Effect of different Si addition on oxidation resistance of titanium aluminum coating at 900 °C

Abstract

Abstract The Ti-6Al-4V substrate was used as the laser cladding material, and the fiber laser was used to scan and form a titanium-aluminum composite coating in situ. Ti5Si3 reinforcing phase is formed in situ by the reaction between Si and Ti in the base material, the oxidation behavior of 50 h at a high temperature of 900 °C was studied by adding different amounts of Si (0, 1.25, 2.5, 3.75 and 5 mol.%). The experimental results show that the mass gain of TC4 high temperature oxidation (50 h at 900 °C) is 120mg/cm2, and the titanium aluminum coating with different contents of Si decreases to 60, 45, 42, 30 and 40mg/cm2. The addition of Si (3.75 mol.%) in the coating greatly increases the oxidation resistance at high temperatures. The addition of Si inhibits the affinity of Ti and O elements, resulting in the Ti5Si3/γ-TiAl composite coating producing more Al2O3 at high temperatures, which is more dense than the Al2O3 produced by the loose Ti-6Al-4V substrate of TiO2. Under the condition of high temperature oxidation at 900 °C for 50 hours, the oxidation resistance of TiAl-3.75Si is the best at high temperature.