharge spot is single-crater. The results are analyzed. [ABSTRACT FROM AUTHOR]

Abstract: A PRC-3 kW continuous wave CO2 laser was used to clad a MoS2/TiC/Ni coatings on the surface of a 1045 low carbon steel substrate. The microstructure and phase composition of the composite coating were studied. The typical microstructure of the composite coating is composed of multi-sulfide phases including binary element sulfides, ternary element sulfides, Ni, TiC and Mo2C. Wear tests were carried out using a FALEX-6 type pin-on-disc machine. The results showed that the MoS2/Ni coating (as a contrasted sample) exhibited the lowest friction coefficient and the largest weight loss in comparison to other investigated specimens. The friction coefficient of the MoS2/TiC/Ni coating is lower than that of quenched 45 steel and weight loss is only one-sixth of that of 45 steel. The worn surface of MoS2/TiC/Ni laser cladding coating is so clean and smooth (no noticeable groove and scratches visible) that the microstructure of coating is identified after dry wear test of 40 min. [Copyright &y& Elsevier]

Detailed experiments have been conducted to produce a nickel-based alloy composite coating reinforced with TiC particles on medium carbon steel substrate by powder feeding laser cladding using a coaxial nozzle. The chemical compositions, microstructures and surface morphology of the coatings were analyzed using scanning electron microscopy (SEM), energy disperse X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Composite coatings with TiC particles of various shapes and sizes embedded in nickel-based alloy were synthesized in-situ during laser processing. An excellent bonding between the coating and the carbon steel substrate was obtainable. The coatings were uniform, continuous and free from cracks. The microstructure of the coating was mainly composed of γ-Ni dendrites, a small amount of CrB, Ni3B, M23C6 and dispersed TiC particles. The maximum microhardness of the coating was about HV0.21200. [Copyright &y& Elsevier]

High-throughput experiments involving isolated droplets based on patterned superwettable surfaces are important for various applications related to biology, chemistry, and medicine, and they have attracted a large amount of interest. This paper provides a directional anchoring liquid-infused superamphiphobic surface (DAS), via combining concepts based on the droplet-anchoring behavior of beetle backs with patterned wettability, the directional adhesion of butterfly wings, and the slippery liquid-infused surfaces (SLISs) of pitcher plants. Regularly arranged ">"-shaped SLIS patterns were created on a superamphiphobic (SAM) background through ultrafast-laser-based technology. Improved directional anchoring abilities with a sliding angle difference of 77° were achieved; this is the largest sliding angle difference in a one-dimensional direction achieved using an artificial surface, to the best of the authors' knowledge. Thanks to the directional anchoring abilities, the DAS coupled droplet 'anchoring' and 'releasing' abilities. Furthermore, a high-throughput droplet manipulation device was designed, on which a micro-droplet array with a large number of droplets can be 'captured', 'transferred', or 'released' in a single step. With the addition of lubricant, the DAS can work continuously for even more than 30 cycles without cross-contamination between different droplets. The DAS also shows good stability under an ambient atmosphere and can maintain its functionality when manipulating corrosive droplets. The DAS and corresponding high-throughput droplet manipulation method are excellent candidates for practical applications. [ABSTRACT FROM AUTHOR]

• A hybrid fabrication method combining ultrafast lasers ablations and rotational homogenization process was developed to construct uniform PDMS micro-nanostructures systematically. • The novel rotational homogenization process utilized centrifugal forces to confront surface tensions, achieving uniform distribution of PDMS on various microstructures. • Multiple tests were applied on the superhydrophobic surfaces, showing their comprehensive durability against mechanical and chemical damages, especially their recovery in freezing-melting cycles and resistance to supercooled droplet intrusion in −20 °C environment. Superhydrophobic surface is one of the most promising materials for the prevention and elimination of ice in daily lives but its durability remains a tremendous problem. Inevitable deterioration on the low-free-energy coating caused by harsh environment restrains their potential applications. Icephobic polymers are more durable than mostly used fluorosilanes for their higher thickness and cohesive strength but difficult to be uniformly modified on rugged micro-nanostructures. In this study, a nanostructured tungsten carbide doped PDMS layer was uniformly covered on aluminum microcones via a hybrid fabrication process combining nanosecond and femtosecond laser ablations and a rotational homogenization process. The prepared superhydrophobic surfaces exhibited excellent water repellency and anti-icing properties in icing-deicing cycles, water flow impacting and freezing-melting cycles. Multiple mechanical/chemical damage tests were performed to test their durability comprehensively. In mechanical tests, the surfaces could withstand linear abrasion length of 240 cm under 5.2 kPa pressure, impacting sand amount of at least 80 g or tape peeling for at least 200 cycles. The chemical durability was elucidated in −40 to 200 °C cycles, 2-day ultraviolet exposure and immersion in different liquids. The proposed hybrid method to form homogenous, ductile and durable superhydrophobic coatings could yield a prospective candidate for applications in anti-fouling and anti-icing. [ABSTRACT FROM AUTHOR]

