Influence of the WC grain size on the properties of PVD/HVOF duplex coatings

It was shown that a smaller carbide grain size influences the microstructure of the CrAlN coating and causes a finer crystalline structure. Furthermore, higher compressive residual stresses occur in the duplex interlayer and the top layer when using nanosized carbides. Moreover, nanosized carbides in the HVOF coating are favorable in terms of layer adhesion, which was analyzed by means of HRC indent test and scratch test. Further enhancements are the increase in hardness and the reduction in roughness which was directly influenced by the WC grain size. Considering the obtained results, it is to conclude that a reduction of the interlayer WC grain size improves the performance of CrAlN/WC-12Co duplex coatings.