Sumitomo Electric Industries, Limited

Masao Maruyama

Atsushi Seki

Yoshihiko Doi

Yoshihiro Minato

Kotaro Hagiwara

Minori Shirane

Masayoshi Yatabe

Toshikazu Hirayama

Hiroshi Nakagaki

Yasushi Miyawaki

Hard alloy and its manufacturing method

An alloy tool of hard metal has a working part and a non-working part. The working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase and an iron family metal as a basis metal of the binder phase. The working part includes a region for working a work piece. The non-working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase of the non-working part and of an iron family metal as a basis metal of the binder phase of the non-working part. A diffused junction between the working and non-working parts bonds the two parts together. The non-working part has a higher thermal expansion coefficient than the working part, whereby the non-working part, through the diffused junction, applies a residual compressive stress to the working part for an improved tool strength.

Alloy tool of hard metal

A sintered hard metal having superior toughness and superior hardness may be used for micro-drills, tools and wear resistant parts. The metal is a cemented carbide WC formed from tungsten carbide WC as the base alloy and containing 4 to 20 percent by weight of vanadium carbide VC or zirconium nitride. Its micro-structure is that the WC or WC-VC particles are 0.6.mu. or less, its Rockwell Hardness HRA is at least 91.5 and its transverse rupture strength is at least 350 kg/mm.sup.2.

Sintered hard metal having superior toughness

The present invention relates to a sintering furnace for powder metallurgy of cemented carbides, cermets and ceramics, which comprises a main furnace body, a heating chamber provided in the main body, a table having a moving means for carrying a workpiece in or out of the heating chamber and a means for cooling the interior of the furnace with a heat exchanger fitted to the exterior of the main furnace body, and a method for the sintering and heat treatment of cemented carbides in the sintering furnace as claimed in claim 1, which comprises sintering cemented carbides and cooling rapidly at a cooling rate of at least 30.degree. C./min from the sintering temperature being at least a temperature at which a liquid phase appears to at most 1000.degree. C. by the use of an inert gas as a coolant.

Sintering furnace for powder metallurgy

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Itami, Japan

Masao Maruyama