Preparation and Characterization of Ir Coating on Mo Network with a W Bond-Coat

Abstract:

A bi-layered Ir/W metallic coating was successfully deposited onto the Mo network via the magnetron sputtering method. The sputtering W bond-coat was proved able to enhance the binding energy between the sputtering Ir coating and the Mo substrate, and virtually neither delamination nor peeling off was observed for the as-prepared coating. In addition, the interdiffusion between the W bond-coat and the Ir coating or the Mo substrate was not apparent. The dense and adherent Ir coating was identified to have a polycrystalline structure with (111) orientation. According to the three zone model suggested by Movchan and Demchishin for sputtering metallic coatings, the microstructure of the bi-layered metallic coating was consistent with the Zone 1 features. In fact, the bi-layered coating had very low lateral strength and inclined to crack under tension.

Key words:magnetron sputtering; Ir coating; W bond-coat; preferred growth; microstructure