Sintered hard metal and the method for producing the same

Claim 1

A sintered hard metal having a B-1 type crystal structure composed of a hard phase and a WC phase as well as a bonding phase chiefly composed of ferrous metals, characterized in that said hard phase consists essentially of at least two different kinds of metals selected from Group IVb, Vb and VIb metals of the Periodic Table in combination with carbon, nitrogen and oxygen which hard phase is represented by the molecular formula (M A , M' B M" C ) (C u N v O w ) z wherein M represents Group IVa metals, M' represents Group Va metals and M" represents Group VIa metals, A, B, C and u, v, w represent the atomic ratio of the elements in the formula, and z represents the ratio of the total number of the metallic atoms to that of C,N,O atoms, with the relationship such that A+B+C=1, u+v+w=1, A≧O, B≧O, A+B>O, C>O, u>O, z≧0.6, and 0.005<+w≦0.5 and 0.005<W<0.5.

Claim 6

A method for producing a sintered hard metal having a B-1 type crystal structure composed of a hard phase and a WC phase as well as a bonding phase chiefly composed of ferrous metals, and wherein said hard phase consists essentially of at least two different kinds of metals selected from Group IVa, Va and VIa metals of the Periodic Table in combination with carbon, nitrogen and oxygen, which hard phase is represented by the molecular formula (M A , M' B , M" C ) (C u N v O w ) z wherein M represents Group IVa metals, M' represents Group Va metals and M" represents Group VIa metals A, B, C and u, v, w represent the atomic ratio of the elements in the formula, and z represents the ratio of the total number of the metallic atoms to that of C,N,O atoms, with the relationship such that A+B+C=1, u+v+w=1, A≧O, B≧O, A+B>O, C>O, u>O, z≧0.6, and 0.005<v+w≦0.5 and 0.005 W<0.5, which sintered hard metal of the above formula is produced by mixing two or more different kinds of Group IVa, Va, or VIa metal compounds selected from oxides, carbides and nitrogen containing compounds of said metals with WC and iron Group metals which make up a bonding phase, the whole of said mixture being pressed into a predetermined shape and sintered, said sintering being performed in a CO partial pressure atmosphere above 5 Torr during all or part of the time during which the sintering temperature is in excess of 600° C. and in a vacuum atmosphere below 10 -1 Torr during all or part of the time at which a liquid phase appears.

Claim 7

A method for producing a sintered hard metal having a B-1 type crystal structure composed of a hard phase and a WC phase as well as a bonding phase chiefly composed of ferrous metals, and wherein said hard phase consists essentially of at least two different kinds of metals selected from Group IVa, Va and VIa metals of the Periodic Table in combination with carbon, nitrogen and oxygen, which hard phase is represented by the molecular formula (M A , M' B , M" C ) (C u N v O w ) z wherein M represents Group IVa metals, M' represents Group Va metals and M" represents Group VIa metals A, B, C and u, v, w represent the atomic ratio of the elements in the formula, and z represents the ratio of the total number of the metallic atoms to that of C,N,O atoms, with the relationship such that A+B+C=1, u+v+w=1, A≧O, B≧O, A+B>O, C>O, u>O, z≧0.6, and 0.005<v+w≦0.5 and 0.005 W<0.5, which sintered hard metal of the above formula is produced by mixing two or more different kinds of Group IVa, Va, or VIa metal compounds selected from oxides, carbides and nitrogen containing compounds of said metals with WC and iron Group metals which make up a bonding phase, the whole of said mixture being pressed into a predetermined shape and sintered, said sintering being performed in a CO partial pressure atmosphere above 5 Torr during all or part of the time during which the sintering temperature is in excess of 600° C. and in a vacuum atmosphere below 10 -1 Torr during all or part of the time at which a liquid phase appears.