Corrosion resistance of ceramic-coated stainless steel in a Br 2O 2Ar atmosphere

Abstract

Coatings of SiC TiC compositional graded film (FGM), m-HfO 2 and c-HfO 2 films on stainless steel (SUS304) plates have been investigated as candidate materials for ‘UT-3’ which is an effective process of hydrogen production through thermochemical decomposition of water. Changing the source gas concentration leads to composition control in TiC-SiC composite films. Cracks in the films could not be avoided in either the TiC-coated SUS304 nor the SiC-TiC double layer-coated SUS304. However the SiC TiC FGM-coated SUS304 had no cracks. Corrosion of the TiC and SiC-20 mol%TiC double-layer-coated SUS304 in the Br 2-O 2-Ar atmosphere was mainly caused by oxidation of the TiC film and SUS304. The SiC TiC FGM-coated SUS304 showed superior corrosion resistance in isothermal and cyclic heating conditions. m-HfO 2 and c-HfO 2 (7·1–44·5 mol% Y 2O 3) were attained by the changing of Y(DPM) 3 gas concentration. XRD measurement shows the monoclinic and cubic HfO 2. Both plate-like and columnar texture in the m-HfO 2 and c-HfO 2 films were observed. m-HfO 2, in which columnar texture, coated SUS304 showed the excellent corrosion resistance in Br 2O 2Ar atmosphere under heat cyclic conditions. This is thought to be due to the effects of columnar texture on the thermal stress relaxation, and of the excellent corrosion resistance of the m-HfO 2.