Preparation And Study Of Doping Nanoparticles Al₂O₃/TiO₂/β-Sialon Composite Coating

This paper deals with the preparation of thermally sprayable powders by spray-drying and sintering using nanometerTiO2, nanoAl2O3, and micron Al2O3, micro TiO2and micron beta Sialon as start materials, his study focuses on the heat treatment of the agglomerated Al2O3/TiO2/β-Sialon powder, and there search on the microstructure of the coating. During the experiment the powder's flow ability and apparent density after heat treatment at different temperatures is surveyed. The transformation process of the particle's shape at high heating temperatures is discussed.The deposition of Al2O3/TiO2/β-Sialon coating by plasma spraying. The influences of the process parameters on the structural morphologies and properties of the spray-dried and sintered powders were investigated. The structure of the as-sprayed Al2O3/TiO2/β-Sialon coating was characterized using XRD and SEM, and the mechanical properties and insulation performance were measured.The Al2O3/TiO2/β-Sialon coating is obtained on the stainless steel via Plasma spraying with nano-microns doping reunion body powder. In this research program scanning electron microscopy and X-ray diffraction are used to characterize the powder and the coating. When heating temperature up to1200℃the distinct sintering phenomenon happens in the agglomerated powder and nanocrystalline particle's size reach micron scale. Thus the temperature of heat treatment should be controlled under1200℃. After the reasonable heat treatment, the flow ability of the agglomerated powder is improved, apparent density enhanced, the nanocrystallines inside the agglomerated powder remained which are fit for thermal spraying. The free surface and the cross section of the coating are examined. It is revealed that the coating consists of nano/micro structure without notable laminar structure. A part of the coating is microstructured derived from melted agglomerated powder in plasma and another part is density structural organization from unmelted agglomerated powder.The insulation performance of the nano doping Al2O3/TiO2/β-Sialon coating is better than micron P7112and nano P7112coating. This is mainly decision by the composition and structure of composite coating. Study the insulation performance of the coating with the change of porosity. As coating porosity decreases, the insulation performance enhancement. But the change is not very obvious.