Structure and properties of CrSiN nanocomposite coatings deposited by hybrid modulated pulsed power and pulsed dc magnetron sputtering

CrSiN nanocomposite coatings were deposited at room temperature in a closed field unbalanced magnetron sputtering system by co-sputtering from Cr and Si targets using modulated pulsed power magnetron sputtering (MPPMS) and pulsed dc magnetron sputtering (PDCMS), respectively. The application of MPPMS as one of the sputtering sources was aimed at generating a high ionization degree of the sputtered material and a high plasma density by using a pulsed high power approach. When the Si content is less than 4.8 at.%, Si atoms mainly go into the CrN lattice and form a solid solution. As the Si content reached 6.7 at.%, a nanocomposite structure formed in the CrSiN coatings, in which 5–8 nm Cr(Si)N nanocrystallites were embedded in an amorphous Si3N4 matrix. The solid solution strengthening and complete phase separation are believed to be responsible for the enhanced mechanical properties of the CrSiN coatings. A maximum hardness of 38 GPa, an H/E ratio of 0.096 and an H3/E*2 ratio of 0.31 GPa were identified in the coating with a Si content of 6.7 at.%. The coatings with a Si content at 6.7 at.% and 10.2 at.% were found to be optimized for wear resistant applications. The MPPMS + PDCMS CrSiN coatings also exhibited improved corrosion resistance as compared to AISI 304 stainless steel samples tested in a 3.5 wt.% NaCl aqueous solution.