Fabrication of TiO₂/SiO₂ Composite Coating via a High-Temperature Self-Organizing Microporous TiO₂ Layer on Ti

Abstract

We studied the fabrication of a TiO 2 /SiO 2 composite coating on Ti. At a temperature above 1100 K with oxygen partial pressure, a self-organized coating of rutile phase TiO 2 is formed on a Ti substrate. The thick TiO 2 coating (> 10 μm) had a piecrust-like multilayer structure, which comprise TiO 2 monolayers and gaps. A composite coating containing SiO 2 was fabricated via a sol-gel method in vacuum to improve the exfoliation strength of the brittle, porous TiO 2 coating. Cross-sectional SEM images revealed suf cient amounts of SiO 2 in the gaps between the TiO 2 monolayers in the TiO 2 /SiO 2 composite coating, even at the interface between the oxide coating and the substrate. Exfoliation stress of the composite coating was up to 10-15 times higher than for the self-organized TiO 2 coating alone, and the composite coating s failure mode was interfacial compared with cohesive for the self-organized TiO 2 coating.

Effect of Nb addition on high-temperature oxidation behavior, oxide layer structure, and its exfoliation resistance of Ti-Nb Alloys

“…Since the structure contains multiple void layers, fracture occurs easily at the void layer by the external force, and the exfoliation stress is as low as about 2 ~ 4 MPa [1,4]. However, by introducing a reinforcing material such as SiO 2 glass into the void layer, it is possible to improve the exfoliation stress to about 15 ~ 20 MPa which is durable for practical use [7,8]. The oxide layer formed on the TNTZ alloy is shown in Fig.…”