Mechanical and tribological properties of Cr–N and Cr–SI–N coatings reactively sputter deposited

Abstract

Cr–N and Cr–Si–N coatings have been deposited with two nitrogen flow rates, 6 and 10 sccm, for a constant argon flow rate of 20 sccm with various amounts of silicon, in an ALCATEL SCM 650 sputtering system. DC and pulsed DC were used to power the target and the silicon coupons, placed in the erosion track, whereas the substrate holder was RF biased. All the deposited coatings are dense and well bonded to the M2 steel substrates. At 10 sccm N2, the increase of the silicon content up to 2.5 at.% into the coating leads to a maximum hardness (H) and a low Young's modulus (E). A further increase of the Si content yields to both the decrease of H and E. At 6 sccm N2, a similar but less pronounced phenomena are observed.Ball on disk tests under a normal load of 5 N applied to a 100Cr6 ball were performed to investigate the wear resistance of the coatings. Cr–Si–N coatings showed low friction coefficients and no measurable wear after 500 m of sliding at 0.2 m s−1.