Reparation Of Phosphat Coating And The Research Of Its Application

Inorganic heat resistant coating have been widely used in petroleum,petrochemical, steel, power and aviation and other industries in recently years forthe much more advantages, such as good adhesion strength, good performance athigher temperature et al. However, due to curing temperature of inorganic coating istoo high it limited further application of such coatings.In this paper, phosphate, magnesium oxide and aluminum hydroxide are themain raw material to optimize the preparation of inorganic adhesive. Based on thisresearch, a good adhesion, good corrosion resistance and high temperaturecapability of the aluminum-based high temperature coatings of inorganic phosphatewas prepared. Thermal analysis, scanning electron microscope (SEM), chemicalanalysis, electron probe are used to study the physical properties and high corrosionresistance of the coating.TiAl alloys for the aerospace industry have a broad application prospectsthrough the development of a new type of inorganic phosphate ceramic coating athigh-temperature to further improve the high temperature oxidation resistance of thealloy.In this thesis, ceramic aggregate is added into phosphate binder to forminorganic phosphate ceramic coating at high temperature. Inorganic heat resistantcoatings on TiAl alloy substrate was sprayed using pneumatic spray method andthen to study the structure and high temperature coatings oxidation.After spraying on the TiAl alloy substrate, the cured coating surface is smooth,uniform, dense, non-porous and cracks and other defects, and then well bonded tothe substrate. The coating does not damage and fall off the substrate after thermalfatigue experiment for25cyclic test, indicating that the coating has a good thermalfatigue stability.After110cyclic oxidation tested at950℃and1100h isothermal oxidationexperiments at950℃, the specimen shows a great improvement in oxidationresistance and the growth of oxidation weight is smaller than the TiAl matrix. Theoxides in the coating are mainly Al2O3and SiO2. The microstructure analysis showsthat there is a continuous compact black Al2O3layer on the matrix. No oxygenelement could be detected in the TiAl substrate. It shows that O elements effectivelyblock the diffusion to the substrate. It shows that the inorganic phosphate ceramic coating at high temperature indeed improve oxidation resistance TiAl matrix.