Abstract: A heat conductive aluminum nitride sintered body contains 100 parts by weight of aluminum nitride, at least 0.005 parts by weight and not more than 0.5 parts by weight of carbon, at least 0.01 parts by weight and not more than 15 parts by weight of a rare earth aluminum oxide in terms of the simple substance of a rare earth element, and at least 0.01 parts by weight and not more than 15 parts by weight of at least one element selected from a group of compounds containing elements belonging to the groups IVB, VB and VIB of the periodic table in terms of the simple substance of the element. Heat conductivity of the aluminum nitride sintered body is at least 100 W/m.multidot.K and not more than 270 W/m.multidot.K at the ordinary temperature. According to a method of preparing such an aluminum nitride sintered body, at least 0.01 parts by weight and not more than 5 parts by weight of carbon, at least 0.01 parts by weight and not more than 15 parts by weight of an oxide of a rare earth element, and at least 0.

Abstract: The present invention provides a sintered body of aluminum nitride comprising (i) aluminum nitride as a main component and (ii) at least one component selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Nd, Ho, Ti and compounds thereof in the total amounts of not greater than 1.0 wt. % and not less than 0.01 wt. % in terms of elements on the basis of sintered body, the sintered body being colored and having a thermal conductivity of at least 150 W/mK. The sintered body is useful for the preparation of circuit boards having printed circuits thereon and highly heat-releasing ceramic packages for semiconductive devices.

Abstract: A composite bearing structure can withstand high speed rotation has first, second and third bearing components. The first bearing component supports a radial impact force applied to a rotator during rotation, and is made of an inner ring (1) and an outer ring (2) of silicon nitride ceramic sintered bodies. The second bearing component supports an axial load applied to the rotator while maintaining a required clearance between itself and the rotator and is made of two permanent magnets (12, 13) positioned thrustdirectionally opposite to each other. The third bearing component maintains a radial rotational accuracy of the rotator, and is made of a radial dynamic pressure producing groove (5) provided on a cylindrical surface of the inner ring (1).

Abstract: The present invention relates to a silicon nitride sintered body [wherein the composition of Si.sub.3 N.sub.4 -first aid (Y.sub.2 O.sub.3 +MgO)-second aid (at least one of Al.sub.2 O.sub.3 and AlN)] falls within a range defined by lines joining points A, B, C and D in FIG. 1, the crystal phase of the sintered body contains both .alpha.-Si.sub.3 N.sub.4 and .beta.'-sialon, and the relative density is 98% or more. This sintered body is produced by subjecting a green compact of the above-described source to primary sintering in a nitrogen gas atmosphere at 1300 to 1700.degree. C. so that the relative density reaches 96% or more, and the precipitation ratio of the .alpha.-Si.sub.3 N.sub.4 crystal phases to the .beta.'-sialon crystal phase in the sintered body is in the range of from 40:60 to 80:20; and then subjecting the primary sintered body to secondary sintering in a nitrogen gas atmosphere at 1300 to 1700.degree. C. so that the relative density reaches 98% or more.

Abstract: An aluminum nitride sintered body characterized by comprising aluminum nitride as the main component, containing a titanium compound, and having a black color, a transmittance of 10% or less with the light having a wavelength in the range of from 500 to 650 nm and a heat conductivity of 120 W/m.multidot.K or more. The sintered body is produced by adding 0.05 to 5% by weight, in terms of Ti, of a titanium compound and a sintering aid compound and, if necessary, a compound capable of forming carbon after being thermally decomposed to an aluminum nitride powder, molding the mixture, heating the molding in vacuo, air or a nitrogen gas, a hydrogen gas or an atmosphere comprising a mixture of these gases until the residual carbon content is reduced to 2.0% by weight or less, and sintering the heat-treated mixture in a nonoxidizing atmosphere containing nitrogen at 1600.degree. C. or above. The titanium compound is Ti.sub.n O.sub.2n-1 or a solid solution comprising Ti.sub.n O.sub.

Abstract: The present invention provides a sintered body of aluminum nitride comprising (i) aluminum nitride as a main component and (ii) at least one component selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Nd, Ho, Ti, and compounds thereof in the total amounts of not greater than 1.0 wt. % and not less than 0.01 wt. % in terms of elements on the basis of sintered body, the sintered body being colored and having a thermal conductivity of at least 150 W/mK. The sintered body is useful for the preparation of circuit boards having printed circuits thereon and highly heat-releasing ceramic packages for semiconductive devices.

