Search

Shot peening is a well-known practical method for improving the surface performance of mechanical components. In this work, shot peening was applied to 42CrMo steel components as tie bars for a double platen injection molding machine. The microstructure and morphology of the samples were studied. The residual stress and phase identification of steel samples with and without shot peening were determined by X-ray diffractometer. At the same time, the numerical simulation was carried out and compared with the actual residual stress. Microhardness, mechanical properties, wear and corrosion resistances of the shot-peened samples were studied. The results showed that shot peening treatment influence surface microstructure and properties of the steel. Plastic deformation regions and residual stress layers were formed after shot peening. The presence of these plastic deformation regions, grain refinement, and residual stress layers improved the surface hardness, fatigue life, and wear resistance of the steel. Electrochemical analysis demonstrated a reduction in the corrosion resistance of the steel after shot peening. In order to improve the corrosion resistance of the steel after shot peening, it was subjected to phosphating treatment, and its corrosion resistance performance was studied. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced polymer (CFRP) is an engineering composites with excellent performance. The adhesion strength of nickel layer on CFRP composite was enhanced by pretreatment processes, including sandblasting and activation. The surface roughness, wettability, phase and microstructure of the CRFP and the layer were determined by surface profile-meter, goniometer, X-ray diffraction and scanning electronic microscopy, respectively. The adhesion force of nickel layer on CFRP composite was estimated by 3 M tape and pull-out test. The results showed that electroless nickel layer was composed of crystalline phase with small grain size, which belonged to medium-phosphorus deposits. The sandblasting improved the surface roughness and wettability of CFRP surface and rendered hydrophobic surface hydrophilic. The surface roughness of CFRP composites after sandblasting was enhanced by about 60.2%, at the same time the adhesion strength of the layer metalized CFRP composites after sandblasting was improved by 131%. After 3 M tape test, the adhesion state of nickel-CFRP composites with and without sandblasting could be qualitatively classified as grade 5B and 1B, respectively. The good adhesion of nickel layer on CFRP composite was generated from the increase in the surface roughness of CFRP composites after sandblasting and chemical activation, resulting in hydrogen bonds and covalent bonds. The lightning strike test showed that electroless nickel layer did not provide sufficient protection for the sandblasted CFRP composite when subjected to an big impulse current of up to 40 kA current peak and 8–20 μs duration due to the high electrical resistivity. [ABSTRACT FROM AUTHOR]

This study compares nickel-aluminum (Ni-Al) and 3Cr13 steel coatings deposited on carbon steel substrates by arc spraying. The objective is to select a coating that will improve the corrosion and abrasion wear resistance of boiler heat exchanger pipes. This comparison involves the study of the microstructure, phase composition, microhardness, wear and erosion, and corrosion resistance of the coatings. The corrosion resistance was evaluated based on seawater immersion, electrochemical impedance, polarization, and galvanic corrosion tests. The results showed that the Ni-Al coating had a porosity of 6.3%, while the 3Cr13 coating had a porosity of 5.2%. The average surface roughness of the 3Cr13, Ni-Al coatings, and polished substrate were 11, 14.4, and 0.13 μm, respectively. The 3Cr13 lamellar structure coating was mainly composed of the α-Fe phase and a small amount of the CrO phase, and the Ni-16wt%Al coating included a solid solution phase and a small amount of the NiO phase. During the wear tests, the Cr13 steel coating had the highest microhardness and the best abrasion resistance at room temperature at the initial stage of friction. However, its abrasion resistance was lower than that of the Ni-Al coating after a 10-min friction test. The friction coefficients of the two coatings were almost the same at 300 °C. The corrosion resistance of the Ni-Al coating was better than that of the 3Cr13 steel coating. The current density of galvanic corrosion of the 3Cr13 coating was 108 μA m-2 and that of the Ni-Al coating was 37 μA cm-2, indicating that galvanic corrosion occurred between the substrate and the coating. This comparison showed that the Ni-Al coating could provide better high-temperature abrasion resistance and anti-corrosion performance for boiler heat exchanger piping compared with the 3Cr13 steel coating. [ABSTRACT FROM AUTHOR]

To improve the efficiency of polycrystalline silicon solar cells, process optimization is a key technology in the photovoltaic industry. Despite the efficiency of this technique to be reproducible, economic, and simple, it presents a major inconvenience to have a heavily doped region near the surface which induces a high minority carrier recombination. To limit this effect, an optimization of diffused phosphorous profiles is required. A "low-high-low" temperature step of the POCl3 diffusion process was developed to improve the efficiency of industrial-type polycrystalline silicon solar cells. The low surface concentration of phosphorus doping of 4.54 × 1020 atoms/cm3 and junction depth of 0.31 μm at a dopant concentration of N = 1017 atoms/cm3 were obtained. The open-circuit voltage and fill factor of solar cells increased up to 1 mV and 0.30%, compared with the online low-temperature diffusion process, respectively. The efficiency of solar cells and the power of PV cells were increased by 0.1% and 1 W, respectively. This POCl3 diffusion process effectively improved the overall efficiency of industrial-type polycrystalline silicon solar cells in this solar field. [ABSTRACT FROM AUTHOR]

• Mechanical properties and pitting corrosion resistance of L-PBF 316L steel were studied. • Synergistic relationship among laser power, porosity and pitting of the steel was elucidated. • LOF and keyhole pores were generated from low and high laser powers, respectively. • A model for the mechanism of pitting caused by porosity defects was established. • Pitting easily occurred at the boundaries of melt pools by an in-situ observation system. 316L stainless steel parts were additively manufactured via laser powder bed fusion under different laser powers. We investigated the influence of laser power on the microstructure and mechanical properties of the printed parts by conducting scanning electron microscopy, X-ray diffraction, microhardness and tensile tests. In addition, we performed electrochemical corrosion tests including cyclic potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 wt% NaCl solution to study the influence of laser power on the corrosion behavior of as-printed parts. The results indicate that as-printed parts exhibit a preferential orientation of (2 2 0) direction, and increasing the laser power results in grain refinement of the samples, but excessive laser power can lead to a re-increase in the grain size of the samples. Excessively low laser power can result in the formation of lack of fusion pores, while excessively high power can lead to the formation of keyhole pores. These defects lead to a reduction in tensile performance. Significant differences in corrosion resistance are observed for the parts printed with different laser powers, and between the building direction and normal direction. Some defects, such as micropore, MnS inclusions and boundaries of melt pools, have an impact on the pitting corrosion resistance of printed parts. However, due to low content of MnS inclusions, the presence of pore defects remains the major factor in the pitting corrosion process. Laser powers in the range of 300–375 W can effectively reduce pore defects and improve the resistance of pitting corrosion. These findings emphasize the importance of optimizing the laser power to enhance the overall performance and pitting corrosion resistance of 316L stainless steel parts. [ABSTRACT FROM AUTHOR]

A certain locomotive coil spring was found to fracture prematurely after only 300,000 km of operation. This work employed a combination of experimental and finite element methods to analyze the failure reasons in detail. Firstly, fatigue crack originated from the first working coil adjacent to the support ring, and the fracture exhibited characteristics of low-cycle high-stress fatigue. Secondly, the chemical composition, microstructure, and microscopic morphology of the failed sample was characterized using inductively coupled plasma emission spectrometry, metallographic microscopy, and scanning electron microscopy, respectively. Mechanical properties of the spring were tested using a Rockwell hardness tester and a single-column pendulum-type impact testing machine. Chemical composition analysis of the failed spring indicated conformity to standards. Microscopic fracture analysis revealed quasi-cleavage fracture features, with noticeable fatigue striations and a small amount of ductile dimples were also found. In the absence of corrosion, the microstructure of the spring showed small secondary cracks and deformation marks near the crack source. Microstructures after corrosion revealed predominantly tempered troostite, and the spring's surface underwent an unexpected decarburization process, resulting in a fully decarburized layer with a depth of approximately 64 μm and a total decarburized layer depth of about 160 μm. The overall hardness of the failed spring was below the relevant technical specifications. Furthermore, based on the results of fracture analysis and finite element analysis, it was determined that the spring encountered abnormal conditions during its service period. Therefore, the premature failure of the spring occurred due to the combined effects of unexpected defects resulting from improper heat treatment and adverse service conditions. Finally, some suggestions and preventive measures are proposed for the spring. [ABSTRACT FROM AUTHOR]

