Toshiba Tungaloy Co., Ltd.

Keiichi Kobori

Mitsuo Ueki

Takeshi Saitoh

Hisashi Suzuki

Tuyoshi Saito

Kozo Kitamura

Ko Sasaki

Yasuro Taniguchi

A surface refined sintered alloy with a burnt surface, comprising 75 to 95% by weight of a hard phase containing Ti, C and N as the essential components and otherwise comprising at least one of Zr, Hf, V, Nb, Ta, Cr, Mo and W and the balance of the alloy comprising a binder phase composed mainly of Co and/or Ni and inevitable impurities, wherein the sintered alloy satisfies at least two conditions selected from the group consisting of the following (1) to (3):

Coated surface refined sintered alloy

There are disclosed a high strength nitrogen-containing cermet which comprises 7 to 20% by weight of a binder phase composed mainly of Co and/or Ni, with the balance being a hard phase composed mainly of TiC, TiN and/or Ti(C,N) and inevitable impurities, wherein the hard phase comprises 35 to 59% by weight of Ti, 9 to 29% by weight of W, 0.4 to 3.5% by weight of Mo, 4 to 24% by weight of at least one of Ta, Nb, V and Zr, 5.5 to 9.5% by weight of N and 4.5 to 12% by weight of C; and a process for preparing the same which comprises via the formulating, mixing, drying, molding and sintering steps of Co and/or Ni powder, at least one powder of TiC, Ti(C,N) and TiN, WC powder, Mo and/or Mo.sub.2 C, and at least one powder of carbides of Ta, Nb, V and Zr, wherein the sintering step is carried out by elevating the temperature up to 1350.degree. C. in vacuum, with the nitrogen atmosphere being made 1 torr at 1350.degree. C., increasing gradually the partial nitrogen pressure along with temperature elevation from 1350.degree. C. to the sintering temperature, with the nitrogen atmosphere being made 5 torr at the sintering temperature.

High strength nitrogen-containing cermet and process for preparation

There are disclosed a surface sintered alloy with a burnt surface, comprising 75 to 95% by weight of a hard phase containing Ti, C and N as the essential components and otherwise comprising at least one of Zr, Hf, V, Nb, Ta, Cr, Mo and W and the balance of the alloy comprising a binder phase composed mainly of Co and/or Ni and inevitable impurities, wherein the sintered alloy satisfies at least one condition selected from the group consisting of the following (1) to (3):

Surface refined sintered alloy and process for producing the same and

There are disclosed a surface refined sintered alloy body which comprises a hard phase containing at least one selected from the group consissting of carbides, carbonitrides, carbooxides, carbonitrooxides of the metals of the groups 4a, 5a and 6a of the periodic table and a binding phase containing at least one selected from iron group metals, characterized in that the concentration of the binding phase in the surface layer (of from 10 .mu.m to 500 .mu.m from the surface of the sintered alloy) is highest at the outermost surface thereof and approaches the concentration of the inner portion, the concentration of the binding phase decreasing from the outermost surface to a point at least 5 .mu.m from the surface; and a method for making the same by applying decarburization treatment at the surface of the sintered alloy at temperatures within the solid-liquid co-existing region of the binding phase after sintering or in the process of sintering.

Growing community of inventors

Kawasaki, Japan

Keiichi Kobori