| 摘要 |
Chromium plating from the trivalent state is relatively environmentally friendly as compared to a hexavalent chromium bath. Incorporation of non-metallic and metalloid elements into the coating should lead to enhanced properties. The relationship between composition, structure, and properties of annealed Cr-C-P layers electrodeposited from chromium-based trivalent baths is discussed. These coatings are amorphous in the as-deposited state, but upon thermal treatments, chromium nanocrystallization, as well as precipitation of carbides and phosphides occurs. Incorporation of phosphorous strongly influences the structural evolution and mechanical properties. Electroplated Cr-C alloy coatings exhibit significant increases in hardness and strength, when exposed to temperatures up to about 600° C., owing to the evolution of their nanostructure. This evolution can be shifted to higher temperatures (approaching 850° C.), through a ternary addition of phosphorous. The resulting Cr-C-P coatings may be suitable for applications at higher service temperatures, where more conventional Cr-based coatings soften rapidly.
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