| abstract |
A cutting tool insert comprises a hard metal substrate having at least two wear-resistant coatings including an exterior ceramic coating and a coating under the ceramic coating being a metal carbonitride having a nitrogen to carbon atomic ratio between 0.7 and 0.95 which causes the metal carbonitride to form projections into the ceramic coating improving adherence and crater resistance of the ceramic coating. Also disclosed is a cutting tool insert including a hard substrate and at least first and second coatings on at least a portion of said substrate. The first coating is of at least about 2 microns, is in contact with the substrate, and includes at least one of a metal carbide, a metal nitride, and a metal carbonitride of a metal selected from the group consisting of zirconium and hafnium. The second coating may include at least one of a metal carbide, a metal nitride, and a metal oxide of a metal selected from groups IIIA, IVB, VB, and VIB of the periodic table. |