| 摘要 |
An article of Nb, Ta or base alloys thereof having Ti at least at its surface is provided with an oxidation resistant coating of WSi2 and/or MoSi2 by heating the article in a fluidized bed consisting of SiO2, Al2O3, ThO2 or ZrO2, or mixtures thereof, Mo and/or W, Si and iodine vapour. The coated article may be heated in a similar fluidized bed, but without any Mo or W, to deposit a layer of Si on the disilicide coating. The bed may be fluidized by the passage of an inert gas such as argon which carries the iodine vapour. Ti may be alloyed with the Nb and/or Ta of the article, or present as a coating upon the surface of the base metal, which itself may be a Ti-containing alloy of Nb and/or Ta. ATi coating on such a base metal may be provided by the process claimed in Specification 1,043,578. Among examples of Nb-base alloys specified are those containing: (1) 10% Ti and 10% Mo, (2) 5-15% W, 1-3.5% Zr and 0.05-0.1% C, (3) 33% Ta and 0.75% Zr, (4) 15% W and 5% Mo, (5) 10% Ti and 5% W, and (6) 10% W, 10% Ti and 6% Mo. |
