Microstructure and mechanical properties of Cr films with different orientations before and after plasma nitriding.

In this paper, the Cr films with preferred orientation evolution from (110) to (200) were deposited on the surface of austenitic stainless steel. These films were driven by a pulsed bias with different duty cycles from 20% to 80%, followed by a postnitriding process for 1 h using a hot wire plasma-enhanced magnetron sputtering system. XRD result showed Cr film had a body-centered cubic lattice structure, and the orientation transformed from (110) to (200) with the increase in the duty cycle. SEM and EDS measurements revealed that Cr film structured with columnar crystals could contribute to the continuous diffusion of nitrogen into austenite lattice. N atoms tended to diffuse along the (200) orientation of Cr films than the close-packed (110) orientation. As a result, the best wear resistance and adhesion strength were obtained when Cr film deposited at 80% duty cycle was nitrided, and the wear volume decreased by 95.7% compared with that before nitriding. [ABSTRACT FROM AUTHOR]