Abstract: A ceramic compact having excellent high temperature strength, toughness and reliability, which comprises a matrix preferably composed predominantly of silicon nitride and ceramic fibers uniformly dispersed in the matrix and orientated in a desired direction, said matrix and fibers being closely bonded by sintering. This compact is produced, for example, by preparing a shaped body of silicon, for example, in which ceramic fibers are uniformly dispersed by centrifugal casting and then heating and nitriding the shaped body in a nitrogen atmosphere to form a fiber-reinforced silicon nitride sintered compact. The ceramic fibers may include such fibers as aluminum oxide or silicon carbide fibers. Sintering assistants, such as silicon nitride, may be used to prepare the sintered compact.

Abstract: A high-strength silicon nitride sintered body having a flexural strength of 100 kg/mm.sup.2 or higher and a process for producing the same are disclosed, the sintered body comprising not less than 90% by weight of a single crystalline phase of silicon aluminum oxynitride (Si.sub.6-z Al.sub.2 O.sub.z N.sub.8-z, wherein z is a number of from 0 to 4.2) having an average longer diameter of not more than 5 .mu.

Abstract: There is provided a process for the production of a sintered article which comprises steps ofshaping a raw material powder comprising silicon nitride,thermally treating a shaped article in a non-oxidizing atmosphere at a temperature of 1300.degree. to 1650.degree. C. for at least 2 hours to form .beta.-silicon nitride of not less than 85% calculated from X-ray diffraction patterns and to increase a relative density of the article to not less than 80%, preferably to 80 to 85 %, andsintering the thermally treated article at a temperature of 1700.degree. to 2000.degree. C.

Abstract: The present invention provides a sintered body of aluminum nitride comprising (i) aluminum nitride as a main component and (ii) at least one component selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Nd, Ho, Ti and compounds thereof in the total amounts of not greater than 1.0 wt.% and not less than 0.01 wt.% in terms of elements on the basis of sintered body, the sintered body being colored and having a thermal conductivity of at least 150 W/mK. The sintered body is useful for the preparation of circuit boards having printed circuits thereon and highly heat-releasing ceramic packages for semiconductive devices.

Abstract: For evaluating mechanical properties of ceramics such as silicon nitride in a nondestructive manner, a specific heat of ceramic test samples to be evaluated is measured at a temperature not higher than room temperature. A comparison is made between a measured value of the specific heat of the test sample and a known value of a specific heat of a ceramic reference sample at the same temperature not higher than room temperature. The comparison, permits making conclusions regarding the mechanical properties of the ceramic test samples based on the known mechanical properties of the ceramic reference sample. The creep strength is given as one example of the mechanical properties that may be ascertained by a nondestructive inspection that may be part of a production line, whereby the mechanical properties of the individual ceramic products may be guaranteed in practice.

Abstract: The present invention relates to a silicon nitride sintered body [wherein the composition of Si.sub.3 N.sub.4 -first aid (Y.sub.2 O.sub.3 +MgO)-second aid (at least one of Al.sub.2 O.sub.3 and AlN)] falls within a range defined by lines joining points A, B, C and D in FIG. 1, the crystal phase of the sintered body contains both .alpha.-Si.sub.3 N.sub.4 and .beta.'-sialon, and the relative density is 98% or more. This sintered body is produced by subjecting a green compact of the above-described source to primary sintering in a nitrogen gas atmosphere at 1300.degree. to 1700.degree. C. so that the relative density reaches 96% or more, and the precipitation ratio of the .alpha.-Si.sub.3 N.sub.4 crystal phases to the .beta.'-sialon crystal phase in the sintered body is in the range of from 40:60 to 80:20; and then subjecting the primary sintered body to secondary sintering in a nitrogen gas atmosphere at 1300.degree. to 1700.degree. C. so that the relative density reaches 98% or more.

Abstract: A ceramics composite material containing crystallized glass as the matrix and fibers or whiskers of ceramics as a reinforcement material, is obtained by melting original glass to form crystallized glass, compounding the same with fibers or whiskers of oxide ceramics and thereafter crystallizing the original glass. This ceramics composite material does not form any voids and can easily contain at least 50 volume percent of the reinforcement material, whereby a good mechanical strength and fracture toughness are achieved. In the compounding step, the content of the reinforcement can be further increased by forcing out any excess part of the original glass from the reinforcement material by applying pressure to a substance obtained by mixing the original glass with the reinforcement. Further, the ceramics composite material can be efficiently formed into a desired configuration by heating because the original glass flows viscously.

Abstract: Disclosed is a silicon nitride sintered body produced by subjecting a green compact of a mixed powder composed of 1) a silicon nitride powder having a percentage .alpha. crystallization of 93% or more and a mean grain diameter of 0.7 .mu.m or less and 2) 5 to 15% by weight in total of a first sintering aid selected from among rare earth element, yttrium oxide and lanthanide oxides and a second sintering aid consisting of aluminum oxide or nitride and at least one selected from among oxides and nitrides of Mg, Ca and Li, to primary sintering in a nitrogen gas atmosphere under a pressure of 1.1 atm or less at 1500.degree. to 1700.degree. C.; and subjecting the sintered body to secondary sintering in a nitrogen gas atmosphere under a pressure of 10 atm or more at the primary sintering temperature or below, thereby giving a sintered body wherein the relative density of the sintered body is 99% or more and the precipitation ratio of an .alpha.-Si.sub.3 N.sub.4 (including .beta.