Polyetherimide (PEI) composite is an engineering plastic with excellent performance. After metallization, the metalized PEI composite has some unique properties, such as electromagnetic shielding and high electrical conductivity. In this study, a composite coating of Ni/Cu/Ni was produced on the surface of a PEI composite substrate. Nickel and copper layers were plated by electroless and electrodeposition, respectively. The influences of copper interlayer thickness and heat treatment on the adhesion state of the multilayer coatings on the substrate were studied. The morphology and phase of the composite coatings were determined by optical microscopy, scanning electronic microscopy and X-ray diffraction, respectively. The surface roughness and contact angles of the samples before and after sandblasting were measured by surface profile-meter and goniometer, respectively. The electrical resistivity and adhesion state of the composite coatings were determined by multimeter and the tape test, respectively. The results show that Ni/7.54 μm Cu/Ni and Ni/58.6 μm Cu/Ni multilayer deposits were produced on the substrates. The top surface of the coating with a thin 7.54 μm-Cu interlayer was much rougher than that of a coating with a thick 58.6 μm-Cu interlayer. The initial alkaline electroless nickel layer with 5.8 ± 0.5% phosphorus was composed of a mixture of amorphous and nanocrystalline phases. The Cu interlayer consisted of a face-centered cubic crystalline structure. The phosphorus contents of the top nickel layers for samples #1 and #2 were composed of 6.53 ± 0.4 wt% and 3.52 ± 0.21 wt%, respectively. An increase in Cu interlayer thickness for the composite coating resulted in an increase in electrical resistivity. The average microhardness values of Ni/7.54 μm Cu/Ni PEI composite and the Ni/58.6 μm Cu/Ni PEI composite were about 300 HV0.1 and 244.2 HV0.1, respectively. The adhesion state of the Ni/7.54 μm Cu/Ni and Ni/58.6 μm Cu/Ni PEI composites could be classified as grade 5B and 3B, respectively. The adhesion force of the Ni/58.6 μm Cu/Ni multilayer on the substrate can be improved by heat treatment at 200 °C for 4 h. [ABSTRACT FROM AUTHOR]

• The B-doped induced recombination encountered in n-TOPCon solar cells. • B-doped profile divided into two characteristics: peak concentration and junction depth. • Cells with junction depth 0.75–1.0 μm and N max 1–1.5 × 1019 atoms/cm3 exhibited the best I-V. • After the optimization of B emitter, the solar cells reached a pilot efficiency greater than 23.4% A big challenge to improve the conversion efficiency of n-type solar cell is the recombination and electrical contacting of boron (B)-doped emitters in n-TOPCon solar cells. This work investigates the emitter dark saturation current density under the passivation layer (J 0e, passivated), the metallization-induced recombination current density under the metal contact (J 0e, metal), and the I – V parameters, including short-circuit current density (J sc), open circuit voltage (V oc), fill factor (FF) and efficiency (E ff) as functions of the peak concentration (N max) and junction depth of B-doped profile. We introduced the profile with the peak concentration of 1–1.5 × 1019 atoms/cm3 and a junction depth of 0.75–1.0 μm to improve the conversion efficiency of 23.4%. The results revealed that J sc, implied V oc (i V oc) and the contact resistance (ρ c) were negative correlated with the N max and junction depth. However, J 0e, passivated had a positive correlation with the same. The results from ρ c , J 0e along with the I – V showed the junction depth of emitter doping profiles need to exceed the corroded depth of Ag/Al paste to get a low ρ c , meanwhile, a low J 0e should be ensured. The results suggested theB-selective emitters were developed with a low ρ c and a low J 0e. After optimizing B-selective emitters and passivation processes, we obtained industry-grade TOPCon cells with E ff , V oc , J sc , and FF as high as 23.7%, 709 mV, 40.8 mA/cm2, and 82%, respectively. This optimized B-doped and simplified B-selective emitters processes can be commercially applied in photovoltaics. [ABSTRACT FROM AUTHOR]

Thin polysilicon (poly-Si)-based passivating contacts can reduce parasitic absorption and the cost of n-TOPCon solar cells. Herein, n+-poly-Si layers with thicknesses of 30~100 nm were fabricated by low-pressure chemical vapor deposition (LPCVD) to create passivating contacts. We investigated the effect of n+-poly-Si layer thickness on the microstructure of the metallization contact formation, passivation, and electronic performance of n-TOPCon solar cells. The thickness of the poly-Si layer significantly affected the passivation of metallization-induced recombination under the metal contact (J0,metal) and the contact resistivity (ρc) of the cells. However, it had a minimal impact on the short-circuit current density (Jsc), which was primarily associated with corroded silver (Ag) at depths of the n+-poly-Si layer exceeding 40 nm. We introduced a thin n+-poly-Si layer with a thickness of 70 nm and a surface concentration of 5 × 1020 atoms/cm3. This layer can meet the requirements for low J0,metal and ρc values, leading to an increase in conversion efficiency of 25.65%. This optimized process of depositing a phosphorus-doped poly-Si layer can be commercially applied in photovoltaics to reduce processing times and lower costs. [ABSTRACT FROM AUTHOR]

Iridium-based bimetallic alloy system with unique performance is of great interest for high-temperature corrosive environment as a barrier layer or for water splitting of hydrogen/oxygen evolution reactions as a highly efficient and stable electrocatalyst. In this work, iridium-cobalt (Ir–Co) thin films were galvanostatically electrodeposited on a copper (Cu) foam electrode as an electrocatalyst for water splitting in 1.0 M KOH alkaline medium. The effects of loading and solution temperature on hydrogen evolution performance of Ir–Co deposits were investigated. The results show that Ir–Co deposits were adhered to substrates, with porous structure and hollow topography. The concentrations of Ir in the deposits with the loadings of 4.6, 3.2 and 0.8 mg·cm−2 were 88, 88 and 75 wt%, respectively. Ir–Co deposit with the loading of 3.2 mg·cm−2 required an overpotential of 108 mV for hydrogen evolution reaction to reach a current density of 30 mA cm−2, having a low Tafel slope value of 36 mV·dec−1. The changes in the solution temperature and catalyst loading had a significant effect on hydrogen evolution performance of Ir–Co/Ir–Co–O electrocatalysts. With the increasing of catalyst loading, the electrocatalytic activity increased firstly and then decreased. As the solution temperature was increased from 20 to 40 °C, the electrocatalytic activity of Ir–Co–O electrocatalyst increased, and then decreased with the rising of temperature. The apparent thermal activation energy obtained from Arrhenius plot was ~13.9 kJ mol−1. Ir–Co/Ir–Co–O deposits exhibited relatively good electrocatalytic stability and durability. The present work demonstrates a possible pathway to develop a highly active and durable substitute for thin film electrocatalysts for water splitting of hydrogen evolution reaction. Image 1 • Electrodeposition of Ir–Co thin film on copper foam as a high-performance HER electrocatalyst. • Ir–Co catalyst required η = 108 mV at j = 30 mA cm−2 with Tafel slope of 36 mV·dec−1. • Influence of temperature and loading on HER of Ir–Co/Ir–Co–O thin films on Cu foam. • Apparent thermal activation energy obtained from Arrhenius plot was about 13.9 kJ mol−1. • Electrodeposited Ir–Co thin films exhibited good electrocatalystic stability and durability. [ABSTRACT FROM AUTHOR]

