Improvement in wear and corrosive wear resistance of Ti6AI4V alloy by double glow plasma surface alloying with W-Mo and W-Mo-N

摘要

W-Mo and W-Mo-N surface-modified layers on Ti6A14V alloy were obtained using a double glow plasma surface alloying technique. The morphology, microstructure, and chemical composition distribution of the modified layers were analyzed by scanning electron microscope, X-ray diffraction, and glow discharge optical emission spectrometry. The hardness and toughness of the modified layers were measured using a micro-hardness tester, and dynamic repeating press equipment. The wear resistance in ambient air and the corrosive wear resistance in NaCl solution were evaluated using a ball-on-disk wear tester. The results show that W-Mo and W-Mo-N surface modified layers are composed of the alloying layers which vary in composition and phase form along the depth. A microhardness gradient was observed in the modified-surface layers. The surface hardness of the W-Mo-N and W-Mo modified layers was 25.3 and 14.2 GPa, which is seven-fold and 3.9-fold harder than the Ti6A14V substrate, respectively. W-Mo and W-Mo-N surface-modified layers significantly improved the wear and corrosion resistance of Ti6A14V. It seems that the wear resistance of W-Mo and W-Mo-N surface-modified layers in NaCl solution is better than that in ambient air owing to the strong lubricating effect of NaCl solution and the excellent corrosion resistance of the modified layers.