Papers by Author: Ye Sheng Zhong

Abstract: Microarc oxidation (MAO) is a relatively convenient and effective technique to deposit ceramic coatings on the surfaces of Al, Ti, Mg and their alloys. This technique can introduce various desired elements into titania-based coatings and produce various functional coatings with a porous structure. Microarc oxidized (MAO) TiO2-based coatings on titanium alloy were formed in electrolytes containing aluminate and ZrO2 particles. The phase composition of the samples was analyzed by glance-angle X-ray diffraction and the surface morphologies of the samples were observed by a scanning electron microscopy (SEM). In addition, the element concentrations on the surfaces of the samples were measured by an energy dispersive X-ray spectrometer. The experiment results indicated that: MAO coatings, which are porous structures and exhibit good interfacial bonding to the substrate, may possess specific surface structures such as crystal phase, non-equilibrium solid and complex mixed-compounds since complex plasma physical and chemical reactions.

Abstract: Ti3SiC2 is one of the nano-layered ternary ceramics Mn+1AXn, where M is a transition metal, A is an A-group (mostly IIIA or IVA) element, and X is C or N. With the filler of Ag-Cu-Ti, the brazing of Ti3SiC2 has been conducted at 800°C–950°C for 5-10min under 3.5×103Pa in a vacuum. The phase composition and microstructure of the joints were investigated by XRD, SEM AND EPMA. The diffusion of Cu element in fillers through the reaction zone toward Ti3SiC2 is the main controlling step in the bonding process. Joint strengths were evaluated by three point bending test. The maximum flexural strength of joints reaches is 306±11MPa, which is lower than the bending strength of Ti3SiC2, obtained under the same condition.

Abstract: The preparation technologies of thermal barrier coating by the Electron Beam Physical Vapor Deposition (EBPVD) technique were briefly introduced in this paper. And design principal of thermal barrier coating is discussed, at the same time the selection of raw material was also taken into account. On the basis of several assumed perfect conditions, a reasonable Finite Element Analysis (FEA) physical model was built up in order to exactly describe the whole deposition process. Taking the advantage of the large-scale commercial software of FEA, the distribution of residual stress and the possible displacement tendency were obtained. The analysis results show that: with the increasing substrate preheating temperature, the inter-laminar shear stress increases but the axial residual stress decreases. And the probability of cracking after de-bonding tends to enhance as the thickness of deposition coating is increased. Also it is verified that the FE model has produced little numerical error.