ZrO2 films with one, two, and three layers were prepared on a 304 stainless steel surface through the sol-gel method, followed by sintering at 500, 600, and 700 °C. The crystal structure and the surface morphology of the films were characterized by X-ray diffraction and atomic force microscopy. The corrosion resistances of uncoated and coated specimens were studied by electrochemical corrosion tests in a 5% NaCl solution at room temperature. The tribological properties of ZrO2 films were investigated using a tribometer. The results showed that the crystal structure of ZrO2 partially transformed from the tetragonal phase to the monoclinic phase with a rise in sintering temperature. The grain size of the ZrO2 films grew, and the surface roughness of the films increased. However, with an increase in the number of film layers, the grain size and the surface roughness of the ZrO2 films decreased and the films became more uniform and denser. ZrO2 films effectively enhanced the corrosion and wear resistances of the stainless steel surface. With the increase of the sintering temperature and the number of layers in the film, the corrosion resistance of the ZrO2 films increased gradually, but the wear resistance of the films slowly decreased. The film with three layers, which was sintered at 700 °C, had the highest corrosion resistance. Nevertheless, the film with one layer, which was sintered at 500 °C, exhibited relatively well wear resistance.

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A good quality of SiO2/SiC coating was successfully fabricated on carbon fiber fabric by a novel electrolytic plasma spraying method, where Na2SiO3·9H2O aqueous solution was used as an electrolyte. In this study, we discussed the effect of spraying distance on the coating. The microstructure and composition coating were characterized by scanning electron microscopy with energy-dispersive spectroscopy and XPS, respectively. An effective coating can be easily prepared within several tens of seconds through this approach by adjusting the spraying distance. Results show that the sample oxidation resistance temperature was up to 1000 °C while the spraying distance was 15 mm, and tensile strength increased by 73 MPa after heat treatment at 900 °C for 20 min. The study provides additional insights into the feasibility of modification of carbon fiber fabric. Meanwhile, this method can be expected to extend to the fabrication of other oxide coatings or the modification of the surfaces of other complicated and/or large-scale easily oxidized materials.

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