Intelligent and adjustable building envelopes have the advantages of energy saving and comfort compared to traditional building envelopes and are an important direction for future development in the field of building engineering. However, complex regulation principle and redundant control methods limit their practical applications and large-scale developments. To overcome these limitations, in this study, through the innovative application of superhydrophobic and superhydrophilic materials, we first fabricated jumping-droplet thermal diodes with a maximum unidirectional heat transfer capacity of 18.24–26.62 times with large dynamic adjustment margins. Then, the performance-adjustable building envelope combined with the jumping-droplet thermal diode was designed. The simulation results showed that the building envelope can achieve 19.81% energy saving in mild climate zones, and the cooling energy saving potential in different climate zones ranges from 12.11 to 22.11%. The adjustment capacity of the new building envelope is 3.34 times that of the traditional dynamic building envelope. This study promotes innovations in the field of building and materials and their simultaneous application, which can provide some practical references for switchable heat transfer building envelopes. • A new switchable building envelope with a jumping-droplet thermal diode is presented. • This advanced building envelope with novel principle can achieve passive heat dissipation. • Cooling energy savings of 12.11%–22.11% can be achieved in different climate zones. • The adjustment capacity of the new building envelope is 3.34 times that of the traditional dynamic building envelope. [ABSTRACT FROM AUTHOR]

• Micropatterned Cu surfaces with apparently improved LM wettability were obtained. • Low TIR was proved to demand low LM dosage meanwhile low trapped air area ratio. • Extra low, stable TIR of 0.37 m m 2 · K / W was attained on optimized surfaces. Thermal management systems are facing significant demand to dissipate increasing heat fluxes in time, however, heat transfer between solid surfaces is always obstructed due to the unperfect interfacial contact. Gallium-based room-temperature liquid metals (LM) are a type of emerging thermal interface materials (TIMs) with superior thermal conductivity and deformability, efficiently enhancing the through-interface thermal transfer. However, the poor wettability of LMs with engineering materials (e.g. , copper), which leads to non-negligible remaining gap/air at the interfaces, limits the further reduction of thermal interface resistance. Herein, a laser micropatterning approach is presented to significantly improve LM wetting behaviors with copper surfaces in the assistance of HCl solution, with the thermal interface resistance minimized to ∼0.37 mm2·K/W which is four orders of magnitudes lower than that of two bare surfaces directly contacted and a quarter of that of bare surfaces with LM as TIM. Micropatterns featuring dense, shallow and open channels were designed and demonstrated to effectively expel trapped air while using a small amount of LM, which were both found necessary for reducing thermal interface resistance. We believe this study can lay a foundation for the further development and practical application of LMs based thermal management strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, an efficient laser surface ablation strategy for producing binder‐free carbon‐coated nanocotton CoO‐Co integrated anode is reported. The fabrication process introduces in‐situ growing nanocotton‐like CoO on the surface of Co foil via ablating with a nanosecond laser. After that, coated with dopamine as carbon source, the CoO‐Co composite foil is heated in Argon atmosphere to form a CoO@C‐Co foil as an anode of LIB. The laser surface ablation exhibits high fabrication speed (~10 minutes) and significantly reduces the processing time. The obtained binder‐free CoO@C‐Co integrated anode shows a unique cotton‐like villous structure with large specific surface area and an active material/current collector integrated architecture, which provides a stabilized rapid electronic conduction path. When tested as an anode for LIBs, the CoO@C‐Co integrated anode possesses superior performance: First discharge capacity of 1301.5 mAh g−1 is achieved at a current density of 0.1 A g−1. Also at a high current density of 1.5 A g−1, the second discharge capacity of 791.7 mAh g−1 is achieved. After 800 cycles, reversible capacities of 799.8 mAh g−1 can still be achieved with an average coulombic efficiency of nearly 100%. In addition, this strategy is suitable for the production of other carbon coated transition metal oxides integrated anodes, such as NiO@C‐Ni, Fe2O3/Fe3O4@C‐Fe, and CuO/Cu2O@C‐Cu integrated anodes. [ABSTRACT FROM AUTHOR]

