Abstract: A composite sintered compact containing high density boron nitride, which consists of zincblende-type boron nitride, wurtzite-type boron nitride, ceramic material and metal in a specifically limited mixing ratio and has a high abrasion resistance, can be obtained under a relatively mild sintering condition and can be easily worked into a cutting tool.

Abstract: A sintered compact of boron nitride with high density form having high oxidation resistance, water resistance, compressive strength and hardness can be obtained by sintering wurtzite-structured boron nitride together with a boride of titanium, zirconium or hafnium, or with mixtures thereof under a condition of high temperature and high pressure.

Abstract: An apparatus for generating shock waves by means of a supersonic projectile to effect, for example, phase transformation of a substance. A hammer in a cylinder is accelerated by introduction of compressed air into the cylinder, whereby a plunger formed integrally with the hammer at one end thereof is thrust into a hydraulic pressure chamber filled with a liquid and disposed coaxially with the cylinder. Thereupon, a high hydraulic pressure is generated in a hydraulic pressure chamber, and this hydraulic pressure accelerates a piston in a piston chamber connected with the hydraulic pressure chamber. The piston in turn compresses a light gas adiabatically to a high pressure, and a projectile fitted at one end of a barrel is thrust forward under the force of this high-pressure gas.

Abstract: A method for avoiding cracking of the molded body during the decompression step in an isostatic pressing method of molding. The powders to be molded are housed in a shaping rubber mold, are molded under pressure, and the improvement is characterized by supplying forcibly gas between the outer peripheral surface of a molded body or a shaping thin rubber bag where the molded body is housed and the inner peripheral surface of the shaping rubber mold, the gas having a pressure higher than the isostatic pressure applied to the shaping rubber mold at the time when the shaping rubber mold begins to restore to its original state during the decompression step of the method. An apparatus for the said compression molding which is equipped with a specially designed pressure gas inletting device.

Abstract: A method for avoiding cracking of the molded body during the decompression step in an isostatic pressing method of molding. The powders to be molded are housed in a shaping rubber mold, are molded under pressure, and the improvement is characterized by supplying forcibly gas between the outer peripheral surface of a molded body or a shaping thin rubber bag where the molded body is housed and the inner peripheral surface of the shaping rubber mold, the gas having a pressure higher than the isostatic pressure applied to the shaping rubber mold at the time when the shaping rubber mold begins to restore to its original state during the decompression step of the method. An apparatus for the said compression molding which is equipped with a specially designed pressure gas inletting device.