High temperature oxidation resistance of Ti-5553 alloy with electro-deposited SiO2 coating

• Published in: Materials chemistry and physics 2022-01, Vol.275, p.125306, Article 125306
• Main Authors: Xu, Shenghang, Lu, Tingting, Shen, Kaijie, Lan, Junjie, Hu, Bin, Zhang, Huibin, Tang, Yiping, Cao, Huazhen, Zheng, Guoqu
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Cathodic coating (process); Coating; Deposition; Diffusion layers; Electro-deposition; Heat resistant alloys; High temperature; Mechanical properties; Oxidation; Oxidation resistance; Residual stress; Scale (corrosion); Silicon dioxide; SiO2 coating; Ti-5553 alloy; Titanium alloys; Titanium base alloys; Titanium dioxide
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.125306

Ti–5Al–5V–5Mo–3Cr (Ti-5553) metastable β titanium alloy possesses excellent high temperature mechanical properties, however, the oxidation resistance is fairly poor. In this work, a SiO2 coating was prepared on Ti-5553 alloy by cathodic electro-deposition. The high temperature oxidation resistance of the deposited SiO2 coating was evaluated at 800 °C. The results show that the optimal current density of deposition is −2.0 mA/cm2 for 300 s, and the thickness of the compact SiO2 film reaches 5.5 μm. The SiO2 film can react with Ti-5553 substrate and form protective Ti5Si3 layer, which inhibits the inward diffusion of oxygen from air, leading to the remarkable improvement of oxidation resistance. The mass gain is only 1.13 mg/cm2 after oxidation at 800 °C for 80 h. The oxide scale consists of TiO2, Al2O3, V2O5, Cr2O3 and SiO2, but Mo2O5 is absent. The occurrence of Kirkendall voids as well as the cracks induced by internal stress should be responsible for the deterioration of oxidation resistance, which may provide extra channels for oxygen diffusion inwards the substrate. •Thickness controllable SiO2 coating can be prepared on Ti-5553 substrate by electro-deposition.•The thermal oxidation resistance of Ti-5553 alloy is evidently improved.•The elemental diffusion of Ti-5553 alloy at high temperature oxidation were investigated.•The mechanism of thermal oxidation resistance of the SiO2 protective coating was provided.