Morphology and mechanical characteristics of monolayer and multilayer Ir coating by double glow plasma

Multilayer iridium coating was manufactured on tungsten carbide substrates by a double glow plasma process. As comparison, monolayer was also produced. The microstructure and morphology were observed using scanning electron microscopy. Grain orientation and phase were determined using X-ray diffraction. The residual stress of the coating was studied by glancing incidence X-ray diffraction. The adhesive force of the coating was measured by a scratch tester. The results showed that both monolayer and multilayer had a polycrystalline phase with a strong (110) reflection. The coating had an excellent adhesion with no evidence of delamination. The adhesive force of the monolayer and multilayer was about 50 and 43 N, respectively. The interfacial reaction between the substrate and the layer occurred and a new WIr phase was found due to the high-temperature deposition process. The residual stress in the monolayer and multilayer was -1.6 and -1.1 GPa, respectively.