US 5,670,726 A · Cermet and method of producing it

Abstract

In order to improve the toughness characteristics of a cermet alloy, while retaining high resistance to wear, a composition is disclosed which contains 30 to 60% by weight of Ti, 5 to 20% by weight of W, 5 to 15% by weight of Ta, in which up to 70% of the Ta can be replaced by Nb, and 5 to 25% by weight of Ni and/or Co binder with more than 80 mole %, relative to the above transition elements of carbon and nitrogen. The composition is prepared by grinding, compressing and sintering a solid, powder-form mixture containing (Ti,W,Ta,Nb)C powder, Ti(C,N) powder, and WC powder, each powder having a particle size <1.5 .mu.m, plus Ni powder and/or Co powder. The mixture includes the following ingredients: (a) (Ti,W,Ta,Nb)C with a mean particle size <1.5 .mu.m, this mixed carbide containing 20 to 50% by weight of TiC, 20 to 40% by weight of WC, and 20 to 40% by weight of (Ta, Nb)C; (b) Ti(C,N), with a mean particle size <1.5 .mu.m and an N/(C+N) ratio <0.7; WC with a mean particle size <1.5 .mu.m; and (d) nickel and/or cobalt.

Claims15

Dependent claims

Cermet with a hard material phase containing (Ti,W,Ta/Nb)C and (Ti,W,Ta/Nb)CN, the balance a binder phase with a proportion of

>5% by mass of Co and/or Ni, characterized by a gross composition of 30 to 60% by mass Ti, 5 to 20% by mass W, 5 to 11% by mass Ta which can be replaced up to 70% by Nb, 5 to 25% by mass Ni and/or Co, with more than 80% mole--relative to the abovementioned Ti, W, Ta, and/or Nb, of carbon and nitrogen, which has been prepared from a solid powdery starting mixture with 15 to 45% by mass(Ti,W,Ta)C and/or (Ti,W,Ta,Nb)C, 3 to 15% by mass WC, 5 to 25% by mass Co and/or Ni, the balance Ti(C,N), each with a particle size <1.5.mu. through grinding, pressing and sintering and which has at least 40% of hard material particles in the structure with a core-margin structure with cores of Ti(C,N), N>C and homogeneous marginal zones of (Ti,W,Ta/Nb)C, whereby the proportion of the hard material phase amounts to 95 to 75% by mass.

A process for producing a cermet with a hard material phase containing (Ti,W,Ta/Nb)C, (Ti,W,Ta/Nb)CN, the balance a binder phase with a proportion of

>5% by mass of Co and/or Ni, said cermet having a gross composition of 30 to 60% by mass Ti, 5 to 20% by mass W, 5 to 11% by mass Ta which can be replaced up to 70% by Nb, 5 to 25% by mass Ni and/or Co, with more than 80% mole relative to the abovementioned Ti, W, Ta, and/or Nb of carbon and nitrogen, and which has at least 40% of hard material particles in the structure with a core-margin structure with cores of Ti(C,N) N>C and homogeneous marginal zones of (Ti,W,Ta/Nb)C, whereby the proportion of the hard material phase amounts to 95 to 75% by mass, which comprises the steps of:
(1) grinding a starting mixture which contains the following components:
(a) 15 to 45% by mass (Ti,W,Ta)C with an average particle size of <1.5 .mu.m, whereby this carbide mixture contains 20 to 50% by mass TiC, 20 to 40% by mass WC, and 20 to 40% by mass TaC, whereby the Ta can be replaced up to 70% by mass by Nb;
(b) 3 to 15% by mass WC with an average particle size of <1.5 .mu.m;
(c) 5 to 25% by mass nickel and/or cobalt;
and
(d) the balance Ti(C,N) with an average particle size of <1.5 .mu.m and a proportion of N/(C+N)>0.7, to obtain a ground mixture;
(2) pressing the ground mixture obtained during step (a) into a green compact;
and
(3) sintering the green compact to obtain the cermet.

7 more elements

Dependencies are inferred from the claim text.

Cermet and method of producing it

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Cermet and method of producing it

Life of this patent

Abstract

Claims15