Microstructure and mechanical properties of coated cermets modified by hot isostatically pressing

To increase the adhesion strength between coating and substrate, sintered cermets were selected and deposited with monolayer TiN using a multi-arc ion-plating techniqe and performed with hot isostatic pressing (HIPing) treatment at 1000 °C using nitrogen pressures up to 110 MPa. The mechanical properties of cermets after a coating process and subsequent HIPing treatment have been evaluated with respect to the hardness, residual stress and coating adhesion. The results show that TiN coating of cermets with lower surface roughness had a higher critical load than that with a higher surface roughness. In all cases the residual stress is found to be compressive. The effects of substrate surface roughness and post-treatment on the adhesion strength of coatings were thus investigated. It was also found that the post-treatment process is well-suited for increasing the adhesion strength between the coating and the substrate.