Microstructure of Metallorganic Chemical Vapor DepositedudAluminum Coatings on Ti6242 Titanium Alloy

摘要

Al-based alloys are used in aeronautics as a protective layer against the excessive oxidation of turbines blades. In this work, Al coatings were deposited by metallorganic chemical vapor deposition on Ti6242, a commercial titanium alloy, with Pt as a sublayer or codeposited to ensure this protection, eventually forming platinum aluminides. Continuous Al coatings were deposited on bareudTi6242, using both triisobutylaluminum and dimethylethylamine alane as precursors. The same operating conditions applied on a platinum sublayer lead to discontinuous layers mainly containing whiskers. The introduction of a surfactant, namely, ethyl iodide,udin the input gas improves the coating morphology by providing nearly whisker-free continuous films, suitable for oxidation protection. Codeposition of Pt and Al results in reduced growth rate and yields layers with lower Pt content and with specific morphology. This behavior is attributed to the competition between Al and Pt compounds on the growing surface.