Metal nitride coatings by physical vapor deposition (PVD) for a wear resistant aluminum extrusion die

The purpose of this study is to investigate the friction and wear behaviors of CrN, TiN, CrAlN, and TiAlN coated onto SKD61 for application to Al 7000 series extrusion dies. On the wear test, the experimental parameters are the load and the counter material's temperature. The results showed that the friction coefficient increased with load but decreased with the counter material's temperature, and the friction coefficients of CrN and CrAlN were lower than the friction coefficients of TiAlN and TiN, especially at a higher temperature. The wear track with different coatings identified different wear behaviors; the wear behavior of CrAlN was found to be abrasive, but the wear behavior of TiN, CrN, and TiAlN was adhesive. Therefore, CrAlN showed the least wear loss with a lower friction coefficient and less adhesion with counter materials at the highest range of wear load and temperature. This resulted in the easy formation of aluminum oxide in the wear track and less Al adhesion; moreover during the hard second phase, AlN dispersed in the film during deposition.