| 摘要 |
A high-temperature nickel or cobalt base super alloy containing at least 50% by weight of nickel and/or cobalt is coated with a diffusion coating comprising chromium and aluminium by embedding the super alloy in a pack containing a source of chromium and aluminium metal and a source of a vaporizable halogen and heating the super alloy in the pack. The pack contains 3% to 20% by weight of aluminium and 2 to 4 times that amount of chromium and the super alloy is heated to at least 1800 DEG F. In a specific embodiment the pack consists of 69% alumina, 22% chromium, 8% aluminium and 1% iodine the super alloy being embedded in the pack and heated for 4 to 20 hours at 1800 DEG F. to 2100 DEG F. Ammonium iodide or ammonium fluoride may be used instead of the iodine and two examples of the super alloys so treated are a high nickel alloy containing 0.12% C, 19% Cr, 19% Co, 1% Fe, 4% Mo, 3% Al, 3% Ti, and a high cobalt alloy containing 0.5% C, 24.5% Cr, 10.5% Ni, 7.4% W, 1% Fe and 55% Co. |
