Applied Mechanics and Materials Vols. 217-219

Abstract: The performing features of workpiece cathode (W electrode) and the orificed hollow cathode (P electrode) in the triple-cathode plasma surface alloying system are studied. Current densities of the W cathode and the P cathode are obtained under the conditions of the different voltages and the different chamber pressures, based on which current transmitting densities of the orifice of the P cathode are obtained and the conditions of plasma plume flow occurrences are, combined with the observe records of experiments, discussed and analyzed.

Abstract: A CFD numerical model has been established to study the growth of cadmium telluride (CdTe) on substrate using metalorganic chemical vapour deposition technique in atmospheric pressure (AP-MOCVD) and hydrodynamics in an inline MOCVD reactor. The numerical simulations have been conducted using the CFD code – ANSYS Fluent. Dimethylcadmium (DMCd) and diisopropyltelluride (DIPTe) have been employed as precursors while H2 is acting as the carrier gas. In order to assess the effect of various conditions on CdTe film growth and uniformity, heat transfer and mass transport behaviours of the chemical species in the reactor have been fully investigated. In addition, material utilization and fluid dynamics in the reactor are also discussed.

Abstract: In order to improve the anti-wear and anti-corrosion properties of mechanical parts used in high temperature friction conditions, the Ni-W alloy brush plating coatings were prepared and their tribological properties at elevated environment temperatures were investigated. The results show that the friction coefficients of Ni-W/GCr15 tribo-couples are in the range of 0.168～1.048, which take on the decreasing trend as the increase of environment temperatures. The wear losses of the coatings increase at elevated temperatures, and the critical temperature in which the coatings produce serious wear from slight wear is 250°C. The wear mechanism of the coatings are micro-cutting at room temperature, then it changes into adhesive wear accompanied by a certain of delamination when temperature is high than 250°C. When temperature is higher than 400°C, the main wear mechanism of the coatings is adhesive wear and delamination.

Abstract: In order to research the technique of reaction nitrogen arc cladding, the 5 factors 4 levels orthogonal experiments have been designed, and the effects of process parameters (such as cladding current, tungsten polar diameter, nitrogen flow, cladding speed and precoated thickness) on coating wear resistance performance were discussed. The process parameters were optimized as follows: cladding current 200 A, tungsten polar diameter 1.6 mm, nitrogen flow 12L. min^-1, cladding speed 2 mm.s^-1, precoated thickness 1.5 mm.

Abstract: Particle reinforce composites coating of TiAl(CN) was made on the surface of Q235B steel substrate by reaction nitrogen arc welding cladding process, which take the titanium powder, aluminum powder and the graphite powder as original material. The microstructures, structure and the phase of the coatings were investigated by scanning electronic microscope, X-ray diffract instrument, micro-hardness, reciprocating friction testing machine. The result indicated that the TiAl(CN) coating has a metallurgy union with the substrate, the phase of the coatings are mainly composed of TiAl(C _0.51 N _0.12), AlFe3 and FeC. The microhardness and anti-abrasive performance of the TiAl(CN) coating is better than the Ti(CN) coating processed by tungsten nitrogen arc surfacing welding process.

Abstract: The paper states the components of transfer roll coater for lithium-ion electrodes and the working principles of it.The high-precision coater with a unwinding unit, a coating unit, a drying unit, a leading unit and a rewinding unit has been developed. The methods which are focused on the manufacture precision, installation precision and control precision of the coating head to achieve higher coating accuracy were explored.

Abstract: Conditions of tool wear can be indirectly reflected by the texture features of the machined image due to the direct contact between the work piece and tool in cutting process. In this paper, a new texture analysis method is proposed based on the Hough transform and Run length statistics. In order to remove non uniform illumination and noise, the original machined images are preprocessed by contrast enhancement algorithm and adjacent region average method, and then the edge images are obtained by a canny edge detector. Hough transform is then applied to the edge images to detect all line segments. The length characteristics of line segments are detected by using Run length statistics method. The average length and angle characteristics of edge images are used to determine the tool wear. Through our experiments, we found a high degree of correlation between texture features of machined images and tool wear. The combination of Hough transform and Run length statistics method improve the monitoring performance.

Abstract: The copper infiltrated stainless steel was formed by double glow plasma surface metallurgy technology on 0Cr18Ni9 steel. A comparative test with untreated samples was carried out. The results indicates that the friction coefficient decreases with the load increasing, and copper infiltrated stainless steel is superior to untreated samples in wear rate and wear resistance, finally makes an analysis of the reasons.

Abstract: Using micro-arc oxidation technology in preparation Ti6Al4V alloy surface oxidation film, adding to the electrolyte H2O2, influence of H2O2 addition amount of oxidation film characteristics has been studied. The results show that, H2O2 addition amount of 4.0 g·L-1, positive critical arcs voltage minimum, for 338 V. SEM analysis showed that, electrolyte of H2O2 addition amount by 1.0 g·L-1 increased to 4.0 g·L-1, film hole diameter after decreasing, micro-arc oxidation film layer of density increases. Oxidation film surface roughness reduced to 7.619 when H2O2 addition amount for 4 g·L-1. With H2O2 addition amount from 1.0 g·L-1 increased to 4.0 g·L-1, micro-arc oxidation film in the wear process mass loss is reduced, wear resistance for promotion.

Abstract: TiN coating is often coated on fine blanking tools made of with the powder metallurgy high speed steel S790 by Multi-arc ion plating. The phase variation, residual stress and microhardness of TiN coatings were respectively analyzed by X-Ray Diffraction(XRD) and Vickers hardness tester in this research. The result shows that: there is obvious preferred orientation in the crystal surface (1 1 1) and (2 2 2) of TiN coating, the residual stress of TiN coating ranges from -2 347 MPa to -1 920 MPa, and that of the substrate from -154.9 MPa to -69.21 MPa, both of which decrease with the increasing of coating thickness. The TiN coating on the S790 substrate was annealed at temperature 500°C for one hour. It was revealed that the stress state of TiN coating was better and thus the properties of the TiN coating were improved.