• Ice-pinning mechanism on superhydrophobic surfaces was revealed. • Anti-ice-pinning strategies were proposed for obtaining robust icephobicity considering structural design. • Anti-ice-pinning superhydrophobic surfaces were developed by ultrafast laser. • The surface showed excellent static anti-icing performances (<0.1 kPa after 1st deicing cycle). • The developed materials can be used for passive anti-icing under static freezing conditions. Micro-nanostructured superhydrophobic surfaces (SHSs) are considered a promising industrial solution to catastrophic ice accretion, e.g., in aviation and powerlines. However, high ice-adhesion strength causes poor icephobicity on SHSs once ice embeds into the valleys among micro-nanostructures, particularly under low-temperature and high-humidity circumstances. Retarding ice-pinning is the key to realizing robust icephobicity, which needs to be made by customizable structures on SHSs. In this study, ice-pinning was identified to occur through liquid penetration, condensation, icing, and frost-filling processes. The ultimate state ice enlarged the grabbing-structure area, directly leading to a high ice adhesion. Specifically, we designed anti-ice-pinning structures comprising micro-scale features, concave sidewalls and heterogenous depths, and nano-scale particles, which were manufactured by an ultrafast laser. The developed anti-ice-pinning SHSs elevate static anti-icing function by the extremely low ice-adhesion strengths (<0.1 kPa after 1st deicing cycle and ∼ 10 kPa after the 30th deicing cycle at an ambient temperature of −20 ℃ and relative humidity of 18 %) and ice-structure interfacial morphologies captured by cryo-SEM. This previously unknown use of anti-ice-pinning strategies and engineering materials to enhance the robust icephobicity contributes to excellent control over ice adhesion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three-region hybrid configuration for extremely-thin vapor chambers was proposed. • Different micro/nano structures were designed and fabricated for three regions. • A short-pulse laser microstructuring approach was developed to fabricate VCs. • Effective thermal conductivity of 12032 W/(m⋅K) was reached for 0.22-mm-thick VC. Efficient thermal management has become a bottleneck for the further development of highly integrated and high-power optoelectronic devices. Vapor chambers (VCs) based on the passive liquid–vapor phase-change process have attracted increasing attention due to their extraordinary thermal management capabilities together with easy-to-assemble advantages. Nowadays, as optoelectronic devices continuously get more compact and miniaturized, there exists a great demand to develop high-performance ultra-thin VCs with overall thicknesses below 0.3 mm. However, the demand has been seldom reached by present VCs with either the layered or spaced configurations. Here, we demonstrated an extremely-thin VC (ETVC) with a three-region hybrid configuration fabricated via a facile laser micro/nano structuring approach, reaching a remarkable effective thermal conductivity of 12032 W/(m⋅K) with an overall thickness of only ∼ 0.22 mm. Cross-arrayed micro-protrusions were fabricated on both the evaporation and condensation regions of the lower plate of the VC, connected by water/vapor passages composed of parallel micro-channels. The micro-channels were designed to make a layered-spaced hybrid configuration to accommodate the fast flow of both water and vapor. The surfaces of both the micro-protrusions and micro-channels were covered with plentiful finer features to render them excellent wicking performances. Such a laser microstructured three-region hybrid configuration enhances all main processes inside a VC (i.e., water evaporation, water condensation, and water/vapor transportation), boosting the self-driven circulation of water/vapor to efficiently homogenize temperature under different heat fluxes. We believe this work can lay a promising rationale for designing and fabricating highly-efficient highly-compact VCs for the increasing thermal management demand within high-end optoelectronics. [ABSTRACT FROM AUTHOR]

Abstract Laser ablation technology is a high-efficient way to fabricate nanomaterials in-situ on the targets. In this paper, we prepare MoO 3 Mo integrated anode through ablation treatment by nanosecond laser and further realize a variety of morphologies of MoO 3 through adjustment of focal length. The electrochemical performances of the new obtained products are notably improved. It exhibits a higher initial Coulombic Efficiency of 85.72% in comparison with the figure of 76.16% before. Moreover, the stable cyclic performance is also extended obviously from 180 cycles to at least 400 cycles, maintaining specific capacity at around 900 mAh g−1. At last, the formation mechanism of MoO 3 Mo with different morphologies are studied. Highlights • MoO 3 Mo integrated anode is fabricated with nanosecond laser in several minutes. • Its electrochemical performance is notably improved through focal length adjustment. • It achieves a high initial Coulombic Efficiency of 85.72%. [ABSTRACT FROM AUTHOR]

The capabilities to reduce light reflection have essential importance for various critical applications. Realistic antireflection surfaces are required to satisfy the comprehensive demands in broadband effectiveness, flexible fabrication, and performance stability. Here, we propose and experimentally demonstrate a type of highly disordered hyper-hierarchical micro-nano structures formed on the surfaces of metals such as Cu, which have the significant capability in absorbing light over the ultrabroadband spectrum from ultraviolet to far-infrared. Average hemispherical reflectance of ∼2.4%, ∼5.5%, and ∼6% is achieved in the wavelength ranges of 400–800 nm, 200–2000 nm, and 2.5–25 μm, respectively, reaching an average absorptance of ∼94% within 0.2–25 μm. The specular reflectance in the long wavelength range of 25–300 μm is also dramatically reduced with respect to the original Cu surface. Such an ultrabroadband antireflection structure is fabricated by a non-contact, maskless, one-step femtosecond laser direct writing approach, making it flexible to be prepared in desired patterns. The hyper-hierarchical structure and its ultrabroadband antireflection property keep robust and stable during harsh aging tests. In addition to the antireflection property, the hyper-hierarchical structure also exhibits excellent self-cleaning performance. All these advantages in ultrabroadband effectiveness, patterning flexibility, structural robustness, as well as self-cleaning, make it promising for practical applications. [ABSTRACT FROM AUTHOR]

