Sliding wear behavior of polycrystalline TiN/CrN multilayers against an alumina ball

Sliding wear experiments were conducted using a ball-on-disc rotating friction apparatus to evaluate the wear behavior and properties for TiN, CrN and TiN/CrN multilayers with different modulation periods deposited on WC/Co cemented substrates with reactive magnetron cathodic sputtering. TiN showed the higher coefficient of friction of 0.9 and the higher wear rate due to the larger debris as abrasive remained on wear scar. It was found that the coefficient of friction of TiN/CrN multilayers against the alumina ball ranged from 0.3 to 0.5. TiN/CrN multilayer at Λ of 21 nm, possessing the maximum hardness enhancement, showed the smallest friction coefficient value of 0.3. The lower coefficient of friction of TiN/CrN multilayers corresponds to the enhancement of hardness, the promotion of the formation of the dense Cr2O3, and CrO3 oxide layer, and the exclusion mechanism of debris from the wear scar. The wear volume of TiN/CrN multilayers was decreased with one digit in comparison with that of TiN single layer coatings. TiN/CrN multilayer technique, by enhancing the hardness, promoted the formation of an oxide layer on the wear scar. The dense Cr2O3 and CrO3 oxide layers help to build additional protective films on the worn surface, induce a lower coefficient of friction and will contribute to the decrease of wear loss for TiN/CrN multilayers.