Abstract: An abrasive grain for use as a grinding material comprising alpha-alumina crystal particles substantially smaller than 0.5 microns, solidly dissolved with at least one of Ti, Mn, V, Ga, Zn and Rh, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 from 4.75892 to 4.76340 angstroms when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and an abrasive grain for a grinding material, comprising alpha-alumina crystal particles substantially less than 0.5 microns, solidly dissolved with at least one of Mg, Ni and Co, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 from 4.75930 to 4.76340 .ANG. when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and further, a grinding wheel and coated cloth manufactured from these abrasive grains.

Abstract: In a semiconductor device such as hybrid IC, thermal heads, etc., a thick film resistor of the semiconductor device contains a boride particle of a metal dispersed in a glass matrix, the particle having a particles size of 0.005 to 0.1 .mu.m. Generation of a thermal stress can be suppressed and the electroconductive particles themselves form isotropic electroconductive passages by such dispersion, and the semiconductor devices can have a distinguished electroconductivity. Preferable boride of a metal is LaB.sub.6, which gives distinguished resistor characteristics.

Abstract: An abrasive grain for use as a grinding material characterized by alpha-corundum crystal particles substantially smaller than 0.5 micron, solidly dissolved with at least one element out of Ti, Mn, V, Ga, Zn and Rh, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 at 4.75892 to 4.76340 angstrom when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and an abrasive grain for a grinding material, characterized by alpha-corundum crystal particles substantially less than 0.5 micron, solidly dissolved with at least one element out of Mg, Ni and Co, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 at 4.75930 to 4.76340 A when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and further, a grindstone and grinding cloth manufactured that these abrasive grains.

Abstract: To simplify propeller shaft supporting structure and to reduce propeller shaft vibration when a viscous coupling and a clutch mechanism are both provided on a propeller shaft of a 4WD vehicle, the power transmission apparatus comprises a housing rotatably supported to receive power; a differential gear disposed on one side of and within the housing; a viscous coupling disposed on the other side of and within the housing; and a clutch for transmitting power from the housing to the differential gear via the viscous coupling when engaged, and transmitting no power from the housing to the differential gear when disengaged.

Abstract: A substrate for hybrid IC which comprises a substrate, a thick film resistor containing glass, formed on the substrate, and a thick film conductor at the terminal of the thick film resistor, where a means for preventing diffusion of the glass from the thick film resistor into the thick film conductor is provided between the thick film resistor and the thick film conductor has a stable resistance as a thick film microresistor and is applied to various uses such as cellular radio communication system.

Abstract: A shoe-and-socket joint, which is incorporated into a swash plate type compressor as a drive force transmitting unit arranged between a rotatable swash plate and each of a plurality of reciprocal pistons, has a shoe provided with a spherically formed contact face having a radius R2 and a spherically formed socket recessed in each of the pistons and having a radius R1, the radius R1 being 20 to 150 microns larger than the radius R2, to provide a clearance between the shoe surface and the surface of the socket into which an oil-containing refrigerant can flow to lubricate the shoe surface and the surface of the socket.

Abstract: A water jacket in the turbo-charger is positioned at the same level or higher than a water jacket in an engine cylinder head. The turbo-charger cooling water circulation passageway includes a water volume or tank positioned at a level higher than the turbo-charger cooling portion, and the volume or tank is connected to a cooling water reservoir tank via a pressure relief valve which is opened when pressure in the volume or tank exceeds a predetermined value to supply cooling water to the volume or tank.

Abstract: In an air jet loom including a weft inserting apparatus constructed in accordance with the principles of this invention, a weft is inserted into a warp shed by being ejected, together with compressed air, from an ejection nozzle of the weft inserting apparatus. When the weft passes through a weft guide passage in the ejection nozzle, it is adapted to deviate from the center or axis of at least a portion of the weft guide passage since an air discharge hole is provided in the ejection nozzle in fluid communication with the atmosphere so as to open into said portion of the weft guide passage.

Abstract: In the manufacture of a wiring board, or a heat discharge plates and the like in the field of the electronics, composite materials consisting of substrates and organic polymeric materials and epoxy resin, as well as ceramic materials such as alumina plates, have heretofore been used as substrates of printed wiring boards and heat sinks. These substrate materials, however, are defective in that, because of a low thermal conductivity and an insufficient heat radiation.A highly thermal conductive and electrical insulating substrate of the invention comprises a highly thermal conductive metal plate, such as aluminum, and a film formed thereon, said film being composed of a dispersion of metal oxide particles having a shape factor, of 1 to 1.4, and also, having a polyhedral shape including smooth surfaces in an adhesive organic polymer. The space factor is an average value of the long diameter/short diameter ratio of the metal oxide particles.

Abstract: A method for preparing corundum particles by a hydrothermal process which comprises adding fine particles of corundum to a starting alumina hydrate, and subjecting the resulting mixture to a hydrothermal reaction or treatment, the alumina in the alumina hydrate being deposited on the surfaces of the fine corundum particles while suppressing formation of new corundum crystal nuclei.