Ir is the most interesting as an effective oxygen diffusion barrier for super high-temperature structural materials. In this study, an Ir coating, approximately 7 μm thick, was deposited onto Mo substrate by double glow plasma at substrate temperature of about 1,120 K in an argon atmosphere. The crystal orientation, morphology and mechanical property of the Ir coating were investigated by XRD, SEM, AFM, TEM, nanoindentation and scratch test. The results indicated that the (220)-oriented Ir coating was composed of the columnar grains. The surface roughness of the Ir coating was higher than that of the substrate. The hardness and the elastic modulus of the Ir coating were about 9.5 and 340 GPa, respectively. The coating had a high hardness due to the sub-micrometer size grains. The coating had good scratch resistance due to the strong adhesion of the coating to the substrate.
Coating Morphology Hardness Plasma discharge
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This work has been supported by the National Natural Science Foundation of China (50872055/E020703) and the fund of the State Key Laboratory of Solidification Processing in NWPU (SKLSP200907). The authors gratefully acknowledge Dr. Jun Huang for help in Nanoindentation experiment and for useful discussions. The authors would also like to thank Prof. Fengming Pan and Mr. Yan Zhu at College of Science for their help in AFM characterization.