Structure and cutting performance of Ti-DLC films prepared by reactive magnetron sputtering

Abstract

Diamond-like carbon (DLC) films that are doped with Ti and coated a Ti interlayer are produced by direct current reactive sputtering using a Ti target and plasma that is a mixture of butane and Ar. This study determines the effect of [Rb = C4H10/(Ar + C4H10) flow ratio], which varies from 6 to 20%, on the morphological and mechanical properties, the structure and the cutting performance of a cutter that is coated using a Ti-DLC film with a Ti interlayer. The Ti-DLC layer has a columnar structure and grows outwards from the Ti interlayer interface and throughout the film. The growth rate for the Ti-DLC film gradually decreases as the Rb flow ratio increases. As the Rb flow ratio increases, the ID/IG ratio and the position of the G-peak increase and then decrease. This result shows that a higher concentration of butane causes a slight transition from sp3 (diamond-like) to sp2 (graphite-like) bonds in the DLC films. A Rb flow ratio of 10% gives a lower coefficient of friction (0.414) and decreased hardness, but the hardness value remains high (12.11 GPa). Ti-DLC films with a Ti interlayer films are coated onto cutter inserts and used for the dry cutting of an Al-7075 alloy workpiece. The coated cutter causes fewer surface defects on the workpiece and exhibits decreased flank wear, so the cutting quality is increased and the service life of the cutter is prolonged.