• The optimal cleaning process combined inline-HF/HNO 3 and batch-polish solution. • Cells with low I Rev 0.15A have good optical property after optimal cleaning process. • Developed wraparound model addressed the principle of cleaning process. • A pilot efficiency >23.53% of TOPCon cells cleaned with optimal process. The use of tunnel oxide passivated contact (TOPCon) solar cells on the n-type Cz-Si wafers has thus far attracted more interest in the photovoltaics (PV) industry. However, the cells encounter the problems of wraparound appearance and edge leakage current. These phenomena can result in the decrease in the optical and electrical performance of the cells, such as open circuit voltage (V oc), short-circuit current density (J sc), and fill factor (FF). In this work, several cleaning processes were adopted to resolve the problems for cells. The wraparound model and experimental results indicated that an effective cleaning process was carried out and revealed the correlation between the removal of the wraparound film and the edge junction layer on the surface of wafers. The optimized cleaning process did not destroy the boron-doping layer on the front side, and the poly-Si layer on the rear side. This process combined an inline etching process of HF/HNO 3 treatment and a batch-type etching process of the KOH/polish additives solution treatment, which could effectively solve the problems associated with optical properties and achieve a low reversed-biased junction leakage current (I Rev) 0.15 A at −14.5 V. After optimization of the rear surface recombination and the boron diffusion processes, industrial-type TOPCon cells at the present pilot line were obtained with the efficiency (E ff), V oc , J sc and FF of 23.53%, 706 mV, 40.65 mA/cm2 and 82.02%, respectively. This optimized cleaning process could be applied and promoted in the PV industry. [ABSTRACT FROM AUTHOR]

The leakage current phenomenon of a commercial ten-multilayer printed circuit board (PCB) occurred. Preliminary examination shows that there was a short circuit between the PIN_2 and POUT_4 networks of the PCB measured by a high-resistance meter, after a high-temperature aging treatment. In this case, microstructure and morphology of several layers for PCB sample were observed by optical microscopy, scanning electron microscopy and three-dimensional imaging x-ray microscopy. The chemical composition of the layer was determined by energy-dispersive spectroscopy. After observation and analysis, the results show that the leakage current failure cause of the PCB was that the metal powder impurities were found between the layers of PIN_2 and POUT_4 network, which caused the drop in the electric resistance between the two networks, resulting in the occurrence of the leakage current. The chemical composition of the impurity was only composed of copper. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to maraging 18Ni-300 steel fabricate by powder bed based selective laser melting (SLM) process. Microstructure and mechanical properties of the maraging steel part before and after heat treatment at a slow cooling rate were investigated. Design/methodology/approach: The microstructure of the printed part was observed by optical microscopy and scanning electron microscopy. The phases were determined by X-ray diffraction. The surface roughness of the part was recorded by a profilometer. The tensile properties and microhardness of the parts before and after heat treatment were characterized by an electronic universal tensile testing machine and a Vickers hardness tester, respectively. Findings: Maraging 18Ni-300 steel part comprised of the martensitic phase and a small fraction of austenite phase. After heat treatment, the volume fraction of austenite slightly increased. The surface roughness of the part was about 96 µm. The printed part was dense, but irregular pores were present. The yield strength, ultimate tensile strength (UTS), elongation and Young's modulus of as-fabricated parts were 554.7 MPa, 1173.1 MPa, 10.9% and 128.9 GPa, respectively. The yield strength, UTS, elongation and Young's modulus of as-treated parts were 2065 MPa, 2225 MPa, 4.2% and 142.5 GPa, respectively. The microhardness values of surface and cross-section of the as-fabricated part were 407.1 HV and 443.0 HV, respectively. After short-time heat treatment, the microhardness values of the surface and cross-section of the part were 542.7 HV and 567.3 HV, respectively. After long-time heat treatment, the microhardness values of the surface and cross-section of the part were 524.4 HV and 454.8 HV, respectively. The microhardness and tensile strength increased significantly with decreasing elongation due to the changes in phases and microstructure of the parts after heat treatment. Originality/value: This work studied the effect of heat treatment at 550°C combined with a subsequent slow cooling rate on microstructure and mechanical properties of maraging 18Ni-300 steel obtained by the powder bed based SLM process. [ABSTRACT FROM AUTHOR]

Iridium–nickel (Ir–Ni) film is of great interest for catalytic and corrosive environment applications. Ir–Ni thin films as an electrocatalyst for hydrogen evolution reaction (HER) were galvanostatically electrodeposited on copper (Cu) foam from an electrolyte containing 13.5 mM sodium hexabromoiridate(III) and 40.5 mM Ni sulphate hexahydrate, simultaneously compared with electrodeposited Ir and Ni thin films. The top surface morphology of the film was characterized by scanning electron microscopy. The chemical composition of the film was determined by energy-dispersive spectroscopy and X-ray photoelectron spectroscopy. The electrocatalytic performance was performed by linear sweep voltammogram and cyclic voltammetry. The results showed that Ir–Ni thin film adhered to Cu foam and the surface appeared much rougher than the surface of Ni film. The chemical composition of Ir in the deposit was 80 ± 1.2 at.%. The film was composed of nanograins. The top surface of as-deposited film was mainly composed of metallic state. However, the top surface of the film consisted of oxides states, such as Ni oxides or Ni(OH)2, and Ir oxides after electrochemical measurements. As-deposited Ir–Ni thin film with large real active area exhibited high efficient electrocatalytic activity for HER, and achieved a current density of 10 mA cm2 at an overpotential of 60 mV and a Tafel slope of 40 mV dec−1, which is superior to pure Ir and Ni thin films. The remarkable increase in electrocatalytic activity for Ir–Ni film was ascribed to both increased surface area of active centers due to relatively rough and electrocatalytic synergism of Ir and Ni for the HER. Ir–Ni thin film electrodeposited on a foam copper electrode was used as an electrocatalyst for HER. The surface of as-deposited film was composed of metallic state. As-deposited Ir–Ni thin film with large real active area exhibited high efficient electrocatalytic activity for HER, and achieved a current density of 10 mA cm2 at an overpotential of 60 mV and a Tafel slope of 40 mV dec−1, which is superior to pure iridium and Ni thin films. As-deposited film possessed a good stability by accelerated degradation studies. [ABSTRACT FROM AUTHOR]

Rhodium films were electrodeposited galvanostatically on copper–zinc alloy substrates from sulfate–phosphate aqueous solutions, in order to obtain a smooth, dense, and thick Rh film for electrical contacts. The influence of current density and bath temperature on phases, crystal structure, microstructure, and deposition rate of the film was studied. The phases and crystal structure, as well as microstructure of the film were determined by X-ray diffraction and scanning electron microscopy, respectively. The results showed that the current density and bath temperature had a significant influence on electrodeposition of rhodium film. The particles or aggregates on the surface evolved from fine to coarse and large with the increase of current density and bath temperature. By adjusting the deposition conditions, the optimized current density and bath temperature were 6.4–12.7 mA cm−2 and 50 °C, respectively. The film was composed of polycrystalline phase with monometallic form. The film was uniform and dense at low current density. The thickness of the film was up to 1.38–2.1 μm. At the optimal temperature of 50 °C, the surface of the film was smooth and fine. At the same time, the electrodeposition mechanism of the film was discussed. Rhodium films were electrodeposited from sulfate–phosphate aqueous solutions. The influence of current density and bath temperature on electrodeposition of the film was studied, and at the same time, the electrodeposition mechanism of the film was addressed. [ABSTRACT FROM AUTHOR]

In this study, the graphene incorporated into epoxy-polyamide coatings were successfully obtained on carbon steel substrates by spraying process. The corrosion resistance properties of the coatings were investigated, including salt spray corrosion, sea water corrosion and electrochemical corrosion resistance. The results show that the addition of graphene could improve the corrosion resistance properties of the epoxy-polyamide coatings. The coatings in the presence of graphene had better salt spray corrosion than that in the absence of graphene. The surface of the epoxy-polyamide coating exhibited lots of pitting corrosion. The coatings with the addition of graphene showed better sea water corrosion than the coating without graphene. After drying, the epoxy-polyamide coating in the absence of graphene was broken and failed. The coating with 1 wt-% graphene exhibited the best anticorrosion capability as evidenced by the highest corrosion potential and the lowest corrosion current density. The graphene incorporated into epoxy-polyamide coatings were shown to effectively protect carbon steel against corrosion because the graphene nanosheets could be acted as the good chloride ions, oxygen and water molecules barrier. [ABSTRACT FROM AUTHOR]