The potential applications of superamphiphobic surfaces are widespread and attractive. The design of re-entrant structures is crucial to superamphiphobic surfaces. However, both the existing two strategies to design re-entrant structures face problems. Here a creative strategy to design 3D re-entrant nanostructures on ordered microstructures is proposed. A novel “Top-down” and “Bottom-up” hybrid method consisting of ultrafast laser ablation and chemical bath processing is used to fabricate hierarchical surfaces with 3D re-entrant CuO nanograss on Cu microcones. Thanks to the low surface energy from modification with perfluorodecyltrimethoxysilane and plenty of re-entrant geometries provided by the 3D distributed nanograss structures, the hierarchical surfaces show outstanding superamphiphobicity with water and low surface tension liquid like dodecane. The influence of the nanograss types and the microcone distribution on the superamphiphobicity are systematically studied. Besides, the microcones/nanograss hierarchical superamphiphobic surfaces show excellent long-term durability, high temperature durability and comprehensive mechanical durability, are promising for practically applications. [ABSTRACT FROM AUTHOR]

Abstract The exploration of low-cost and earth-abundant electrocatalysts is crucial to pave the way for hydrogen production through electrocatalytic water splitting. Herein, a 3D self-standing and hierarchical composite with WS 2 nanosheets dotted by CoS 2 nanoparticles is successfully synthesized via the rational structural designing and CoS 2 -incorporating. Edge-oriented WS 2 nanosheets anchored on laser-textured microcone arrays constitute an open and porous framework for highly exposing active edge sites. Meanwhile, CoS 2 nanoparticles are embedded in WS 2 nanosheets to form a strong electronic interaction between them for the synergistic enhancement effect. Thus, the hybrid catalyst exhibits a high hydrogen evolution activity with a low overpotential and small Tafel slope. This study opens up a new pathway to improve electrocatalytic performance via a rational structural design and hybrid incorporation. Graphical abstract Image 1 Highlights • Multiscale structural and CoS 2 -incorporated WS 2 nanosheets are prepared. • Constructing an open and porous framework at the microscale. • Growing edge-oriented WS 2 nanosheets at the nanoscale. • Building a strong electronic interaction between CoS 2 and WS 2. • Free-standing electrodes for HER with effective catalytic activities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabricated an environmentally adapted slippery-superhydrophobic switchable surface. • The constructed surfaces spontaneously adapted to various icing environments. • The constructed surfaces combined anti-ice-pinning and anti-water-pressure properties with durable switchability. • The surface is facilely and large-scale fabricated, showing great potential for practical applications. Numerous state-of-the-art anti-icing surfaces have been developed to avoid undesired icing. However, they generally only work in the single static icing occasion. Under dynamic disturbances, the unstable interfacial states could fail easily, leading to the loss of icephobicity. The impalement of air interfaces on superhydrophobic surfaces and liquids captured by lubricant interfaces are two most known failure mechanisms. How to address these problems and develop a surface with adaptability to changeable harsh environments is of great challenge but of high value. Here we analyze the effects of structural sizes on surface resistance forces and slippery durability and propose a structural design method to balance their relationship. Adopting the optimized structures, we fabricate an environmentally adapted slippery-superhydrophobic switchable surface, which reversibly switches interface states to maintain low adhesion in different environments. We demonstrate that the surfaces show excellent slippery anti-icing properties in static environments and overcome impalement issues. Even in extreme low-temperature environments, a photothermal-assisted droplet self-dislodging is realized. Confronting dynamic disturbances, the superhydrophobic interfaces are spontaneously activated with the broadened anti-water-impact ability (up to 200 kPa). A series of experiments confirm the long-term anti-icing, switchability and universality of our constructed surfaces, which could accelerate practical anti-icing applications in many related fields. [ABSTRACT FROM AUTHOR]

Although transition metal oxides anodes have attracted lots of attention, there are still many problems to be resolved. Complicated fabrication process, high cost and poor electrochemical performances are the most important ones, together hindering transition metal oxides anodes for practical use. Herein, we provide a new approach to fabricate a binder-free and conductive-additive-free TiO 2 /WO 3 -W integrative anode material through the nanosecond laser ablation and dip-coating technology, which simplifies the entire anode preparation process with no need for a conventional tape-casting procedure. Using this method, great time cost, machine cost and labor cost related to mixing and tape-casting process can be saved on the basis of good electrochemical performances. The prepared TiO 2 /WO 3 -W integrative anode realizes a first Coulombic efficiency of 75.6% and attains to a stable capacity within the first five cycles. It can still maintain a capacity of 600 mAh g −1 in the range of 0.01–3 V vs. Li + /Li at a current rate of 0.2 C after 500 cycles. This work offers a new way to achieve a fast fabrication of the integrative anode for lithium ion battery, which is universal for other transition metals (such as Fe, Cu, Ni, Co, Mo, W etc.). [ABSTRACT FROM AUTHOR]

