Process and composition for chromizing 400-series stainless steels
AssigneesMcDermott Technology, Inc., The Babock & Wilcox Company
InventorsDouglas D. Zeigler, James M. Tanzosh, George H. Harth, Walter R. Mohn
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Abstract
An improved process for chromizing and chrome-siliconizing 400-series stainless steel components, and in particular, 430 stainless steel components, such as boiler panel studs. The process includes the addition of between 0.12%-0.25% by weight of calcium fluoride salt to the conventional 4% by weight of ammonium chloride activator salt to the coating composition used in known diffusion coating processes. In a more preferred embodiment, small amounts of silicon powder, such as between about 0.12%-0.25% by weight, are added to the two salts and the diffusion coating material. A coating composition is provided as well.
Claims9
A method of producing a stainless steel product having a protective coating comprising:
- combining about 0.12%-0.5% wt. of a fluoride compound, 4% wt. of ammonium chloride and the remainder one of chromium and chromium-silicon to form a diffusion coating composition;
- providing at least one stainless steel component;
- forming a diffusion coating on the at least one stainless steel component using the diffusion coating composition.
Dependencies are inferred from the claim text.