Nickel–iridium (Ni-Ir) alloy films were electrodeposited from aqueous solutions on copper substrates under galvanostatic conditions. The effects of bath composition and deposition time on the faradaic efficiency (FE), partial current densities, chemical composition, morphology and crystallographic structure of the films were studied. The results show that the Ni–Ir alloys with Ir content as high as 37 at% and FE as high as 44% were obtained. Increase in concentration of citric acid had little or no effect on the composition of the alloys, but resulted in a significant decrease in FE and partial current densities of Ni and Ir. The FE and the partial current density of Ni slightly decreased with increasing Ir 3+ concentration, however, Ir content increased while partial current density of Ir remained stable. The increase of Ni 2+ concentration could result in the increase of the FE and the rate of Ni–Ir deposition, and even no cracks formed on the surface. The surface average roughness and root mean square roughness of the film were 6.8 ± 0.3 nm and 5.4 ± 0.3 nm, respectively. The mixture phases contained significant amounts of Ni oxides and a small amount of metallic Ni, Ir and Ir oxides on the surface. After argon ion sputter cleaning, the film was mainly composed of metallic Ni and Ir. The film consisted of the amorphous and nanocrystalline phases. The Ni content in the deposits was higher than that in the electrolyte, the co-deposition of Ni–Ir alloy was a normal deposition. [ABSTRACT FROM AUTHOR]

When wind turbine is connected to the power grid, the turbine-grid interactions restrict its lifespan and produce adverse effects to the grid. Electrical or mechanical oscillations caused by turbine-grid interactions could gradually be weakened or amplified seriously at a certain frequency. This article discusses all types of interactions between a wind turbine and the grid and the influence of the initial operating point, the parallel capacitor, and the series capacitor on the stability of system. Firstly, an integrated dynamic electromechanical model of a single fixed-speed induction generator (FSIG) wind generation system is derived based on the small signal model of each element. Then, a method of stability analysis based on Kharitonov theorem is introduced. Then, the model details the frequency and damping ratio of oscillation mode and classifies those modes' interactions according to participation factors, followed by time domain simulations by the single FSIG generation system to testify the results. Finally, the article studies all the oscillation modes when the initial operating point, the parallel capacitor, or the series capacitor change in the integrated model, which can be verified by Kharitonov polynomials. The indicative findings help to design the damping control to mitigate turbine-grid interactions. [ABSTRACT FROM AUTHOR]

Ti–6Al–4V alloy parts were obtained by laser powder bed fusion (L-PBF) process. The influence of electrochemically charged hydrogen on the microstructure, phase identification, and mechanical properties of as-charged Ti–6Al–4V alloy parts from printing and deposition directions was studied. The impact of hydrogen desorption on L-PBF Ti–6Al–4V alloy parts was characterized with oxygen nitrogen hydrogen analyzer, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that as-built Ti–6Al–4V alloy was composed of a unique structure of a kind of equiaxed α (hcp) + intergranular β (bcc) dual-phase. The average surface roughness values for R a and R q were 10.1 ± 1.0 μm and 12.6 ± 1.3 μm, respectively. After electrochemically charged hydrogen, the phase in the part was composed of a solid solution of hydrogen in α-phase, and δ-TiH 2 and δ-TiH x hydride phases. The mechanical properties of as-printed Ti–6Al–4V alloy part from deposition direction were higher than those of as-built part from printing direction. After electrochemically charged hydrogen, the hydrogen content in the as-built Ti–6Al–4V alloy part increased significantly. The mechanical properties of the as-charged parts from printing and deposition directions were decreased significantly. The susceptibility to hydrogen embrittlement significantly depended on the orientation of additively manufactured Ti–6Al–4V alloy parts, the as-printed part from deposition direction had a higher resistance to hydrogen embrittlement compared with printing direction. After electrochemically charged hydrogen, Ti–6Al–4V alloy parts from printing direction was prone to brittle fracture and form the microcracks in α phase or along α/β interface in the as-built part. [ABSTRACT FROM AUTHOR]

Ni–Re alloy coatings with Re-content of 0–80 wt% were plated by electrodeposition from Watts's type and citrate solutions by changing deposition parameters. The microstructure, crystallographic texture, deposition rate, grain size, microhardness and abrasion resistance of the alloys were studied. The results showed that the cross-section of Ni–Re alloys with low Re-content of 5–41 wt% was dense and homogeneous. However, the cross-section of the alloys with high Re-content of 55–80 wt% showed the microcracking penetrated through the entire coating thickness. With the increase of Re-content, the coatings were composed of fine nanocrystalline structure, and the grain size decreased, even the coating with 36–80 wt% Re comprised amorphous and nanocrystalline structure. The deposition rate of the deposit from citrate solution was higher than that of the coating from Watts's solution. The coatings obtained from Watts's solution exhibited (220) preferential orientation, however, the deposits produced from citrate solution showed oriented-(111) crystal plane. The microhardness of Ni–Re alloys gradually increased with the increase of Re-content in the deposits. The wear coefficient of Ni–Re alloys gradually decreased with the increase of Re-content. Ni–Re alloy coating with 80 wt% Re exhibited the best abrasion resistance, and had the lowest wear coefficient of about 6.2 × 10−16 m3 m−1 N−1. • Ni–Re alloy coatings with Re-content of 0–80 wt% were plated by electrodeposition. • Ni–Re coating with 36–80 wt% Re comprised amorphous and nanocrystalline structure. • The alloys from Watts and citrate solutions exhibited (220) and (111) orientation respectively. • The microhardness of Ni–Re alloys gradually increased with the increase of Re-content. • The grain size and wear coefficient of Ni–Re alloys decreased with the increase of Re-content. [ABSTRACT FROM AUTHOR]

In this study, Re-Ni alloys with high Re content were electrodeposited on copper substrates from aqueous solutions containing additives with a combination of vanillin, sodium lauryl sulfate and gelatin. The bath additives were found to have a significant effect on the chemical composition, surface morphology and cracking pattern. The morphology of the alloy was changed from uniformly smooth without additives to relatively coarse-grained with three additives. The deposition rate and crack density decreased when additives were added to a bath containing 34 mM ReO 4 − , 124 mM Ni 2 + and 343 mM [Cit] 3 − . Almost pure Re films were formed at low Ni 2 + concentration of 30–50 mM due to the effect of additives; however, the deposited film was thin. A thin layer of Re oxide, a new Re-O-C-complex state and some organic residues from additives were formed at the surface of the Re film. Both the Re-rich alloy and the Re film were found to have an amorphous structure. [ABSTRACT FROM AUTHOR]

• Sodium hexabromoiridate(III) was used for the electroplating of Ir–Ni and Ir–Re–Ni alloys. • Ternary alloys with Ir-contentand Faraday efficiency as high as 31 at% and 100 % were obtained. • Ir-content in the alloys from the bromo system was higher than that from the chloride system. • Electrodeposition mechanisms for Ir-based alloy coatings from the bromo system were proposed. Ir–based alloy materials are of great interest for high temperature, extreme environment and special applications. In this work, Ir–Ni and Ir–Re–Ni alloy coatings were electroplated from aqueous solutions. As the choice of iridium (Ir) compound is crucial to obtain good Ir–based alloys by electrodeposition, sodium hexabromoiridate(III) was added as Ir salt in the electrolyte, in order to obtain high-quality Ir–based alloys with high Ir-content. The bath chemistry consisted of sodium hexabromoiridate(III), sodium perrhenate and nickel(II) sulfate heptahydrate as electroactive species, and citric acid as complexing agent. The effects of bath composition and plating time on the chemical composition, surface morphology, Faraday efficiency (FE), and crystallographic phases of Ir–Re–Ni alloy coatings were studied. The surface morphology, elemental composition percentage and crystallographic phases of the prepared coatings were analyzed with a scanning electron microscopy, X–ray energy dispersive spectroscopy and X–ray diffraction techniques, respectively. Ir–Re–Ni alloys with Ir-content as high as 31 at%, Re-content as high as 63 at%, and a FE as high as 100 % were obtained. The Ir-content in Ir–Ni and Ir–Re–Ni alloys from the bromo electrolyte system was higher than that from the chloride electrolyte system, although the (Re+Ir)-content in the ternary alloys was almost kept the same for two systems. The electrochemical deposition mechanisms for Ir–Ni and Ir–Re–Ni alloys deposited from the bromo electrolyte system were investigated. [ABSTRACT FROM AUTHOR]

