Method for thermal spray coating and rare earth oxide powder used therefor

摘要

The invention discloses an efficient method for the formation of a highly corrosion- or etching-resistant thermal spray coating layer of a rare earth oxide or rare earth-based composite oxide by a process of plasma thermal spray method by using a unique thermal spray powder consisting of granules of the oxide. The thermal spray granules are characterized by a specified average particle diameter of 5 to 80 mu m with a specified dispersion index of 0.1 to 0.7 and a specified BET specific surface area of 1 to 5 m<2>/g as well as a very low content of impurity iron not exceeding 5 ppm by weight as oxide. The flame spat powder used here is characterized by several other granulometric parameters including globular particle configuration, particle diameter D90, bulk density and cumulative pore volume.