As a candidate material against plasma etching, yttrium oxide has been coated onto etching chamber by plasma spray technique. However, the plasma spray technique introduces undesirable coating properties such as porous structure and deleterious thermal effects. To reduce the disadvantage of thermal impact, cold spray was used as an alternative technology to deposit thick and dense yttrium oxide coatings. Primary nanoscale Y 2 O 3 were used as the original powder, for the ceramic materials are intrinsic brittle and are difficult to be deposited by cold spray. The nano-powder were first agglomerated by hydrothermal treatment with addition of inorganic salt to acquire suitable powder for cold spray, and then deposited on aluminum alloy 6061 substrates by cold spray process with compressed air as propellant gas. About 200μm yttrium oxide coatings were formed on the substrate alloy. Different processing parameters were employed to optimize microstructure and properties of the coating.

In this paper, we reported our investigation on preparing inorganic phosphate ceramic coatings on the surface of γ-TiAl based alloy by air spray. The high temperature performance of the coatings was tested by thermal shock test, cyclic oxidation and isothermal oxidation at 950 °C. The results showed that the coatings exhibited significant improvement on high temperature anti-oxidation performance of the base alloy. No obvious cracks or spalling of the coatings occurred after oxidation experiment under isothermal oxidation condition at 950 °C for 1000 h. The characterization was carried out to analyze the microstructure of the coatings before and after oxidation test.