Iridium is one of the most promising candidates for protective barrier of refractory materials to endure high service temperature. The multilayer iridium coating was produced by a double glow plasma process on the polished tungsten carbide substrates, compared with monolayer. The ablation behaviors of the monolayer on the unpolished and polished substrates were investigated under carburizing and oxidizing oxyacetylene flames, respectively, at the same time the multilayer coating ablated under oxidizing flames. Multilayer coating was a polycrystalline phase with the preferential (220) orientation. Monolayer on the unpolished substrate had fine coarse grains and some small microcracks were present. Multilayer consisted of columnar grains with some voids between the grains boundaries. The formation of a WIr phase in the as-deposited multilayer was attributed to high deposition temperature. The monolayer could endure high temperature up to 1800 °C in carburizing flame. The substrates could be protected more effectively by multilayer than monolayer at 2000- 2200 °C in oxidizing flame. [ABSTRACT FROM AUTHOR]

In this study, a multilayer iridium coating was processed on niobium substrate by double glow plasma technology. The coating was ablated under an oxyacetylene flame at a temperature up to 2000°C. The oxidation behavior and the failure mechanism of the ablated coating were investigated. The surface and fracture surface morphology were examined by means of scanning electron microscopy. The phase composition was identified by X-ray diffraction. The element analysis was determined by energy dispersive spectroscopy. The results show that many micropores were present on fracture surface and surface. The porosities on the surface of multilayer and monolayer after ablation were about 0.55% and 2%, respectively. The niobium substrate ignited to form masses of gaseous oxide under an oxyacetylene flame. The multilayer iridium coating for protecting niobium substrate from ablation was deteriorated due to effects of the underdense coating, volatile gas and interdiffusion between the coating and the substrate. [ABSTRACT FROM AUTHOR]

Abstract: (110)-Oriented Ir coating was prepared by double glow plasma technique on (200)-oriented Nb substrate. The microstructure of the coating was observed by scanning electron microscopy (SEM). The crystal orientation of the coating was determined by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The coating was composed of columnar grains with submicrometer size of 0.2–0.3μm. The thickness of the coating was approximately 6–7μm. The mean misorientation angles of the surface of the coating were about 38.6°. The columnar Ir coating had a preferential growth orientation of (110) crystal plane by XRD and EBSD due to the initial nuclei with preferred growth on the surface of the substrate. The vigorous bombardment from the high energy ions prevented the lower energy (100) crystal face and the lowest energy (111) crystal face from generating the orientation. Only the highest energy (110) crystal face could be formed and grew up, which resulted in the preferred (110) orientation. [Copyright &y& Elsevier]

In this paper, a platinum coating was deposited on titanium alloy substrate by a double glow plasma. Phase and microstructure of platinum coating were examined by X-ray diffraction and scanning electron microscopy, respectively. The microhardness of the coating was estimated by nanoindentation instrument. The adhesive force between the coating and the substrate was performed with scratch tester. The electrochemical behavior of the platinum coating in 3.5 wt % sodium chloride solution was investigated by potentiodynamic polarization. The results indicated that an adherent platinum coating could be successfully obtained on titanium alloy substrates. Compared with the titanium alloy substrate, the platinum coating had a relative low corrosion current density and high corrosion potential. It indicated that the platinum coating had a better corrosion resistance than the titanium alloy substrate. [ABSTRACT FROM AUTHOR]

Abstract: Zirconium carbide doped carbon/carbon (ZrC–C/C) composites were prepared by the polymer impregnation and pyrolysis process. Carbon fiber preforms were firstly immersed into zirconium acetate solution/phenolic resin impregnant, and then carbonized at 1000°C. After four cycles of impregnation/carbonization, they were finally graphitized at 2000°C. The phase composition of the composites was examined by X-ray diffraction. Microstructural characterization of the composites were investigated by scanning electron microscopy and transmission electron microscopy. The results indicated that ZrC particles with sub-micron size were well dispersed in carbon matrix. ZrC particles were encapsulated by highly oriented carbon, and there existed a well bonded interface between ZrC particles and highly oriented carbon. The formation mechanism of the encapsulated structure was proposed. [Copyright &y& Elsevier]

Abstract: Iridium coating was produced on various substrates using a double glow plasma. The effects of bias voltage and gas pressure on orientation and microstructure of the coating were studied. The orientation, microstructure and composition of the coating were evaluated by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results showed that iridium coatings on various substrates all exhibited the preferred (220) orientation under the same deposition conditions. The microstructure of the coating was affected by bias voltage, gas pressure and substrate effects. The bias voltages had a significant impact on the crystal orientation of the coating. The increase of bias voltage resulted in high substrate temperature and large deposition rate. An increase in the coating thickness can affect the microstructure and orientation of the coating. [Copyright &y& Elsevier]

Abstract: Oxidation protection of carbon material under ultra-high temperature is a serious problem. In this paper, a newly designed multilayer coating of W/Ir was produced onto the graphite substrate by double glow plasma. As comparison, the Ir single-layer coating on the graphite was also prepared. The ablation property and thermal stability of the coatings were studied at 2000°C in an oxyacetylene torch flame. Ablation tests showed that the coated graphite substrates were protected more effectively by W/Ir multilayer coating than Ir single-layer coating. Ir single-layer coating after ablation kept the integrality, although there was a poor adhesion of the Ir coating to the graphite substrate because of the thermal expansion mismatch and the non-wetting of the carbon by Ir coating. The mass loss rate of the W/Ir-coated specimen after ablation was about 1.62%. The interface of W/Ir multilayer coating and the graphite substrate exhibited good adherence no evidence of delamination after ablation. W/Ir multilayer coating could be useful for protecting graphite in high-temperature application for a short time. [Copyright &y& Elsevier]

Abstract: Dense and adhesive iridium coating was obtained on the carbon/carbon composites by double glow plasma. The coating was ablated by an oxyacetylene torch to determine the stability of the coating at 2000°C. Although some pores and the rumpling appeared on the surface after oxyacetylene flame, the integrality and adhesion of the coating kept up. The rumpling could be attributed to plastic deformation of iridium coating which resulted from expansion or contraction mismatch of the coating and the substrate. The ablation results indicated that iridium coating by double glow plasma could afford the high temperature up to 2000°C and protect the carbon/carbon composites from quick oxidizing. [Copyright &y& Elsevier]

Nanocrystalline nickel coatings were electroplated from a Watts-type bath with the addition of H 3 BO 3 ranging of 5–25 g·L−1. In order to study the evolution of preferential orientation of Ni electrodeposits, the microstructure, texture and grain size of the coatings deposited with different H 3 BO 3 contents for different plating times were characterized by optical microscopy, scanning electron microscopy and X-ray diffraction, further the residual stress, microhardness, and abrasion resistance of the texture-oriented coatings were measured by X-ray diffraction, Vickers microhardness tester, and Calotester, respectively. The electrochemical corrosion resistance of the highly texture-oriented coatings and the substrate was evaluated by polarization and electrochemical impedance spectroscopy. The results show the preferential orientation of the coating was gradually changed from (200) to (220) crystal plane with increasing H 3 BO 3 content after plating time of 1 h. The longer the plating time was applied, the higher the degree of Ni (200) orientation was produced at a low H 3 BO 3 concentration of 5 g·L−1. The preferential orientation of the coatings at a high H 3 BO 3 concentration of 25 g·L−1 was changed initially from (111) + (200) to (200) plane, then random orientation, and evolved to (220) plane after plating time of more than 20 min. The stability of various textures of Ni electrodeposits against plating time-H 3 BO 3 concentration was established, and at the same time the microstructure-property relationship was developed. The average grain size of nickel coating was about 50–65 nm. The average residual stresses of the coatings with (200), (200) + (220) and (220) orientations were −64.3 ± 5 MPa, −477.2 ± 57 MPa and −618.0 ± 36 MPa, respectively. The microhardness of the coating increased gradually from 242.52 ± 10HV1 to 269.46 ± 12HV1 with increasing H 3 BO 3 content because of the inverse Hall-Petch and grain orientation. The abrasion and corrosion resistances of (200)-oriented coatings were better than those of (220)-oriented coatings. • Effects of H 3 BO 3 content and plating time on texture and morphology of Ni coatings were studied. • The microstructure-property relationship was developed. • The average residual stresses of the highly texture-oriented coatings were evaluated. • The microhardness of the coating increased gradually with increasing H 3 BO 3 content. • The (200)-oriented coating exhibited good abrasion and corrosion resistances. [ABSTRACT FROM AUTHOR]

