The kinetics of multilayered titanium-silicide coatings grown by the pack cementation method
- Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
The halide-activated, pack cementation coating method is a viable technique for forming silicide diffusion coatings that provide oxidation resistance for titanium alloys at high temperature. In this study, growth rates were determined for the five-layered silicide coatings on commercially pure titanium grown at 950 C, 1050 C and 1150 C using three halide activators. Solid-state titanium-silicon diffusion couple experiments were also made to determine the diffusional growth rates for the five silicide phases. Based on a model for growth of multiple layers, solid-state diffusion controls the growth rates in all of the silicide layers for coatings formed by packs with the less stable AlF{sub 3} and CuF{sub 2} activators. However. the growth of TiSi{sub 2} was influenced by gas-phase transport for coatings formed using the more stable MgF{sub 2} activator. The growth rates of the layers (TiSi{sub 2}, TiSi, Ti{sub 5}Si{sub 4}, Ti{sub 5}Si{sub 3}, and Ti{sub 3}Si) are parabolic; by assuming solid-state fusion control, the diffusion coefficients in these phases were calculated.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 42853
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 4 Vol. 26; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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