W/Cu joining is key for the fabrication of plasma facing components of fusion reactors, which however is very challenging due to the low bonding strength and high W/Cu interface thermal stress as a result of the immiscible nature of W-Cu binary system and thermal expansion coefficient mismatch between W and Cu. In this paper, we proposed a method for comprehensive enhancement of the mechanical and thermo-mechanical properties of W/Cu joints based on femtosecond (fs) laser fabricated micro/nano interface structures. Four kinds of surface structures, namely pristine structure, nano ripples, micro-cubes and micro-pits were fabricated on W by fs laser ablation and introduced into W/Cu joining interface by hot pressing joining at 1000 °C, 80 MPa. The micro/nano interface structures contribute to significant enhancement of the tensile strength, shearing strength and thermal fatigue life of the W/Cu joints, which reach 101.58 MPa, 186.47 MPa and >800 thermal cycles, increased by about 150%, 320% and 400% compared with W/Cu joints with pristine interface structure. This research provides an approach for enhanced joining between dissimilar materials, including but not limited to W and Cu. [ABSTRACT FROM AUTHOR]

W/Cu joining is key for the fabrication of plasma facing components for fusion reactors, which however is very challenging due to the immiscible nature of Cu-W binary system and the mismatch of thermal expansion coefficient between W and Cu. In this research, we proposed a method for comprehensive enhancement of the bonding strength and heat transfer capability of W/Cu joining based on femtosecond (fs) laser fabricated micro/nano interface structures. Four kinds of surface structures, namely pristine structure, nano ripples, micro-cubes array and micro-pits array were designed and fabricated on W by fs laser ablation, which were then introduced into W/Cu interfaces by hot pressing joining at 1000 °C, 80 MPa. The micro/nano interface structures lead to significant enhancement of W/Cu bonding strength, which reaches 101.58 MPa for W/Cu direct joining and 120.43 MPa for W/Cu joining with Cu interlayer, increased by about 150% and 190% compared with W/Cu joining with a flat interface. The thermal diffusivity and thermal stress resistance of W/Cu joining are also improved. The strengthening mechanism is recognized to be the combined effects of micro/nano interface structures related interdiffusion between W and Cu and increased resistance against W/Cu interfacial debonding. Our research provides a method for enhanced joining between W and Cu, as well as a vast range of dissimilar materials. [ABSTRACT FROM AUTHOR]

Micro/nano surface structures show great significance in both fundamental research and practical applications. Imprinting technique is widely used to fabricate micro/nano surface structures on polymers at low temperature, but barely implemented on metals. In this paper, femtosecond (fs) laser was used to fabricate micro/nano surface structures on tungsten (W), which served as molds for subsequent solid state imprinting process to replicate the counter structures onto copper (Cu) surface at temperature up to 1000 °C. Nano-ripples superimposed on micro-bumps array are fabricated without surface oxidation, and the height of the micro-bumps is adjustable by varying the laser energy input for W molds preparation. The as-prepared Cu surface structures are hydrophobic and turn to superhydrophobic after chemical modification. To demonstrate the feasibility and capability of this technique, similar surface structures were fabricated on A356 aluminum alloy (A356 AA) by liquid state imprinting at 740 °C using M2 steel molds prepared by picosecond (ps) laser ablation. This approach combines the advantages of ultrafast laser ablation to fabricate molds with micro/nano surface structures and high-temperature imprinting process to replicate the micro/nano structures onto target metallic surfaces. It opens new possibility for the mass fabrication of functional micro/nano surface structures on metals. [ABSTRACT FROM AUTHOR]

• A photothermal superhydrophobic surface was prepared using a hybrid laser-chemical method. • The surface showed low sunlight reflectivity (2.69%), high durability and ice repellency. • The surface maintained its properties in a three-month long-term outdoor test in winter. • The surface showed excellent static anti-icing and rapid dynamic de-icing performances. • The surface profile was unchanged during the in-situ fabrication method, convenient for practical use. Ice formation and accretion have a severe negative impact, thus creating the tremendous demand for anti-icing/deicing surfaces. Compared with other techniques, superhydrophobic surfaces possess unique advantages including extremely low affinity to water droplets and reduced ice adhesion strength, whereas their weak durability and failure in cold and moist environments restrict their practical applications. Therefore, photothermal superhydrophobic surfaces possessing high light absorptivity have been proposed, by which ice can be removed by harvesting solar energy as heat eco-friendly and efficiently. However, practical photothermal superhydrophobic surfaces with superior photothermal capability, anti-icing/deicing performance and high durability remain scarce. In this study, a durable cauliflower-like micro-nano structured superhydrophobic surface was produced by combining the ultrafast laser ablation and wet chemical reactions. The hierarchical structures, composed of microcones arrays, in-situ grown cauliflower-like structure and closely bonded PDMS layer, exhibited not only a high absorption rate of 97.3%, but also the high durability in both experimental and natural environment. The temperature raised 48.5 °C under 1 sun illumination for 300 s in ambient conditions. The surface still kept superhydrophobic after several durability tests. The photothermal effect dramatically reduced the ice adhesion strength and deteriorations on the surface during its operation. Under the light intensity of 1 sun for 1 min each cycle, the ice adhesion strength maintained around 10 kPa stably over 40 icing-deicing cycles and the ice layer was melted under 2 min irradiation. Besides, in a three-month long outdoor experiment, the proposed superhydrophobic surface remained its efficient photothermal conversion capacity as well as high durability. Therefore, the cauliflower-like micro-nano structured superhydrophobic surface is one of the most promising methods for anti-icing/deicing applications due to the advantages of superior photothermal capability, long-term durability and adaptability. [ABSTRACT FROM AUTHOR]

