| 摘要 |
A method of aluminum diffusion coating the surface of an iron-, nickel-, cobalt-, or titanium-base alloy product begins with cleaning and providing an anchor profile on the surface of the product, followed by depositing with an appropriate thermal spray method at least 4 mils (0.1016 millimeters) thickness of a minimum 85 wt. % aluminum alloy, which can also contain up to 12 wt. % silicon. A MCrAlX-type coating layer is also thermally sprayed on the substrate surface before the aluminum alloy is sprayed. The thermal sprayed products are heat treated in a sealed retort at a temperature of between 900 DEG F. and 1200 DEG F. (482 DEG C. and 649 DEG C.) and then maintained at that temperature for a period of at least one hour to ensure the formation of a strong metallurgical bond between the aluminum alloy layer and the product. The retort temperature is then elevated to between 1400 DEG F. and 2000 DEG F. (760 DEG C. and 1093 DEG C.) and held at that temperature for between 0.17 hour (10 minutes) and 7 hours to cause the diffusion of the aluminum alloy surface layer and subsequent formation of an aluminum diffusion coating. A further treatment step after diffusion heat treatment can be conducted to form a surface oxide, nitride, or combination surface layer. Abrasive blasting of the finished aluminum diffusion coated product may be done to remove any residual aluminum alloy overlay remaining on the coating surface and to provide an improved surface finish and appearance.
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