Iridium coating was prepared by the double glow plasma. The phase identification and the microstructure observation of the fracture surface of the coating were examined by X-ray diffraction and scanning electron microscopy, respectively. The deposition rate of the coating was up to 20µm/h. The iridium coating failed predominantly by grain boundary brittle fracture at room temperatures. Brittle intergranular fracture does not depend on grain size. Intergranular fracture in iridium coating has been considered to arise from low cohesive strength of the grain boundaries. [ABSTRACT FROM AUTHOR]

Although tricalcium silicate (TCS)-based cement showed a great clinical success as the dental filling material, a big challenge encountered by TCS is its poor anti-washout property. Thus, the purpose of this study is to develop a novel TCS-based cement with excellent anti-washout ability by incorporation of konjac glucomannan (KGM)/calcium formate (CF) complex. The self-setting characteristics, anti-washout ability, setting time, compressive strength, porosity, injectability and flowability of the cements were investigated. Furthermore, antibacterial property and cell cytocompatibility of TCS/CF were also assessed. The results showed that KGM could enhance the washout resistance of TCS pastes while it hindered hydration reaction. CF can further increase the anti-washout ability of TCS cement and shorten its setting time from 420 to 174 min because of the accelerating effect of CF on hydration kinetics of TCS. Compared with TCS pastes, TCS cement containing CF showed an increased compressive strength while the addition of CF decreased the injectability of pastes without an obvious effect on flowability. The antibacterial activity of TCS/CF against S. aureus increased with the amount of CF. Moreover, TCS/CF had good cell cytocompatibility. Our results suggested that incorporation of KGM/CF is a superior strategy to enhance the anti-washout ability of TCS-based dental cements, which have the potential use for endodontic applications. [ABSTRACT FROM AUTHOR]

M-iridium (M = cobalt (Co), nickel (Ni)) bimetallic alloy catalysts with low iridium (Ir) loading of 0.3–2.0 mg·cm−2 were prepared on copper foam (CF) supports by electrodeposition. The top surface of as-deposited M-Ir catalysts was mainly composed of metallic state and oxides states, such as metallic Ir, Ni(OH)2 or Co(OH)2, Co(Ir) and Ni(Ir) solid solution, Ir oxides. M-Ir catalysts with low Ir loading exhibited excellent catalytic performance. Ni63.4Ir36.6/CF catalyst with low Ir loading of 1.8 mg·cm−2 achieved a current density of 10 mA·cm2 at an overpotential of 52 mV and a Tafel slope of 36 mV·dec−1. Co64.2Ir35.8/CF catalyst with low Ir loading of 0.7 mg·cm−2 was uniformly scattered with small ellipsoidal particles, looking like fine fluff, requiring an overpotential of 51 mV for hydrogen evolution reaction to reach a current density of 10 mA·cm−2, having a Tafel slope of 38 mV·dec−1. After long-term hydrogen evolution testing, M-Ir/CF catalysts exhibited excellent electrocatalytic stability for water splitting in alkaline solution. [ABSTRACT FROM AUTHOR]

The tunnel oxide passivated contact solar cells (TOPCon) on n-type Cz Si wafers instead of passivated emitter and rear solar cells are currently migrated to mainstream production, with ongoing improvements in recent years. In this study, we investigated and characterized one recent batch of TOPCon cells fabricated on 156.75 × 156.75 × 0.18mm3 wafers with fully screen-printed technology by an industrial-type process. TOPCon cells with an efficiency as high as 22.43%, a Voc value as high as 689.4 mV, and a fill factor as high as 81.35% were obtained. The P dopant diffusion in the poly Si layer as well as the thickness of the SiO x layer were optimized in order to obtain good electrical contact between screen-printed Ag and Si. The thickness of the SiO x layer should be over 1.5 nm, which is beneficial for obtaining a good passivation for the cells. The surface P dopant concentration in the polycrystalline Si was higher than 1 × 1020 atom/cm3, resulted in a low series resistance and a high fill factor. The characterization and simulation results show that both metal shading loss and rear surface recombination were dominant among all of the losses. Application to solar cells with a Voc of 697 mV and a fill factor of 82.45% could lead to an independently confirmed cell efficiency of over 23% for n-type cells with poly Si the herein developed passivated rear contacts, and the front metal contacts by addressing the issue of reducing metal recombination and implementing a selective emitter. • One batch of TOPCon solar cells fabricated by the industrial type process. • Comparison of different SiO x layer thickness for TOPCon solar cells. • Cells with SiO x layer thickness of 1.55nm exhibited the best passivation effect. • Eff, Voc and FF as high as 22.43%, 689.4mV, and 81.35% were obtained, respectively. • Metal shading loss and rear surface recombination were dominant. [ABSTRACT FROM AUTHOR]

• A batch of fire detectors was corroded under containing sulfur atmosphere. • Some defects and corrosion products with nickel sulfate and its hydrate were present. • The layer consists of two-phase region with different chemical compositions. • The failure model of electroless Ni-P layer was established. A batch of fire detectors used in the aircraft has been corroded under containing sulfur atmosphere. The fire detector was made of guide rods, seat plate, bimetallic strips, ring gasket, moving contact part and spring part. The former three components were deposited with electroless nickel-phosphorus layer. The morphology and microstructure of surface and cross-section of the layer were characterized by optical microscopy and scanning electronic microscopy. The chemical composition and phases of corrosion products were determined by energy dispersive spectrometer and X-ray diffraction, respectively. The results show that the corrosion products were mainly composed of nickel sulfate and its hydrate, indicating the layers aggravated by sulfur substances or compounds. The surface of the layer exhibited lots of microdefects, including pitting, microcracking and micropores. The failure causes of fire detectors under corrosive environments were further addressed and discussed. The failure model of electroless nickel-phosphorus layer was also established. [ABSTRACT FROM AUTHOR]

At the initial rolling temperature of 400 °C, ZK60 magnesium alloy was hot rolled by three different rolling paths with different roll speed ratios (RSR) of 1:1.15, 1:1.2, and 1:1.5, respectively. The effects of different rolling processes on the microstructure and mechanical properties of the alloy were studied. The microstructure, plasticity, strength, hardness, and texture intensity of rolled samples were analyzed in this work. The results show that the microstructure uniformity of the alloy under multi-path asynchronous rolling (MAR) is significantly improved, which improves the mechanical properties of the material to a certain extent, and effectively weakens the texture intensity of the basal plane and reduces the anisotropy. The amount of randomly oriented grains of ZK60 magnesium alloy rolled by the C-1.5 (path C combined with the RSR of 1:1.5) process are significantly increased, which significantly weakens the basal texture and improves the ductility of the alloy, greatly enhancing the processing and formability of ZK60 magnesium alloy. [ABSTRACT FROM AUTHOR]

Electroless nickel–phosphorus (Ni–P) films were produced on the surface of p-type monocrystalline silicon in the alkaline citrate solutions. The influences of bath chemistry and plating variables on the chemical composition, deposition rate, morphology, and thermal stability of electroless Ni–P films on silicon wafers were studied. The as-deposited Ni–P films were almost all medium- and high-P deposits. The concentrations of Ni2+ and citric ions influenced the deposition rate of the films but did not affect P content in the deposits. With increasing H2PO2− content, the P content and deposition rate were steadily increased. The pH and plating temperature had a significant effect on the chemical composition and the deposition rate of the films. The thermal stability of the medium-P film was better than that of the high-P deposit. At the same time, the proposed mechanism of Ni–P films on monocrystalline silicon substrates in the alkaline bath solution was discussed and addressed. [ABSTRACT FROM AUTHOR]

