Magnetron-sputtered oxidation protection coatings for Mo-Si-B alloys

Oxidation protective Mo-70Al, Mo-37Si-15B and Mo-46Si-24B (at.%) coatings with 5-10 mu m thickness were deposited on Mo-9Si-8B alloys by magnetron sputtering; and their oxidation behavior was studied at 800, 1000 and 1300 degrees C in air. On the Mo-70Al layer a dense aluminum borate scale grew at 800 degrees C; however, this coating rapidly degraded at 1000 degrees C linked to substrate oxidation at uncoated areas. The Mo-37Si-15B and Mo-46Si-24B layers provided oxidation protection to the Mo-Si-B alloy at 800 and 1000 degrees C for up to 100 h due to formation of a borosilicate scale. The latter coating was protective for short times even at 1300 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.