Surface protection of titanium by Ti5Si3 silicide layer prepared by combination of vapour phase siliconizing and heat treatment

In this work we proposed a new method for preparation of protective Ti5Si3 silicide layer. The proposed method consisted of two steps: (1) silicon electron beam evaporation and (2) heat treatment. The silicide-modified titanium was subjected to structural examination, hardness profiling and isothermal oxidation tests. The investigations revealed that the proposed surface treatment produces a layer with a thickness of 1–2 μm and hardness of about 1500 HV. The isothermal oxidation tests showed that the layer is highly resistant to oxidation in air even at 900 °C. Its oxidation rate was comparable or even lower than that of some high-temperature γ-TiAl intermetallics oxidized under similar conditions. The oxidation mechanism was discussed in terms of the internal structure and chemical composition of the scales. It was demonstrated that the silicide layer could serve as excellent protection of titanium, Ti-based alloys and intermetallics against the high-temperature oxidation and wear.