Self-healing effect of silica-based coatings induced by scratches of modified steel substrate

This paper presents the self-healing properties of sol-gel SiO2 coatings doped with CeO2 nano-powders to incite this effect. The built-in ability to self-repair damage was investigated after intentionally introducing scratches during the scratch test. The changes in the morphology of the coating-substrate system were examined by scanning electron microscopy (SEM), transmission electron microscope (TEM) and confocal microscopy. X-ray powder diffraction was used to study the phase composition of the CeO2 nano-powders. A progressive scratch test, multi-scratch test, and electrochemical impedance spectroscopy (EIS) were used to analyze the functional changes in the newly obtained silica coatings. Introducing the CeO2 sol-gel nanoparticles into the coating influences its wear behavior in the multi-scratch test, enabling the formation of the transfer film that lowers the friction coefficient when scratched. Cerium nano-powder dopants also increase the adhesion and wear protection of coatings on steel substrates. Modifying the SiO2 coatings by CeO2 nano-powders enables the most effective long-term protection of the surface of pressure vessel steel type P265GH against corrosion. The research was partially supported by the National Science Centre, Poland under the OPUS + LAP project ‘Research on the influence of self-healing, organic-inorganic sol-gel layers on the corrosion resistance and fatigue of steel in the VHCF range’ UMO-2020/39/I/ST5/03493.