Advanced Materials Research Vols. 538-541

Abstract: This paper studies the formation of boride layers on substrate injector combustion AISI 304 per nozzle surface treatment in addition the formation of hard layers and FeB type Fe2B were obtained in a temperature range of 1223 and 1273 K with exposure times of 1/2, 1, 3 and 5 h. The study consisted boride type layer formed on the surface and the characterization of the boride layer were evaluated by the method by analysis of X-ray diffraction (XRD), the distribution of the alloying elements were detected by spectrometry energy Dispersive (EDS) inside the surface, the evaluation of adhesion of the layers was determined by the technique Rockwell-C hardness was also evaluated and the Young's modulus of the layer by the nanoindentation technique with the load of 200 mN. Finally this study hardening fuel injector; is desired increase its useful life.

Abstract: AZ31 magnesium alloy preset SiC-316L powder by laser alloying on the surface treatment. The organizational structure and composition of alloying layer material by XRD, SEM and EDS phase were analyzed. The results show that the alloying layer surface has roughness, lap in good condition, no pilling, pores and cracks defect, etc. Alloying layer is mainly composed of the original phase Mg, Fe, SiC and the oxides of MgO and SiO2. The columnar grain zone perpendicular to the interface and pointing to the alloyed layer. It is formed in the bottom of the alloyed layer and the interface zone of magnesium alloy substrate.

Abstract: Wear-resistant casting was made by V-EPC infiltration process. This paper puts forward and analyses the mechanical properties and forming mechanism of the layer. The matrix material was high boron steel casting. By partial casting alloyed, the surface composite materials layer was ceramic particles, such as WC, Ferrochromium, and Borax, etc. High boron molten metal was infiltrated into the composite layer and a good cast-infiltration layer may be formed by the interaction of vacuum and high temperature. The test result shows that using this process we can get the casting surface which is special abrasion-resistance with the remarkable characteristics such as simple process and low cost. It is a new process that wear-resistant casting will be made of.

Abstract: In this paper, the ZnO nano powders were prepared by sol-gel method and modified with diphenyl-methane-diisocyanate (MDI). The modified ZnO nano powders can disperse in acrylic polyurethane coating homogenously. The dispersion stabilization of modified ZnO nano powders in acrylic polyurethane coating was significantly improved in comparison with the native ZnO nano powders, which was due to the introduction of grafted polymers by surface treatment. The ultraviolet absorption ability of ZnO nano powders were tested by UV spectrophotometer, when the modified ZnO nano powders are added into the acrylic polyurethane coating. The addition amount of ZnO powders is more; the ultraviolet absorption ability is stronger.

Abstract: The influence of curved surface on the method of polychromatic speckle autocorrelation measuring surface roughness is studied by introducing the curvature radius of surface. The rough surface, and the dichromatic speckle patterns, and trichromatic speckle patterns are simulated, and the effects of different radius of curved surface on speckle patterns and speckle elongation ratio are discussed. The results show that the larger curvature radius is, the larger speckle elongation becomes, and the smaller the deviation of measured surface roughness is. Therefore, influence of curvature of rough surface on measurement precision should be taken into consideration during measuring process.

Abstract: In this study, conventional and nanostructured MCrAlY/ZrO₂-7wt.%Y₂O₃ double-layer thermal barrier coatings (TBCs) were fabricated on TiAl base intermetallic alloy substrates by the plasma spraying technique. The microstructural characterization and thermal insulation capability of the two types of coatings were comparatively researched. The results show that the conventional ceramic coating has a typical lamellar stacking characteristic. However, the nanostructured coating exhibits a bimodal microstructure, which is composed of both fully melted regions and partially melted regions (remained nanoparticles). The nanostructured TBCs has higher thermal barrier effect than the traditional one. The temperature drops of the nanostructured TBCs at 1100 °C increases 53% compared with that of the conventional TBCs.

Abstract: A three-dimensional contact model was established between two isotropic rough surfaces exhibiting fractal behavior,and the equivalent plastic strain was discussed using the finite element analysis. The maximum equivalent plastic strain and its depth are presented with the different paths of rough solid when loading. The result showed that the equivalent plastic strain versus different depth which at different locations showed different laws, in the top area of the asperities versus different depth, the maximum equivalent plastic strain occurs in the subsurface which range about 5 um from the surface. In addition, with different deformation characteristics, the degree of the equivalent plastic strain was different. The contact model between two rough solids will lay a foundation to further research on the substance of the process of friction and wear.

Abstract: Spinel LiMn₂O₄ is treated on its surface with CoO_1+x/ZrO₂ in this paper. Metal oxide-coated spinel LiMn₂O₄ was investigated with respect to electrochemical characteristics. The metal oxide coating process was carried out by using the solution method. CoO_1+x/ZrO₂-coated spinel LiMn₂O₄ exhibited stable cyclic performance in the range from 3.0 to 4.4V, and it has less electrochemical impedance, polarization and capacity loss. The cell composed of the CoO_1+x/ZrO₂-coated spinel LiMn₂O₄ can be discharged at a large current density.

Abstract: In this paper, the DZ4 Ni-based superalloy was irradiated by high intensity pulsed C ion and H ion beam. The parameters of ion beam were: accelerating voltage 250 kV, pulse duration 70 ns, ion current density 160 A/cm2. Irradiation pulses were 2, 5, 10 and 15. The morphology of DZ4 before and after irradiation was observed by scanning electron microscope (SEM). The phase structure and stress state were analyzed by X-ray diffraction (XRD). The results show that there were some craters on the surface of the sample after irradiation, as the irradiation time increased, the crater boundary became blurred and even disappeared. The surface tensile stress produced by initial irradiation could be relieved after several irradiations pulses. The corrosion resistance of irradiated DZ4 alloy was improved greatly. The continuous and dense α-Al2O3 layer that formed on irradiated DZ4 surface at 1000°C atmosphere increased the high temperature oxidation resistance.

Abstract: 708C Ball bearings were made of 9Cr18 steel which had precision of class 4, MoS2-Ti composite coatings were deposited on inner and outer races of ball bearings by unbalanced magnetron sputtering system, and bearing cages were made of PTFE-based self-lubricating polymers. Bearing’s tribological torques as a function of storage time in high humidity environment were studied by using LHU-2 thermal & humidity test chamber and Bearing 2000 torque measurement device. Developing bearing vacuum performance test rig to research bearing’s torque as a function of running time, bearings were dismantled after test and using XPS to analyze the surfaces of bearing’s races and balls. The results show that storied in the environment of 30°C, 85% RH, bearing’s running torques increased proportionally as the storage time went on. When run-in the bearings which were storied for 440 days, the start and average running torques of bearings could come back to the level which was the same as the test start, but the fluctuation of bearing’s average running torque increased. Running in one direction at the speed of 650 r/min, in vacuum environment (~10-4Pa) and ambient temperature, tested bearings showed good running performance with low friction torque varied only between 1g·cm~2 g·cm until to the test ended at 1.872×108 revolutions. XPS analysis showed that a stable and sustainable solid lubrication system was established among bearing’s races, balls and cages.