Influence of Cr contents and nanograin sizes on microstructure, mechanical and sliding tribological behaviors of hard Cr-diamond-like carbon films

The influence of Cr content and nanograin size on the microstructure, the mechanical and sliding tribological behaviors of Cr-containing diamond-like carbon (Cr-DLC) films, deposited on (100) Si substrate by a mid-frequency dual-magnetron system, was explored. The Cr-containing nanoparticles (combining Cr with C) were dispersed in the amorphous DLC matrix while some nanoparticles were transformed into compounds of C/Cr. The incorporation of Cr into Cr-DLC films improved the crystallinity of the Cr-rich nanoparticles and partially converted the nanoparticles to Cr/C phase. The films with Cr content ranging between 5∼10 at% and with Cr-containing nanograin sizes in range of 15∼27 nm were found to possess higher hardness, lower intrinsic stress, lower coefficient of friction (COF) and wear rate than those of 16∼28 at% Cr content and 46∼74 nm nanograin sizes. The superhard Cr-DLC film with 8.3 at% Cr and 18.4 nm Cr-containing grain gave the favorable micro-tribological characteristics with COF at μ≈ 0.1 and wear rate at 3.6-10 ^-8 mm ³/Nm. Copyright© 2010 American Scientific Publishers.