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In order to solve the serious oxidation problem of the iron-based amorphous coating by arc spraying, the iron-based amorphous coating was prepared on the 20NiCrMo substrate by plasma transfer arc wire spraying(PTWS), and the parameter optimization experiment of four-factor three-level process was designed by the response surface method, and the mathematical model relationship between argon flow, hydrogen flow, working current, spraying distance and porosity was established. Then, the iron-based amorphous coating was prepared by using the optimal process parameters, and the surface, cross-sectional morphology, phase composition and hardness of the iron-based amorphous coating were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and HV-1000A. The polarization properties of coating and substrate was tested by IM6ex type electrochemical workstation. The results show that the porosity of the coating will decrease with either the increase in argon gas and the decrease in spraying distance, or the decrease in argon gas and the increase in spraying distance, when the working current is constant. Under the optimal process parameters, QAr=115 L/min, QH2=4 L/min, I=300 A, D=150 mm, d=12 mm, Vwire=60 mm/s, the porosity of the obtained iron-based amorphous coating is 2.14%, the average hardness is 960HV0.1, the corrosion potential is -0.4841 V and the corrosion current was 3.716×10-5 A·cm-2, which indicate the coating has excellent corrosion resistance properties.

In order to further improve the coating microstructure and properties，a new surface micro-crystallization technique，high temperature assisted ultrasonic deep rolling (HT+UDR)， was used to treat the cermet coating， which could soften the cermet coating by high temperature treatment， thus reducing the strength and hardness of the coating，and large plastic deformation would occur on the coating surface during ultrasonic deep rolling. In this paper， SEM， EDS， hardness test and XRD were used to investigate the effect of different pressing amounts (0.20 mm，0.25 mm，0.30 mm) in high temperature assisted ultrasonic deep rolling on the microstructure，structure and properties of ceramic coating on 45 steel substrate. Results showed that after HT+UDR+0.25 mm treatment， the longitudinal cracks in the coating were closed or transformed into transverse cracks under the action of plastic flow， and the porosity was small. After work hardening and grain refinement， the surface hardness was further increased to 650.2 HV. The residual tensile stress on the coating surface was changed into residual compressive stress，with the maximum value of -337.9 Mpa. However， cracks appeared on the surface layer of the coating after HT+UDR+0.30 mm treatment， and the dynamic recrystallization behavior of the surface was intensified. The decrease of dislocation density led to the release of residual stress， which was 8.67%lower than that of HT+UDR+0.25 mm treatment.

This study aimed to address the thermal degradation of resin‐based friction materials in the mid‐temperature stage (200–250°C), as well as the resulting instability of the friction coefficient and decrease in the mechanical properties. To investigate the impact on the toughening and wear resistance properties, this study employed nanosilica‐modified resin‐based friction materials. The mechanical, friction, and wear properties of the modified samples were tested using a Rockwell hardness tester, hydraulic universal testing machine, and constant speed friction tester. The phase composition and microstructure of the samples were analyzed by scanning electron microscope, energy‐dispersive x‐ray spectroscopy, x‐ray diffraction. When the mass fraction of nanosilica was 3%, modified sample S3 exhibited excellent mechanical properties, with shear strength and compressive strength reaching 40.3 and 171.7 MPa, respectively, which were increased by 30% and 9% compared to unmodified sample S1. Moreover, the density and hardness of sample S3 showed minimal variation compared to those of unmodified sample S1. In the temperature range of 100–250°C, the wear rate of modified sample S3 remained within the range of 0.22 × 10−7–0.38 × 10−7 N−1 m−1, with a friction coefficient of 0.38 at 200°C, demonstrating excellent wear resistance. [ABSTRACT FROM AUTHOR]

Due to its adverse environmental and human health hazards, addressing the elimination of nitric oxide (NO) has become a pressing concern for modern society. Currently, electrochemical NO reduction provides a new alternative to traditional selective catalytic reduction technology under mild reaction conditions. However, the complexity and variability of products make the coverage of NO an influencing factor that needs to be investigated. Hence, this study delves into the coverage-sensitive mechanism of electrochemical NO reduction on cost-effective perovskite catalysts, using SrTiO3 as an example, through density functional theory calculations. Phase diagrams analysis reveals that the coverage range from 0.25 to 1.00 monolayer (ML) coverage is favorable for NO adsorption. Gibbs free energy results indicate that the selectivity is significantly influenced by NO coverage. NH3 is likely to be generated at low coverage, while N2O and N2 are more likely to be produced at high coverage through a dimer mechanism. Charge analysis suggests that the charge transfer and Ti–O bond strength between reactants and catalysts are crucial factors. This work not only provides deep insights into coverage-sensitive reaction mechanisms but also is a guideline towards further rational design of high-performance perovskite catalysts. [ABSTRACT FROM AUTHOR]

The present paper presents a numerical approach to investigate the surface layer residual stress after ultrasonic surface rolling process（USRP）,which is a severe plastic deformation process involving complex static extrusion and dynamic impact.According to the technological principle of USRP developed finite element model,assessment of meshing accuracy as well as definition of loading condition.As supplied 304 Austenitic Stainless Steel disc was subjected to ultrasonic surface rolling for validation of FEM,then simulates the processing of ultrasonic surface rolling,analysis of the residual stress field distribution characteristics and the influence of processing parameters on the rule.From the simulation results it can be seen that the surface of the material has a uniform distribution of residual compressive stress,with the increase of depth,the residual stress has a compressive stress peak and a smaller peak of the tensile stress and finally reduced to 0.The influence of machining parameters on the magnitude and depth of residual stress is different,the static pressure,the coverage rate and the number of processing have great influence on the amplitude and the amplitude is small.