In this work, we conducted a comparative study on water vapor (H 2 O) process and hydrogen gas (H 2) process to prepare the IMO:H films based on industrialized DC magnetron sputtering system. To dynamically control the residual H 2 O pressure, we installed a set of polycold coil and kept it turned on during the sputtering process. The film characteristics of Hall mobility, carrier density, sheet resistance, and transparency was investigated. The results revealed that the silicon heterojunction (SHJ) solar cell with H 2 process had a higher Hall mobility and greater transparency in the 400–600 nm wavelength range resulting in a lower contact resistivity and a slight increase current density compared to the H 2 O process. The median efficiency (E ff) achieved with the H 2 process improved by 0.09% absolute to 25.43%, mainly because of the increased J sc and FF. And the IMO:H films with H 2 process had a large basal spacing with (400) and (222) crystal planes resulting in maintaining a more stable and reliable structure at temperatures below 200 °C. After the optimization of TCO layer process, we manufactured the industrial-grade SHJ cells with max efficiency (E ff), V oc , J sc , and fill factor (FF) values as high as 26.27%, 753 mV, 41 mA/cm2, and 86%, respectively. The IMO:H films with H 2 process can thus be considered more suitable for large-scale production. • The In 2 O 3 :H films with H 2 process had a large basal spacing with (400) and (222) crystal planes. • The ITO films based on H 2 and H 2 O processes were investigated. • Cells with the H 2 processes exhibited better optical and electrical properties. • A industrial-grade max efficiency 26.27% of cells treated with optimized H 2 process. [ABSTRACT FROM AUTHOR]

Decarbonization of transportation sector is critical to achieve net-zero emissions economy by 2060. It is of importance to develop highly efficient electrocatalysts for decarbonization. Ni-Mo-P ternary alloy catalysts were electrodeposited on Cu foam (CF), and the rough surface of Ni-Mo-P/CF catalysts was composed of uniformly dense small clusters with the size of 200 nm. The catalyst was composed of a mixture of nanocrystals and amorphous, with metallic Ni and its solid solution, Ni and Mo oxides, and Ni(OH)2. The Ni70.2Mo27.0P2.8/CF catalyst exhibited Tafel slope of 63.1 mV·dec−1 in alkaline medium, and delivered a current density of 10 mA·cm−2 at an overpotential of 68 mV, demonstrating the excellent hydrogen evolution reaction (HER) activity due to the large active surface area, the synergistic effect and high electrical conductivity of the electrode. After 1000 cycles testing, Ni70.2Mo27.0P2.8/CF catalyst showed an increase of 2.8 mV in hydrogen evolution overpotential and almost no voltage decay was present in chronopotentiometric test for 10 h. The good HER performance of Ni-Mo-P/CF catalysts had a significant potential to be utilized in commercial water electrolyzer.Graphical Abstract: Decarbonization of transportation sector is critical to achieve net-zero emissions economy by 2060. It is of importance to develop highly efficient electrocatalysts for decarbonization. Ni-Mo-P ternary alloy catalysts were electrodeposited on Cu foam (CF), and the rough surface of Ni-Mo-P/CF catalysts was composed of uniformly dense small clusters with the size of 200 nm. The catalyst was composed of a mixture of nanocrystals and amorphous, with metallic Ni and its solid solution, Ni and Mo oxides, and Ni(OH)2. The Ni70.2Mo27.0P2.8/CF catalyst exhibited Tafel slope of 63.1 mV·dec−1 in alkaline medium, and delivered a current density of 10 mA·cm−2 at an overpotential of 68 mV, demonstrating the excellent hydrogen evolution reaction (HER) activity due to the large active surface area, the synergistic effect and high electrical conductivity of the electrode. After 1000 cycles testing, Ni70.2Mo27.0P2.8/CF catalyst showed an increase of 2.8 mV in hydrogen evolution overpotential and almost no voltage decay was present in chronopotentiometric test for 10 h. The good HER performance of Ni-Mo-P/CF catalysts had a significant potential to be utilized in commercial water electrolyzer. [ABSTRACT FROM AUTHOR]

Despite the clinical success of tricalcium silicate (TCS)-based materials in endodontics, the inferior handling characteristic, poor anti-washout property and slow setting kinetics hindered their wider applications. To solve these problems, an injectable fast-setting TCS/β-tricalcium phosphate/monocalcium phosphate anhydrous (β-TCP/MCPA) cement was developed for the first time by incorporation of hydroxypropyl methylcellulose (HPMC) and β-TCP/MCPA. The physical-chemical characterization (setting time, anti-washout property, injectability, compressive strength, apatite mineralization and sealing property) of TCS/(β-TCP/MCPA) were conducted. Its hydration mechanism was also investigated. Furthermore, the cytocompatibility and osteogenic/odontogenic differentiation of stem cells isolated from human exfoliated deciduous teeth (SHED) treated with TCS/β-TCP/MCPA were studied. The results showed that HPMC could provide TCS with good anti-washout ability and injectability but slow hydration process. However, β-TCP/MCPA effectively enhanced anti-washout characteristics and reduced setting time due to faster hydration kinetics. TCS/(β-TCP/MCPA) obtained around 90 % of injection rate and high compressive strength whereas excessive additions of β-TCP/MCPA compromised its injectability and compressive strength. TCS/(β-TCP/MCPA) can induce apatite deposition and form a tight marginal sealing at the dentin-cement interface. Additionally, TCS/(β-TCP/MCPA) showed good biocompatibility and promoted osteo/odontogenic differentiation of SHED. In general, our results indicated that TCS/(β-TCP/MCPA) may be particularly promising as an injectable bioactive cements for endodontic treatment. • High-performance TCS/(β-TCP/MCPA) was fabricated with HPMC and β-TCP/MCPA. • Hydration mechanism of TCS/(β-TCP/MCPA) cements was proposed. • Incorporation of 10 wt% β-TCP/MCPA increased physicochemical properties of TCS. • TCS/(β-TCP/MCPA) can induce apatite deposition and form a tight marginal sealing. • TCS/(β-TCP/MCPA) showed good biocompatibility and osteo/odontogenic potential. [ABSTRACT FROM AUTHOR]

In this paper, chemically bonded phosphate ceramic coatings with different thickness were prepared through sol-gel method. Aim of this paper is to model and simulate the wear process for coating with different thickness by finite element method (FEM) and to compare its results with the experimental wear results. Results show that coating thickness plays a significant role in the wear performance of the coating. The wear rate decreases with the increase in coating thickness. Through transient finite element simulation, it is found that the equivalent stress of the coating decreases with the increase in coating thickness. In particular, increasing coating thickness can significantly decrease the equivalent plastic strain of the coating-substrate system. The reason is that the equivalent hardness and fracture toughness of the coating-substrate system increase with the increase in coating thickness, which effectively enhances the ability of the coating to resist external pressure, reduces the generation and extension of cracks, and prevents the coating from being easily damaged. [ABSTRACT FROM AUTHOR]

The impact of the addition of TiO 2 nanoparticles and nanowires on the morphology, phase characteristics, contact angle, and electrochemical performance of chemically bonded phosphate ceramic coatings (CBPCs) was investigated. The chemical composition and surface morphology of the TiO 2 nanoparticle and nanowire modified with and without (heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane were characterized. Results indicated that the hydrophobic –CF 2 – and –CF 3 groups were successfully introduced into the TiO 2 nanoparticles and nanowires after modification. Corrosion resistance of CBPCs with TiO 2 was evidently improved compared with that without TiO 2. Such improvement was mainly due to the combined effects of low surface energy materials and micro/nano structures. In addition, CBPCs with TiO 2 nanowires exhibited higher hydrophobicity and corrosion resistance than those with TiO 2 nanoparticles because of the special columnar structure of the nanowires. [ABSTRACT FROM AUTHOR]

Hydrogen (H) passivation is one of ideal candidates to reduce interfacial and bulk defects for providing good passivation by the light soaking process. Herein, we investigate the influence of the medium-temperature light soaking process on the passivation and electronic performance of the N-TOPCon solar cells. The medium-temperature light soaking process had the significant impact on the metallization-induced recombination of the p++ layer and the Si substrate with a corroded silver (Ag) at a depth of >165 nm. During the light soaking process, the breaking the bending of (Si:H 2) n bonds causes H transitions from a bound state in the Si–H bond to a free state. In this state, H captures movable Ag and boron atoms on the wafer's surface for passivation. The mechanism for enhancing the passivation on the metallization-induced recombination under the metal contact (J 0 , metal) of SiO x /n+-poly-Si layer, the emitter dark saturation current density under the passivation layer (J 0) of p+ layer, and SiO x /n+-poly-Si layer is to prevent the formation of new defects by removing excess H. An efficiency gain of 0.87 % was observed after the light soaking process, attributed to the increase in open circuit voltage (V oc), short circuit current density (J sc), and fill fact (FF) values by 10 mV, 0.15 mA/cm2, and 1.5 %, respectively. The partial gain of FF comes from the effect of medium-temperature enhanced metal contact. This research contributes to a profound understanding of the mechanism behind improving the medium-temperature light soaking process improvement and offers a feasible strategy for enhancing the efficiency N-TOPCon solar cells. After optimizing the front surface recombination and the medium-temperature light soaking processes, we manufactured industrial-grade TOPCon cells with in-house efficiency (E ff), V oc , J sc , and FF values as high as 25.8 %, 729 mV, 42.1 mA/cm2, and 84 %, respectively. • Light Soaking process is one of ideal candidates of Hydrogen passivation. • J 0 , J 0 , metal , S eff , ρ c , the ratio of Si–H content and the I–V parameters were investigated. • Cells with the light soaking processes exhibited the efficiency gain of 0.87 %. • A industrial-grade efficiency >25.8 % of cells treated with optimized light soaking process. [ABSTRACT FROM AUTHOR]