[Display omitted] • We developed a high-throughput hydrophobic/superhydrophobic SERS platform. • This platform can detect 10-14mol/L R6G with an enhancement factor of 2.1 × 1011. • One platform can detect at least nine different analytic droplets simultaneously. • This platform has distinguishing ability for CV, MG, MB and their mixtures. • This platform can detect CV residue on contaminated fish scales. Surface-enhanced Raman Scattering (SERS) possesses unique advantages including convenient operation, label free, simple pretreatment process, non-destructive inspection and reliable test results. Aimed at practical applications, the SERS substrates need comprehensive properties in low-cost, rapid detection, high sensitivity, uniformity, stability and universality. Facile fabrication such as laser ablation and high-throughput detection can greatly reduce the cost and improve the detection efficiency. Meanwhile, superhydrophobic surfaces can increase the sensitivity and uniformity via evaporation enrichment. Herein, we report a patterned hydrophobic/superhydrophobic SERS platform, achieving the detection of 10-14mol/L Rhodamine 6G with an effect factor up to 2.1 × 1011 and high-throughput detection for at least nine different samples simultaneously. Notably, considering the abuse of hazardous fish drugs, we further apply this platform to detect crystal violet, malachite green, methylene blue, their mixtures and the crystal violet residue on contaminated fish scales. These results demonstrate that this SERS platform can not only maintain its relatively high sensitivity but also perform excellent distinguishing ability, offering valuable information on the application fields including food safety evaluation. [ABSTRACT FROM AUTHOR]

Corrosion of metals causes tremendous financial loss and disasters every year. Graphene is a promising candidate for anti-corrosion coating, due to its unique properties, e.g. chemical inertness, impermeability and high conductivity. Despite being a commercially important material, it is difficult to grow graphene on carbon steels and is therefore prominently grown on copper or nickel substrates. Here, we report a unique approach to grow graphene on carbon steel and explore its anti-corrosion application. By introducing Ni element into carbon steel through a laser alloying process to form a Ni/Fe alloy catalyst, we make it feasible to grow graphene on carbon steel. The corrosion rate of graphene covered carbon steel is only 0.05 mm/year, much lesser than that of the stainless steel (0.09 mm/year). The corrosion resistance is up to ∼1900 Ω cm 2 , which is almost 7 times that of original steel (270.7 Ω cm 2 ). These results indicate that the in situ grown graphene coatings perform very well in resisting harsh environments, much better than stainless steel itself. [ABSTRACT FROM AUTHOR]

• We developed a chemical-free ultrathin aluminum wick with dual-scale microgrooves. • The wick exhibited an improved K/R eff about 1.322 µm with a depth of about 100 µm. • The enhanced capillary performance was related to the interaction of liquid in each groove. • This wick kept the ability to transport liquid under bending angles of 90 and 135°. With the burgeoning development of electronic devices with higher heat flux, thinner volume, lighter weight, and flexibility, heat pipes and vapor chambers are facing big challenges, especially in fabricating high-performance wicks within limited space. Microgrooves have gained increasing interest for the ability to be directly curved on the substrates, whereas the capillary performance enhancement hits a bottleneck. In this study, a chemical-free ultrathin aluminum wick with dual-scale microgrooves was fabricated via two-step laser texturing in 0.3 mm thick AA6061. The resultant surface, composed of main microgrooves and periodic sub-microgrooves in the ridges and valleys, demonstrated enhanced capillary performance via capillary rise rate experiments. The interaction of liquids in dual-scale microgrooves, that was the pumping effect and the flow resistance reducing effect, would be the main reason for the capillary performance enhancement. The ultrathin aluminum wick with dual-scale microgrooves exhibited a K / R eff about 1.322 µm with a shallow depth of about 100 µm, increased by 11.3% compared with that of single-scale microgrooves due to the assistance of the sub-microgrooves. This wick kept the ability to transport liquid under bending angles of 90 and 135°. Moreover, the wicking performance of different liquids decreased with the decrease of surface tension to viscosity ratio. The ultrathin aluminum wick with dual-scale microgrooves showed enhanced capillary performance, which was among the best with thickness less than 200 µm to our knowledge. This work provides insight into the design of high-performance wicks within limited space and weight. [ABSTRACT FROM AUTHOR]

