Effect of Cu Doping on Microstructure and Properties of TiN_x-Cu Thin Films on TA2 Titanium Alloy Surface

TiN_x-Cu thin films with different copper contents are prepared by hot wire enhanced plasma magnetron sputtering system, and their hardness, abrasive resistances, corrosion resistances and anti-biological fouling performances are tested. When the Cu target current increases from 1.0 A to 2.0 A, the doping amount (atomic fraction) of Cu increases from 1.21% to 24.07%, and the superfluous Cu gathers on the sample surface. As a result, the film-substrate co-deformation ability is improved, and the hardness and wear-resisting property degrade, with harness decreasing from 34.8 GPa to 3.9 GPa, and the width of wear scratch increasing from 375 μm to 467 μm. Small doping amount of Cu can improve the corrosion resistance of TA2 substrate, but excess doping amount of Cu can make Cu ion’s overflow rate increase, thus the corrosion resistance decreasing, with the self-corrosion potential decreasing from (89.8±3.8) mV to (-179.7±2.2) mV, and the self-corrosion current density increasing by two orders of magnitude, thus. When the Cu target current is 1.0 A, the Cu doping amount is optimu, and the TiN_x-Cu thin film can make the TA2 alloy have excellent comprehensive properties.