Effects of ion beam mixing of silicon carbide film deposited onto metallic materials for application to nuclear hydrogen production

The effects of ion beam mixing of the SiC film coated on metallic substrates were studied, aiming at developing highly sustainable materials at above 1173 K in SO3/SO2 ambience. Firstly, ∼50 nm thick SiC films were deposited by e-beam evaporative method on stainless 316 L, Inconel 800H, Inconel 690, and Hastelloy-X substrates, followed by the 100 keV (Ar and N) ions bombardment to mix the interfacial region. After ion beam mixing, additional ∼500 nm thick SiC film was deposited onto the ion bombarded SiC film. Samples with and without ion beam mixing were immersed in 50% H2SO4 solution for 1 h with heating the solution up at 573 K. The film in the as-deposited sample was completely removed during the immersion, while the ion beam mixed sample exhibited no detachment of the deposited film. The corrosion of non-ion beam-mixed sample initiated from non-deposited metallic surface and then propagated to the film deposited region, flaking-off the film from the edge. The interface formed by ion beam mixing seems to be protective against the corrosion. The SiC film/metallic substrates were heated up to 1223 K. The film deposited on the stainless steel substrate was completely peeled off, while the films deposited on Ni-based alloys all sustained. This is due to the difference of thermal stresses between the film and substrate materials. The best materials combination in our experimental scheme is the SiC film and the Hastelloy-X, because their thermal properties are more similar than for the other materials combinations.