Thermal stability of iridium coating prepared by MOCVD

A multilayer Ir coating with equiaxed grains was prepared using metalorganic chemical vapor deposition on Nb substrates by thermal decomposition of Ir(acac)3 precursor. Thermal stability of the coating was investigated at 1200 °C and 1300 °C in Ar. The Ir coating exhibited different thermal stabilities depending on heating temperatures. After heat treatment, the prepared nanometer and sub-micrometer grains grow obviously and grain size increased with rising heating temperature. Pores diffused outward and their amount reduced. After heat treatment, the coating gradually transformed into a compact layer. Nb diffused into Ir coating during heat treatment, and solid solutions were formed at 1300 °C.