Acquisition and properties of wear-resistant PVD/CVD coatings on a hard-alloy tool

The processes of structure and phase formation during the formation of combined physical deposition (PVD)/chemical deposition (CVD) coatings on a hard-alloy tool are investigated. It is shown that the formation of the Cr PVD barrier layer prevents the formation of the η phase with the subsequent deposition of the TiC-Ti(C,N)-TiN CVD coating. Treatment of the CVD coating with the ion-plasma flow and deposition of the finishing TiN PVD layer lead to the formation of the texture {111} in the coating and the diminishment of its subgrains to ∼30 nm. Upon going from articles with CVD coatings to combined PVD-CVD-PVD coatings, the strength and hardness of hard-alloy blades increase. This is explained by the effect that the corresponding phase and structural transformations that occur in the coating and at the phase interfaces during their formation have on these characteristics. The results of certification tests of cutter tools for continuous and intermittent cutting indicate the efficiency of these coatings both for turning work and, especially, for mill operation, when high toughness, along with hardness, is the most important characteristic.