AlCrN Coated WC by PVD at Various Deposition Temperatures

Abstract

An attempt is made in this work to improve the performance and tool life of the tungsten carbide (WC) coated aluminium chromium nitride (AlCrN) via physical vapor deposition (PVD) method. Various deposition temperatures ranging from 250, 350, 400, and 450 oC were investigated to evaluate the characteristic of coated carbide. Prior to the deposition process, WC surfaces were treated in Murakami’s solution for 15 minutes followed by Caro’s solution for 10 seconds to improve the coating adhesion on WC by the dissolution of cobalt (C); roughened the carbide surface. The thickness of the coated AlCrN increases proportional with higher deposition temperatures (from 1.14 μm to 2.18 μm) and homogenously coated. While XRD analysis observed the presence of AlN and CrN phases attributed to AlCrN coating. The hardness of the coated carbide was highest at 450 oC deposition temperature (1325 HV). The qualitative scratch test following ASTM D 3363 indicated that higher temperature (400 oC and above) provides good adhesion characteristics between AlCrN coating and WC.