Patent ID: 6110603
Filing Date: 2000-08-29
Classification: B22F,C22C,C23C,Y10T

Abstract:
A hard-metal or cermet body composed of a substrate having a hard-material phase selected from the group which consists of tungsten carbide, at least one carbide, nitride, carbonitride or oxycarbonitride of at least one of the elements of Group IVa, Va or VIA of the Periodic Table, and mixtures thereof, and a binder phase making up 3 to 25 mass-percent of the hard-material phase and consisting of at least one of the elements Fe, Co and Ni, and having a multilayer outer region formed by layers of different compositions, wherein:(a) the hard-material phase contains 10 mass-percent to 96 mass-percent WC;(b) a first, outermost one of said layers forms a surface of said body of a substantially binder-phase- free carbonitride phase to a depth between 2 .mu.m and 30 .mu.m from said surface;(c) an intermediate one of said layers is disposed inwardly of and bounds said outermost layer, has a thickness of 5 .mu.m to 150 .mu.m, and is composed of a substantially pure WC--Co composition; and(d) an innermost one of said layers is disposed inwardly of said intermediate layer, has a thickness of at least 10 .mu.m and at most 650 .mu.m, and has proportions of the binder phase and any of said elements of Group IVa or Va of the Periodic Table which increase to a substantially constant value to the proportions of the binder phase and any of said elements of Group IVa or Va of the Periodic Table in said substrate, and a proportion of tungsten which decreases to a substantially constant value of the proportion of tungsten in said substrate.