Ir coating prepared on Mo substrate by double glow plasma

Dense and adherent Ir coating was obtained on the surface of the Mo substrate by double glow plasma, which had a deposition chamber and two cathodes. Argon gas was used as the working gas. The bias voltage of Ir target and Mo substrate were −800 and −300 V, respectively. The chamber pressure was 35 Pa. Microstructure of the Ir coating was observed by scanning electron microscopy. The Ir coating had a polycrystalline structure with preferential growth orientation of (220) crystal plane. The deposition rate was ~3.5 μm/h. The good adhesion resulted from the buffer layer between the Mo substrate and the Ir coating. The buffer layer, a combined Ir and Mo, was formed at the beginning of the deposition. The Mo concentration distributed gradiently along the depth of the buffer layer.