Patent ID: 6293739
Filing Date: 2001-09-25
Classification: C23C,Y10T

Abstract:
A coated cemented-carbide cutting tool comprising:(1) a cemented-carbide substrate that comprises:(a) a hard phase comprising:(a1) tungsten carbide as the main constituent; and(a2) at least one member selected from the group consisting of carbide, nitride, and carbonnitride of the metals in the IVa, Va, and VIa groups; and(b) a bonding phase mainly consisting of Co; and(2) a ceramic coating layer on the cemented-carbide substrate, the ceramic coating layer comprising an inner layer in contact with the cemented-carbide substrate and an outer layer on the inner layer, wherein(a) the inner layer comprises at least one layer of Ti(CwBxNyOz), where w+x+y+z=1, and w, x, y, and z.gtoreq.0, and(b) the outer layer comprises Al.sub.2 O.sub.3 comprising grains of .alpha.-Al.sub.2 O.sub.3 and a region with a row containing coexisting grains having an .alpha.-type crystal structure and grains having a .kappa.-type crystal structure, each in contact with the inner layer, wherein regions having crystal grains of .alpha.-Al.sub.2 O.sub.3 have substantially no pores.