Kurosaki Refractories Co., Ltd.

Nobuhiro Sato

Haruyuki Ueno

Yuji Katsura

Takashi Hamamatu

A complex-shaped bonded body of silicon nitride having a high bonding strength of more than 30 kg/mm.sup.2 as flexural strength and continuously homogenous microstructure through the bonded portion can be obtained by the method comprising the following five steps:

Method for bonding ceramics

A shaped body of silicon nitride enjoying high density, ample shrinkage, and outstanding mechanical strength is produced in a desired pattern by a method of preparing a shaped body comprising Si particles and a compound capable of remaining as SiC or C in the form of film on the surface of the Si particles in a non-oxidative atmosphere at a temperature in the range of 900.degree. to 1,400.degree. C., subjecting the shaped body to sintering and shrinkage of not less than 1% in an atmosphere of inert gas at a temperature exceeding 900.degree. C., and not exceeding the softening point of Si, and subsequently subjecting the resultant sintered shaped body to nitriding in a nitriding atmosphere at a pressure exceeding atmospheric pressure and at a temperature in the range of 1,200.degree. to 1,500.degree. C. In another aspect of the present invention, a method for producing a silicon nitride sintered product entails preparing a molded body by adding, to powdery silicon grains, a compound that decomposes under heating to produce H.sub.2 or hydrocarbon compounds such as CH.sub.4 and C.sub.2 H.sub.6 in a temperature range from 500.degree. C. to 1200.degree. C., subjecting the molded body to a heat treatment in a gas atmosphere of a nitriding gas and/or an inert gas, and then chemically converting silicon into silicon nitride in a nitriding gas at a temperature higher than 1200.degree. C.

Method for producing high-density silicon nitride sintered product

Method produces reaction sintered silicon nitride complex shapes. Parent material (moldings of silicon powder-cured resin) and bonding or joint material (silicon powder-uncured resin) are integrally connected by steps of heat-curing the resin in the joint, heating the body thus bonded together to pyrolyze the cured resin and sinter the silicon powder, the pyrolysis gas reducing oxide film on silicon, and sintered parent material and joint material are simultaneously nitrided and integrally connected by continuous silicon nitride.

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Kitakyushu, Japan

Nobuhiro Sato