Abstract: Ir–Zr co-deposition coatings with 71at% Zr were deposited on graphite by double glow plasma at 1073–1123K. The structure and composition of the coatings were confirmed by FE-SEM, XRD, XPS and EDS. The hardness and the elastic modulus of the coatings were estimated by nanoindentation instrument. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. The results showed that the coating was composed of nanocrystalline grains with a size of 80–90nm compared with 0.5μm for the pure Ir coating. The fine grains of the coatings might be attributed to the additional Zr element. New phases IrZr and ZrC were formed due to the high content of Zr and high deposition temperature. The hardness and elastic modulus of the coatings were about 7.5GPa and 388GPa, respectively. The adhesive force between the coating and the substrate was about 10N. [Copyright &y& Elsevier]

Abstract: Ir–Zr gradient coating was obtained on the Mo substrate by double glow plasma. The structure and composition of the coatings were confirmed by SEM, AFM, XRD and EDS, respectively. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. Compared with preferential growth orientation of (220) crystal plane of Ir coating, the Ir–Zr coating had a random orientation structure. The RMS roughness value of the Ir–Zr coating is 19.3nm, which was lower than the roughness value of 45nm for Ir coating. The Ir–Zr coating with the thickness of 5.0μm was composed of two distinct layers. The proportion of Ir decreased gradually from the surface of the coating to the coating/substrate interface. The Zr distribution decreased slightly in the coating. The adhesive force of the Ir–Zr coating was 15N. [Copyright &y& Elsevier]

• Alkaline water splitting requires improved catalysts for the hydrogen evolution. • Electrochemical production route for nanoscale iridium-nickel catalyst. • Oxalic acid as complexing agent for galvanic process. • Alloy-composition from 6 to 70% iridium, with best catalytic results for 70% Ir. In this study, iridium- nickel- catalysts were galvanostatically prepared from different iridium salts. The influence of deposition parameters and bath composition on surface morphology, alloy composition and catalytic properties for the hydrogen evolution reaction was determined. Oxalic acid was determined as complexing agent and improved the iridium incorporation rate and efficiency. The achieved alloy compositions ranged from 6% to 70% iridium, with best results for the hydrogen evolution reaction (HER) coming from an electrode with 70% iridium. [ABSTRACT FROM AUTHOR]

• Structure and HER performance of ED and DGP Ir electrocatalysts were studied. • ED Ir catalyst exhibited a superior electrocatalytic activity, with a low Tafel slope of 34 mV·dec-1. • The electrocatalytic activities were in order of ED Ir > DGP Ir > ablation Ir catalysts. Iridium (Ir), with low overpotential and excellent stability, is a promising catalyst for the hydrogen evolution reaction (HER) in alkaline electrolyte. Structure and HER performance of Ir electrocatalysts fabricated by electrodeposition (ED) and double glow plasma (DGP) were investigated. ED Ir nano electrocatalyst with rough surface was not completely covered and consisted of a mixture of nanocrystalline and amorphous. Homogeneous and dense DGP Ir electrocatalyst with micro-size was composed of many coarse particles. After ablation, the Ir grains coarsened, and many holes were formed. Boasting a large electroactive surface area and high electrical conductivity, ED Ir electrocatalysts exhibited a superior electrocatalytic activity in 1.0 M KOH solution, requiring only 0.044 V overpotential to obtain a current density of 10 mA·cm−2, with a low Tafel slope of 34 mV·dec-1 and a high exchange current density of 0.669 mA·cm−2, compared with DGP Ir electrocatalysts with and without high-temperature treatment. The electrocatalytic activities of the electrocatalysts were in order of ED Ir > DGP Ir > ablation Ir electrocatalysts. [ABSTRACT FROM AUTHOR]

• A novel ultrasound-assisted route was used for size control synthesis of PDA nanoparticles. • Nucleation and growth of PDA nanoparticles prepared with ultrasound were studied. • Effect of reaction conditions on size of PDA nanoparticle was investigated. The particle size is of importance for polydopamine (PDA) nanoparticles in different applications. Therefore, the synthesis approaches of PDA nanoparticles with fine-controlled size are highly desirable. Here, a novel ultrasound-assisted strategy for size control preparation of PDA nanoparticles was reported. The incorporation of ultrasound facilitated the reaction kinetics of DA, which increased the nucleation rate of PDA nanoparticles, therefore yielding smaller PDA nanoparticles. The diameter of PDA nanoparticles can be regulated effectively from 162.8 to 666.7 nm through adjusting dopamine (DA) concentration from 1 to 4 mg/mL in ultrasound-assisted route. This work has enriched the controllable synthesis methods of PDA nanoparticles, which opens more room for size dependent applications of PDA nanoparticles. [ABSTRACT FROM AUTHOR]

Improving the conversion efficiency of n-TOPCon solar cell is still a hot topic. The selective poly-Si based passivating contacts (Poly-SEs) are ideal candidates for reducing the parasitic absorption and contact resistivity of n-type silicon solar cells and for providing better current collection. In this work, we used LPCVD and the POCl 3 tube furnace diffusion methods to fabricate the selective poly-Si based passivating contacts, and studied the influences of key process parameters of the SiO x layer formation process (the oxidation duration (t oxidation) and the constant pressure duration (t pressure)), and POCl 3 tube diffusion process parameters (the POCl 3 -N 2 carrier gas flow rate at the deposition, deposition temperature, drive-in temperature) on the n+-poly-Si profiles, recombination current density (J 0), contact resistivity (ρ c) of n-TOPCon solar cells. The results showed that the t oxidation and t pressure had a significant impact on J 0 and ρ c which were mainly related to the distribution number of O and Si4+ content on the growth of the SiO x layer. And the influence of the drive-in temperature of phosphorus (P) diffusion process on J 0 value is stronger than that of the deposition temperature, which was mainly related to the chemical passivation of SiO x layer induced by P-indiffusion into Si at high temperature. The reduction in the thickness of poly-Si from 110 nm to 30 nm led to an increase in the short-circuit current density (J sc) per nanometer of ∼0.0093 mA/cm2 per nm. The Poly-SEs were fabricated by 3D printing mask technology and secondary LPCVD/phosphorus diffusion with J 0, n+ ≈ 5 fA/cm2 (n+-poly-Si layer ≈ 50 nm) and J 0, metal,n++ ≈ 73.8 fA/cm2 (n++-poly-Si layer ≈ 110 nm), and the efficiency was improved by 0.12% owing to the increase in J sc value of 0.28 mA/cm2. After optimizing the passivation process, the industrial-grade TOPCon bifacial cells reached an efficiency (E ff), V oc , J sc , and FF values as high as 25.4%, 721 mV, 42.2 mA/cm2, and 83.5%, respectively. • The SiO x /n+-poly-Si layer induced parasitic absorption encountered in n-TOPCon solar cells. • Selective poly-Si based passivating contacts formed by 3D printing mask technology and secondary LPCVD/phosphorus diffusion. • The key process parameters of the SiO x layer and n+-poly-Si layers were investigated. • Cells with J 0, n+ ≈5 fA/cm2 (50 nm) and J o, metal,n++ ≈73.8 fA/cm2 (110 nm) exhibited the efficiency gain of 0.12%. • A pilot efficiency >25.4% of cells treated with optimized passivation process. [ABSTRACT FROM AUTHOR]