Adherent coating on gradient cemented carbide with ultrafine Ti(C_(0.5),N_(0.5))

Gradient cemented carbide is usually employed as the substrate for coated carbide insert. In this work,gradient cemented carbide with ultrafine Ti(C_0.5,N_0.5) was prepared and its microstructure and properties were researched. Moreover, this novel substrate was coated to investigate cutting performance. It is found that the average WC grain size in the gradient zone is larger than that in the bulk. Owing to ultrafine Ti(C_0.5,N_0.5) introduction, gradient cemented carbide prepared by vacuum sintering exhibits full densification. By contrast, the gradient cemented carbide with ultrafine Ti(C_0.5,N_0.5) shows higher transverse rupture strength(TRS) and hardness than the homogenous one. Gradient cemented carbide suffers small TRS reduction after coating, and the bonding between coatings and gradient substrate is tidy and compact. The coated gradient cemented carbide shows much better endurance and impact resistance than the coated homogenous one. It confirms the superiority of gradient cemented carbide when used as the substrate for coating inserts.