XI Fangxingyue, HU Tingting, FU Xuesong, CHEN Guoqing

(Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116085, Liaoning, China)

Abstract: With SiO₂, Al₂O₃, MgO, CaO and B₂O₃ as the raw materials and sodium silicate as the binder, ceramic coating was prepared on the surface of titanium alloy by using slurry method. Microstructure, microhardness and corrosion resistance of the coatings were studied. It was demonstrated that the coating was dense and uniform, with SiO₂ as the main component and MgSiO₄ and CaSiO₃ as the minor phases. Pits and holes were observed on the coating surface after corrosion for 15 days. The coatings were thinned obviously after corrosion for 30 days. After 60 days, although the number of the pits was increased and the size was enlarged, the coating was still closely combined with the substrate. After corrosion for 60 days, the fracture toughness of the coating was decreased from 3.75 MPa·m^-1/2 to 2.45 MPa·m^-1/2, while the microhardness was reduced from HV 549.2 to HV 428.6, which are however still higher than that (399.3 HV) of the titanium alloy without coating. After corrosion for 60 days, self-corrosion current of the coating was 0.32 μA/cm² and the polarization resistance was 342.5 kΩ·cm², while the self-corrosion current of the substrate was 1.32 μA/cm² and the polarization resistance was 18.9 kΩ·cm². In conclusion, the ceramic coating has potential for practical long-term anti-corrosion applications.

Key words:  titanium alloy; slurry method; ceramic coating; corrosion resistance