Development of UMS coatings for hard chromium replacement

Unbalanced magnetron sputtering (UMS) is a physical vapor deposition process that provides great flexibility in process control and allows coating microstructures and properties to be closely tailored to specific service requirements. Chromium nitride coatings have been deposited onto an ultrahigh-strength steel (AISI 4340) by the UMS process. The influence of processing conditions on coating microstructures and mechanical properties is discussed in this paper. The coatings exhibit higher hardness and better erosion resistance than electroplated hard chrome (EHC). Magnetron sputtering of chromium nitride offers a promising alternative for EHC in applications requiring wear and/or corrosion resistance, especially where smooth surface finish is highly desirable, where low deposition temperature is required, and for components that are relatively small and intricately shaped.