Coated PcBN cutting insert, coated PcBN cutting tool using this coated PcBN cutting insert, and process for its manufacture

摘要

A coated polycrystalline cubic boron nitride cutting insert (28; 58; 120) comprising: a polycrystalline cubic boron nitride substrate (70; 126), the polycrystalline cubic boron nitride substrate (70; 126) having a rake face (30; 62) and at least one flank (32; 64) and a cutting edge (34; 66), formed at the meeting of the rake surface (30; 62) and the free surface (32; 64); a wear-resistant coating structure (74, 74A, 129) comprising: an inner coating layer region (94; 150) deposited by chemical vapor deposition on at least a portion of the rake surface (30; 62) and at least a portion of the relief surface (32; 64) of the polycrystalline cubic boron nitride substrate (70; 126) ; an alumina-containing coating layer region deposited by chemical vapor deposition on the inner coating layer region (94; 150), the alumina-containing coating layer region having at least one exposed alumina layer (84, 84A; 138) available by completely removing an outer coating layer portion (86, 88; 140, 142) containing titanium originally deposited by chemical vapor deposition on the alumina containing coating layer portion by means of wet blasting, the stress state of the exposed alumina layer (84, 84A; ) is in the range between 50 MPa tensile stress and 800 MPa tensile stress, measured by XRD using the Psi inclination method and the (024) reflection of alumina, and is modified by the blast treatment so that the exposed alumina layer (84, 84A, 138) has a stress state after blast treatment that is in a range between 50 MPa tensile stress and -2 GPa compressive stress as measured by X-ray diffraction (XRD) using the Psi tilt method and the (024) Reflection of alumina, and wherein the stress state before the blast treatment has a greater tensile stress than the stress state after blast treatment.