Laser metal deposition (LMD) additive manufacturing process was applied to produce ultrafine TiC particle reinforced Inconel 625 composite parts. The effects of laser energy input per unit length (LEIPUL) on microstructure development, densification response, and mechanical performance including wear performance and tensile properties were comprehensively studied. A relationship of processing conditions, microstructural characteristics, mechanical performance, and underlying strengthening mechanisms was proposed for a successful LMD of high-performance Inconel based composite parts. It revealed that using an insufficient LEIPUL of 33 kJ/m lowered the densification behavior of LMD-processed parts, due to the appearance of residual large-sized pores in inter-layer areas of the parts. An increase in LEIPUL above 100 kJ/m yielded the near fully dense composite parts after LMD. On increasing LEIPUL, the TiC reinforcing particles became significantly refined and smoothened via the elevated melting of particle surfaces and the dispersion state of ultra-fine reinforcing particles was homogenized due to the efficient action of Marangoni flow within the molten pool. The dendrites of Ni–Cr γ matrix underwent a successive change from an insufficiently developed, disordered microstructure to a refined, ordered microstructure with the increase of LEIPUL. However, the columnar dendrites of the matrix were coarsened apparently at an excessive LEIPUL of 160 kJ/m because of the elevated thermalization of the input laser energy. The formation of the refined columnar dendrites of Ni–Cr γ matrix combined with the homogeneously distributed ultra-fine reinforcing particles contributed to the enhancement of wear performance of LMD-processed composites with a considerably low coefficient of friction (COF) of 0.30 and reduced wear rate of 1.3×10 −4 mm 3 /N m. The optimally prepared TiC/Inconel 625 composite parts demonstrated a ductile fracture mode with a sufficiently high tensile strength of 1077.3 MPa, yield strength of 659.3 MPa, and elongation of 20.7%. The superior tensile properties of LMD-processed parts were attributed to the significant grain refinement effect of the matrix during laser processing and the efficient prohibition of ultrafine reinforcing particles on the mobility of dislocations. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (RGO)/Si Schottky diode has been fabricated by a simple drop-casting/annealing process. Common combustible and/or toxic gases including CH 4 , O 2 , CO, NO 2 , NO, and SO 2 were employed to evaluate the detection performance of such device. The relationship between current response and gas flow rate, concentration, bias voltage as well as operating time has been systematically studied, and the results indicated that the RGO/Si-based device is selective to gases like NO 2 and NO. In some cases ( i.e. flow rate detection), however, the current response for one gas is completely contrary to others, presumably due to the oxygen functional groups (OFGs) presiding on the surface of reduced graphene oxide. Finally, the effects of OFGs on the gas detection performance of RGO/Si-based devices were thoroughly discussed. [ABSTRACT FROM AUTHOR]

We report here a simple and efficient hot embossing process capable of mass fabricating superhydrophobic and self-cleaning polytetrafluoroethylene (PTFE) film surfaces. Adding superhydrophobicity to hydrophobic polytetrafluoroethylene (PTFE) significantly enhances their application potential in industry as well as in daily life. We applied a picosecond laser to fabricate regular array of micro-holes companied with submicron structures on high strength steel substrate to form a lotus-leaf-like template. Then the hot embossing process was performed on flat PTFE films to introduce a dual-scale structure composed of the micro-scale protrusions and nano-scale fibril structures on the top of protrusions. The hot embossing parameters such as the embossing pressure and time were optimized to achieve required micro- and nano-scale dual structure on PTFE film very closed to the similar dual structure of the lotus leaf surface. The PTFE films then exhibited superhydrophobicity with contact angle up to 154.6° and sliding angle of as low as 5.5°. The thermal stability of the superhydrophobic PTFE films was investigated from room temperature up to 430 °C. We demonstrate that the micro–nano dual structure on PTFE films and their superhydrophobicity is thermally stable up to 340 °C. The micro-scale protrusions will collapse and the superhydrophobicity will lose when the temperate is over 370 °C. [ABSTRACT FROM AUTHOR]

Based on isotope labelling, we found that liquid water can afford an ultrafast permeation through graphene-based nanochannels with a diffusion coefficient 4–5 orders of magnitude greater than in the bulk case. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is slightly faster than water, indicating that the ions are mainly transported by water flows and the delicate interactions between ions and nanocapillary walls also take effect in the accelerated ion transportation. [ABSTRACT FROM AUTHOR]

