Effect of Si Content on Structure and Friction and Wear Properties of CrSiN Coatings

Abstract

CrN coatings with different Si contents were prepared on YG6 substrates by DC magnetron sputtering. The phase composition, morphology and element composition of the coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The hardness and adhesion of the coatings were measured by digital microhardness tester and scratch tester. The tribological properties were investigated by a friction and wear tester. The results show that all CrSiN coatings present (111), (200) oriented NaCl structure. With the increasing of Si content, the compactness of the coating increases. When Si content is low, the structure of CrSiN/YG6 coating is relatively loose and triangular granular growth. When Si content is high, the structure of CrSiN/YG6 coating is compact and circular growth. Doping Si element in CrN coating changes the crystalline structure of the coating, and four kinds of CrSiN coating are harder than CrN cating. The hardness of CrSiN/YG6 coatings increases first and then decreases with the increase of Si content. When Si atom fraction is 14.1%, the hardness of the coatings reaches the maximum value of 23.4 GPa. With the increase of Si content, the bonding force between the coatings and the matrix decreases at first. The friction coefficient of CrSiN coatings increases with the increase of Si atom fraction, but the wear rate decreases first and then it increase. When the atomic fraction of Si is 14.1%, the minimum wear rate is 0.602*10−8 mm3*(N.mm)−1. Adding appropriate amount of Si element can improve the hardness and wear resistance of CrSiN coating, and has a certain lubrication effect.