Laser treatment and PVD TiN coating of Ti-6Al-4V alloy

Improved adhesion between a coating and the base substrate is necessary for successful engineering applications. This may be achieved through generating intermediate zone between the coating and the substrate. In the present study, laser gas alloying of Ti-6Al-4V alloy was carried out. Nitrogen was introduced co-axially with the laser beam while the workpiece is scanned at a constant speed in the x-direction during the laser heating process. The laser-treated workpieces were then slightly ground and TiN PVD coated. Thickness of the coating layer was limited to 2 mum. The wear tests were conducted on the laser-treated TiN-coated workpieces. To examine the metallurgical changes, microphotographs of workpiece cross-sections were taken. To monitor the nitride compounds in the surface region, XRD was carried out. It was found that three wear stages occur. The steady wear stage is relatively longer for laser-treated TiN-coated workpiece compared to the TiN-coated workpiece. (C) 2001 Elsevier Science B,V. All rights reserved.