Synthesis and mechanical properties of CrMoCxN1−x coatings deposited by a hybrid coating system

Quaternary CrMoCxN1−x coatings were deposited on steel substrates (AISI D2) and Si wafers by a hybrid coating system combining an arc-ion plating technique and a dc reactive magnetron sputtering technique using Cr and Mo targets in an Ar∕N2∕CH4 gaseous mixture. The carbon content of CrMoCxN1−x coatings was linearly increased with increasing CH4∕(CH4+N2) gas flow rate ratio. The maximum hardness of 44GPa was obtained from the CrMoCxN1−x coatings containing a carbon content of x=0.33 with a residual stress of −4.4GPa. The average friction coefficient of Cr–Mo–N coatings was 0.42, and it is decreased to 0.31 after applying CrMoCxN1−x coatings. This result was caused by the formation of a carbon-rich transfer layer that acted as a solid lubricant to reduce contact between the coating surface and steel ball. The microstructure of the coatings was investigated by x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy. In this work, the microstructure and mechanical properties of t...