| 摘要 |
1,266,241. Aluminized Ni superalloys. UNITED AIRCRAFT CORP. Oct. 7, 1969 [Oct. 8, 1968], No.49251/69. Headings C7D and C7F. An aluminide coating is formed on a Ni superalloy by aluminizing e.g. by pack cementation, hot dipping, flame or plasma spraying, fused salt electrolysis or slurry coating, followed by heattreatment above 1149‹C. and then precipitation heat-treatment. The surface roughness of the substrate prior to coating is preferably 28À5 microns per cm (65 microns per inch) maximum. Coating preferably is effected in a pack of 15% Al, 3% NH 4 Cl and 82% Al 2 O 3 at 982‹C, or by applying a slurry of Al and Si powders ratio 9:1 in cellulose acetate. A UDIMET 700 (Trade Mark) alloy is aluminized, diffusion heat-treated at 1079À5‹C., heat-treated at 1171‹C. and precipitation heattreated at 1079À5‹C. for 4 hours, air cool; 843‹C. for 24 hours, air cool; 760‹C. for 16 hours and air cool. Several examples of Ni superalloys are given and the process is particularly suitable for treatment of gas turbine blades. |
