Deposition, structure and hardness of Ti–Cu–N hard films prepared by pulse biased arc ion plating

In this work, Ti–Cu–N hard nanocomposite films were deposited on 304 stainless steel (SS) substrate by using pulse biased arc ion plating system with Ti–Cu alloy target. The effects of negative substrate pulse bias voltages on chemical composition, structure, morphology and mechanical properties were investigated. The composition and structure of these films was found to be dependent on the pulse bias, whereas the pulse biases put little influence on hardness of these films. The XPS spectra of Cu 2p showed that obtained peak values correspond to pure metallic Cu. Cu content in Ti–Cu–N nanocomposite films changed with pulse bias voltage. In addition, X-ray diffraction analysis showed that a pronounced TiN (111) texture is observed under low pulse bias voltage while it changed to TiN (220) orientation under high pulse bias voltage. Surface roughness of the Ti–Cu–N nanocomposite films achieved to the minimum value of 0.11 μm with the negative pulse bias voltage of −600 V. The average grain size of TiN was less than 17 nm. The mechanical properties of Ti–Cu–N hard films investigated by nanoindentation revealed that the hardness was about 22–24 GPa and the hardness enhancement was not obtained.

► The pulse bias had significant effect on the composition and structure of the films.
► The change of preferred orientation was observed with pulse bias voltage increasing.
► It was presumed to have a nc-TiN/nc-Cu structure in this present work.