In this paper, 1045 steel is joined to Q235 steel using continuous drive friction welding. The temperature distribution and material flow during the welding process were analyzed by numerical simulation and the flow behavior was further explained by grain distribution. The microstructure and mechanical properties of the joint were investigated experimentally. The results show that with the increase of friction time, the joint temperature first increases and remains in dynamic equilibrium. The joints were divided into a central region, a 0.5R region, and an edge region along the radial direction. The highest temperature of the joint first appears in the edge region, with a relatively low temperature in the central region. The material flow rate in the edge region is faster than that in the center and 0.5 R regions, and the maximum material flow rate increases and then decreases with increasing friction time. When the friction time is suitable, the heat distribution is uniform and sufficient, and the grains show a better refinement effect, which is beneficial to the improvement of the mechanical properties of the joint. Due to the grain refinement of the joint, the highest microhardness is obtained at the weld zone in all welding conditions. All joints fractured on the Q235 steel base material side, and the fracture form was ductile fracture. [ABSTRACT FROM AUTHOR]

Abstract: In order to research tribological properties of texturing coating and get the best formulation and moulding of preparing surface textured lubricant anti-wearing coating, in this paper, the tribological orthogonal test which is about lubrication phase and surface micro moulding of coating is carried out, under different temperatures, analysis of variance is also carried out for friction coefficient and wear rate, getting a better level combination of every factor, then by synthetically analyzing the tribological properties, the level combination of the better friction coefficient is formulation 1(lubricant WS2: content of 30%) and its moulding(surface texture: pit trench). The level combination of the better wear rate is formulation 2(lubricant WS2: content of 20%) and its moulding(surface texture: diamond texture). To the two formulations and their mouldings, according to the test and analysis, the abrasion loss is low, so it isn’t considered for different components’ influence on wear, but it is mainly considered different components have an effect on friction coefficient. The best formulation and moulding are got: formulation 1(lubricant WS2: content of 30%) and its moulding(surface texture: pit trench). [Copyright &y& Elsevier]

Due to its adverse environmental and human health hazards, addressing the elimination of nitric oxide (NO) has become a pressing concern for modern society. Currently, electrochemical NO reduction provides a new alternative to traditional selective catalytic reduction technology under mild reaction conditions. However, the complexity and variability of products make the coverage of NO an influencing factor that needs to be investigated. Hence, this study delves into the coverage-sensitive mechanism of electrochemical NO reduction on cost-effective perovskite catalysts, using SrTiO 3 as an example, through density functional theory calculations. Phase diagrams analysis reveals that the coverage range from 0.25 to 1.00 monolayer (ML) coverage is favorable for NO adsorption. Gibbs free energy results indicate that the selectivity is significantly influenced by NO coverage. NH 3 is likely to be generated at low coverage, while N 2 O and N 2 are more likely to be produced at high coverage through a dimer mechanism. Charge analysis suggests that the charge transfer and Ti-O bond strength between reactants and catalysts are crucial factors. This work not only provides deep insights into coverage-sensitive reaction mechanisms but also is a guideline towards further rational design of high-performance perovskite catalysts.

The application of covalent organic frameworks (COFs) for the photocatalytic reduction of CO 2 is mostly limited by severe charge recombination and low sunlight utilization. Herein, a triazine-based COF with an electron-rich and large π-conjugated system (TCOF) was employed as a building block and integrated with CuInS 2 (CIS) to construct a noble-metal-free and high-efficiency photocatalyst for CO 2 reduction. The in situ growth of CIS nanosheets on TCOF creates a p - n heterojunction, named CIS@TCOF. Compared with TCOF, the CIS@TCOF heterostructure exhibits a dramatically boosted photocatalytic performance in the reduction of CO 2 . The produced HCOOH yield over 10 wt % CIS@TCOF can be up to 171.2 μmol g -1 h -1 under visible light irradiation with good reproducibility, which is about 3 times as high as that over TCOF. Further in-depth studies indicate that the introduction of CIS not only enhances the visible light utilization but also restrains the recombination of photogenerated electron-hole pairs efficiently and facilitates the photoinduced charge transfer via the p - n heterojunction system due to the unique structural and compositional features. This research shows the great potential of COFs as efficient photocatalytic carbon fixation materials and provides a versatile route to construct semiconductor-COF heterostructures for photocatalysis.