Abstract: An AlN sintered body which has a color within the range of gray to black and a thermal conductivity within the range of 100 to 270 W/m.multidot.K at room temperature. Such a body is useful as an electronic material and a method of preparing the same. The AlN sintered body contains 100 parts by weight of AlN, 0.005 to 0.5 parts by weight of carbon, not more than 1 part by weight of a boron compound in terms of the simple substance of boron, 0.01 to 15 parts by weight of a rare earth aluminum oxide in terms of the simple substance of the rare earth element, and 0.01 to 15 parts by weight of a compound containing an element belonging to the group IVB of the periodic table in terms of the simple substance of the element. This AlN sintered body is obtained by shaping a mixture of the above components into a prescribed configuration and thereafter firing the as-formed compact in a non-oxidizing atmosphere containing at least 10 percent by volume of nitrogen, at a temperature of 1500.degree. to 2100.degree. C.

Abstract: An SiC whisker-reinforced Si.sub.3 N.sub.4 composite material comprising a sintered body of an Si.sub.3 N.sub.4 matrix having dispersed therein SiC whiskers, wherein said SiC whiskers are uniaxially orientated; a process for producing an SiC whisker-reinforced Si.sub.3 N.sub.4 composite material which comprises mixing (1) SiC whiskers having a coating comprising an oxide of at least one metallic element selected from the group consisting of Be, Mg, Ca, Sr, and Ba of the group 2A; Sc, Y, and La of the group 3A; Ti, Zr, and Hf of the group 4A; and Li, Al, and Si with (2) Si.sub.3 N.sub.

Abstract: An aluminum nitride sintered body is mainly composed of aluminum nitride, contains 0.01 to 1.0 percent by weight of a rare earth element and 0.001 to 0.5 percent by weight of oxygen, and has thermal conductivity of at least 180 W/mK. According to a method of manufacturing such an aluminum nitride sintered body, aluminum nitride powder (201) is first prepared. At least one compound (203) containing a rare earth element is added to the aluminum nitride powder (201) to contain 0.01 to 1.0 percent by weight, in rare earth element conversion, of the compound, to be homogeneously mixed with each other. A formed body obtained by forming such mixed powder is sintered in a non-oxidizing atmosphere containing nitrogen at a temperature of 1500 to 2200.degree. C.

Abstract: An aluminum nitride sintered body mainly composed of aluminum nitride, contains 0.01 to 1.0 percent by weight of a rare earth element and 0.001 to 0.5 percent by weight of oxygen. Such a body has a thermal conductivity of at least 180 W/mK. For manufacturing such an aluminum nitride sintered body, aluminum nitride powder (201) is first prepared. At least one compound (203) containing a rare earth element is added to the aluminum nitride powder (201) to contain 0.01 to 1.0 percent by weight, in rare earth element conversion, of the compound. The ingredients are homogeneously mixed with each other. A green body is formed of the mixed powder and sintered at a temperature of 1500.degree. to 2200.degree. C. in a non-oxidizing atmosphere containing nitrogen.

Abstract: A connection structure between lead frames and a base plate of aluminum nitride, to be applied as a connection structure between components of a semiconductor apparatus, has a base plate made of a sintered body of aluminum nitride on which a semiconductor device is to be mounted. The lead frames are made of iron alloy containing nickel in 29 wt. % and cobalt in 17 wt. %. A silver solder is used for joining the base plate and the lead frames. A surface of the lead frame to be joined to the base plate is clad with a stress relief layer of oxygen-free copper of a high plastic deformability to relieve, by its plastic deformation, a thermal stress caused by a difference between a thermal expansion coefficient of the aluminum nitride base plate and that of the lead frame in a cooling process at the time of soldering. Preferably, only a portion of each lead frame to be joined to the base plate comprises an inner layer of an iron alloy containing 29 wt. % of nickel and 17 wt.

Abstract: A ceramic compact having a more excellent high temperature strength, toughness and reliability, which comprises a silicon nitride matrix and ceramic fibers uniformly dispersed in the matrix and orientated in a desired direction, said matrix and fibers being closely bonded by sintering, is provided. This compact is produced, for example, by preparing a shaped body of silicon in which ceramic fibers are uniformly dispersed and then bearing and nitriding the shaped body in a nitrogen atmosphere to form a fiber-reinforced silicon nitride sintered compact.