A hybrid heterojunction and solid-state photoelectrochemical solar cell based on graphene woven fabrics (GWFs) and silicon is designed and fabricated. The GWFs are transferred onto n-Si to form a Schottky junction with an embedded polyvinyl alcohol based solid electrolyte. In the hybrid solar cell, solid electrolyte serves three purposes simutaneously; it is an anti-reflection layer, a chemical modification carrier, and a photoelectrochemical channel. The open-circuit voltage, short-circuit current density, and fill factor are all significantly improved, achieving an impressive power conversion efficiency of 11%. Solar cell models are constructed to confirm the hybrid working mechanism, with the heterojunction junction and photoelectrochemical effect functioning synergistically. [ABSTRACT FROM AUTHOR]

Abstract: A fast, simple technique was developed to fabricate few-layer graphene films at ambient pressure and room temperature by laser-assisted chemical vapor deposition on polycrystalline Ni plates. Laser scanning speed was found as the most important factor in the production of few-layer graphene. The quality of graphene films was controlled by varying the laser power. Uniform graphene ribbons with a width of 1.5mm and a length of 16mm were obtained at a scanning speed of 1.3mm/s and a laser power of 600W. The developed technique provided a promising application of a high-power laser system to fabricate a graphene film. [Copyright &y& Elsevier]

Abstract: Direct fabrication of graphene on solid carbon coated nickel surface was realized by laser irradiation at room temperature. High-quality graphene was obtained rapidly, e.g. 28.8cm2/min. Arbitrary patterns designed by computer aided design (CAD) software were fabricated directly on Ni substrates without additional mask or setup. Raman mapping results showed that monolayer/bilayer graphene regions accounted for 64% of the film area. Graphene films exhibited excellent resistance to corrosion. The extremely low corrosion current density and high free corrosion potential in 3.5% NaCl aqueous (aq) solutions showed that the as-produced graphene had a superior anti-corrosion performance. The penetration and precipitation mechanism of carbon into Ni substrate during the fabrication process were also discussed. This approach may reach the scale large enough for practical applications. [Copyright &y& Elsevier]

Laser metal deposition (LMD) additive manufacturing of TiC particle reinforced Inconel 718 composite parts was performed. The influence of laser energy density (LED) on densification, microstructures and wear behaviour of LMD-processed composites was studied. It showed that using a LED of 280 J mm−3 produced ∼5% porosity in LMD-processed composites, caused by the aggregation of reinforcing particles. A further increase in LED above 350 J mm−3 yielded near-full densification. Two categories of reinforcing phases, i.e. the substoichiometric TiCx particles and the in situ (Ti,M)C (M = Mo, Nb and Cr) carbide having 7–10 at% Nb and Mo contents, were formed in the matrix of LMD-processed composites. The TiCx reinforcing particles changed from an irregular poly-angular shape to a smoothened and refined structure as the LED increased. An increase in LED resulted in a larger amount of phase formation and an enhanced degree of crystal growth of the in situ (Ti,M)C reinforcement. The interfacial graded layer with thickness of 0.2–1.2 µm, which was identified as (Ti,M)C (M = Mo, Nb and Cr) carbide with 5–6 at% Mo and Nb contents, was tailored between the TiCx particles and the matrix. At an optimal LED of 420 J mm−3, a considerably low coefficient of friction of 0.38 and resultant low wear rate of 1.8 × 10−4 mm3 N−1 m−1 were obtained in sliding tests, due to the combined strengthening of the interfacial graded layer and the multiple reinforcing phases. The wear resistance decreased at an excessive LED because of the coarsening of reinforcement crystals and the decrease in microstructural uniformity of composites. [ABSTRACT FROM AUTHOR]

Abstract: Laser metal deposition (LMD) was applied to deposit Inconel 718 metal matrix composites reinforced with TiC particles. The influence of laser energy input per unit length on constitution phases, microstructures, hardness, and wear performance of LMD-processed TiC/Inconel 718 composites was studied. It revealed that the LMD-processed composites consisted of γ Ni–Cr solid solution matrix, the intermetallic precipitation phase γ′, and the TiC reinforcing phase. For the laser energy input per unit length of 80–120kJ/m, a coherent interfacial layer with the thickness of 0.8–1.4μm was formed between TiC reinforcing particles and the matrix, which was identified as (Ti,M)C (M=Nb and Mo) layer. Its formation was due to the reaction of the strong carbide-forming elements Nb and Mo of the matrix with the dissolved Ti and C on the surface of TiC particles. The microstructures of the TiC reinforcing phase experienced a successive change as laser energy input per unit length increased: Relatively coarsened poly-angular particles (80kJ/m) – surface melted, smoothened TiC particles (≥100kJ/m) – fully melted/precipitated, significantly refined TiC dendrites/particles (160kJ/m). Using the laser energy input per unit length ≥100kJ/m produced the fully dense composites having the uniformly dispersed TiC reinforcing particles. Either the formation of reinforcement/matrix interfacial layer or the refinement in TiC dendrites/particles microstructures enhanced the microhardness and wear performance of TiC/Inconel 718 composites. [Copyright &y& Elsevier]