ALPHA AL2O3 AND TI2O3 PROTECTIVE COATINGS ON ALUMINIDE SUBSTRATES

摘要

A titanium aluminide substrate (4) is vulnerable to air oxidation, limiting the use of this substrate in a variety of industrial applications, including the aircraft and aerospace industries. A bilayer reactive barrier (2) is formed on a titanium aluminide substrate. The barrier layer includes an alpha -Al2O3 layer (6) from the reaction of oxygen from the disassociation of water with alumina in a gaseous and water vapor atmosphere at high temperatures and low oxygen concentration. During the process, titanium migrates through the alpha -Al2O3 to a gas/barrier layer surface (14) and is oxidized to form a Ti2O3 layer (8). A surface of the Ti2O3 layer is subsequently oxidized to form a TiO2 layer (12). In this manner, a triple layer barrier is formed in which the immersible TiO2 and alpha -Al2O3 are separated by Ti2O3. The three layers are bonded to each with a bond strength greater than 69,000 kPa.