Role of chemical composition of oxide layer on stainless steel for ZrO₂ coating by hydrothermal process

Thin films of ZrO₂ have been developed by hydrothermal process on pre-oxidized stainless steel (SS) surfaces composed of different oxides like spinels or α-Fe₂O₃. Variations in thicknesses and uniformity of ZrO₂ films have been observed on different pre-oxidized SS surfaces. Raman scattering spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction techniques have been used to explain mechanisms of formation of ZrO₂ films on various pre-oxidized SS surfaces. A pre-oxidized layer of α-Fe₂O₃ seems to be an ideal oxide on the SS surface for uniform coating of ZrO₂. This may be attributed to close match of lattice parameters of ZrO₂ with that of α-Fe₂O₃. - Highlights: • Developed tetragonal ZrO₂ films on stainless steel (SS) by hydrothermal process. • α-Fe₂O₃ on SS is prerequisite for uniformly thick and crystalline ZrO₂ coatings. • Spinels and α-Fe_2−xCr_xO₃ on SS result in thin and non-uniform ZrO₂ coating