Hitachi, Ltd.

Kousuke Nakamura

Yasuo Matsushita

Mitsuru Ura

Yukio Takeda

Satoru Ogihara

Kunihiro Maeda

Yoshiyuki Yasutomi

Tadamichi Asai

Tokio Ohkoshi

Masahisa Sobue

Hideki Kita

Yukio Takahashi

Satoshi Shimada

Shinichi Itoh

Kazuji Yamada

Hisanori Okamura

Fumiyuki Kobayashi

Kunio Miyazaki

Hiroaki Hachino

Yasutoshi Kurihara

Akio Chiba

Koji Harada

Michitaka Shimazoe

Tomio Yasuda

Hirosi Akiyama

Tetuo Kosugi

Yukio Okoshi

Mutuo Kamoshita

Tokio Okoshi

Disclosed is a ceramic composite which comprises particles of at least one inorganic compound selected from the group consisting of a carbide, a nitride, an oxide, a boride, a silicide and an oxy-nitride and particles and whiskers of Si.sub.3 N.sub.4, Si.sub.2 N.sub.2 O or SiO.sub.2. This ceramic composite is small in volume change on sintering, and provides heat resistance. In addition, the composite can absorb thermal shock by its voids. It can be used in association with ceramic heaters, current collectors, commutators for starter motors and alternators, and in other areas.

Process for producing ceramic compositions

Ceramic composite and process for production thereof

Composite ceramic materials and a method of the same are disclosed, in which a ceramic material mainly containing silicon nitride, and at least one compound selected from a group consisting of nitrides, carbides, borides, silicides, oxides and oxynitrides of elements belonging to IIIa, IIIb, IVa, IBb, Va, VIa and VIII are combined to form a sintered body, and particles and whiskers of the ceramic material and compound are interlocked with each other and fixed so that the sintered body has a porosity of 5 to 30%. In the above composite ceramics, the particle of the compound are coupled with each other through the whisker or particle of the ceramic material. Accordingly, the composite ceramics are small in charge rate of size due to sintering, and are excellent in tenacity, heat resisting property and thermal shock resisting property. Further, the resistivity of the sintered body can be varied by changing the mixture ratio of ceramic material and compound.

Composite ceramics and method of making the same

The nuclear fusion reactor of the present invention presents a new vacuum vessel for enclosing plasma particles where a reactor wall exposed to the above plasma particles has a piled structure. A plurality of heat-resisting ceramic tiles are metallurgically bonded to a metal-base body having a cooling means through a brazing material. The ceramic tiles are preferably composed of sintered silicon carbide of high density and containing a little beryllium oxide between the boundaries of crystal grains.

Nuclear fusion reactor

A semiconductor device with a semiconductor element encased in a hollow ceramic package. The portion of the package at which the semiconductor element is disposed is formed from SiC admixed with Be or a compound of Be.

Ceramic packaged semiconductor device

A semi-conductor device comprising sintered aluminum nitride having a high thermal conductivity, which comprises at least 65% by weight of aluminum nitride, and at least one of beryllium, a beryllium compound, lithium and a lithium compound.

Sintered aluminum nitride semi-conductor device

Disclosed are semiconductor devices in which an electrical insulating substrate is made of a sintered silicon carbide body having thermal conductivity of at least 0.4 cal/cm.multidot.sec.multidot..degree.C. at 25.degree. C., electrical resistivity of at least 10.sup.7 ohm.multidot.cm at 25.degree. C. and coefficient of thermal expansion of 3.3.about.4.times.10.sup.-6 /.degree.C. at 25.degree. C. to 300.degree. C.

Semiconductor device having electrically insulating substrate of SiC

A silicon carbide sintered body comprising silicon carbide as principal constituent, a first component for providing electrical insulating properties to said silicon carbide, said first component comprising at least one of metallic beryllium, beryllium compounds, boron and boron compounds and contained in a total amount of 0.01 to 3.5% by weight calculated as metal, and a second component which can further promote said silicon carbide sinterability provided by said first component and which does not diffuse easily in the particles of said silicon carbide, said second component comprising at least one substance selected from the Group I elements exclusive of hydrogen and francium, Group II elements exclusive of beryllium, radium and mercury, Group III elements exclusive of boron and aluminum, Group IV elements exclusive of carbon, Group V elements, Group VIa elements, Group VIIa elements Group VIII elements exclusive of iron, and compounds thereof, and contained in a total amount of 0.01 to 10% by weight, with the remainder substantially comprising silicon carbide. This silicon carbide sintered body has an electrical resistivity of 10.sup.7 .OMEGA..cm or above at room temperature and is also excellent in electrical insulating properties and can be advantageously used as substrates for semiconductor devices, etc.

Electrically insulating silicon carbide sintered body

An electrically conductive sintered ceramics of the present invention comprises, as the main ingredients thereof, (a) silicon carbide, (b) an inorganic compound which exhibits a positive resistance-temperature coefficient, and preferably (c) a sintering assistant. The electrically conductive sintered ceramics obtained exhibits a positive resistance-temperature coefficient as a whole. A ceramic heater of the invention makes use of the electrically conductive sintered ceramics in an electrically conductive portion thereof. A sintered product which exhibits a positive resistance-temperature coefficient helps to prevent the occurrence of thermal runaway or thermal destruction.

Electrically conductive sintered ceramics and ceramic heaters

Sintered aluminum nitride having a high thermal conductivity, which comprises at least 65% by weight of aluminum nitride, and at least one of beryllium, a beryllium compound, lithium and a lithium compound, and a semi-conductor device using the same.

Sintered aluminum nitride and semi-conductor device using the same

Electroconductive ceramic materials with high density, high mechanical strength, high endurance to repeated current supply and excellent thermal shock resistance can be obtained by mixing 5 to 70 parts by weight of Al.sub.2 O.sub.3 or alumina ceramic materials containing 95% by weight or more of Al.sub.2 O.sub.3 and 30 to 95 parts by weight of at least one electroconductive material selected from of ZrB.sub.2, ZrC, ZrN, ZrSi.sub.2, TaB.sub.2, TaC, TaN, TaSi.sub.2, TiB.sub.2, TiC, TiN, Mo.sub.2 B.sub.5 and MoSi.sub.2 adding a molding binder, molding the mixture and sintering the molded mixture. The electroconductive ceramic is usable for heaters, glow plug heaters, electrical gas ignitors, kerosine gasifying burners, and electrodes or conductors for water processing or dialysis.

Electroconductive ceramics

A semiconductor device with a semiconductor element encased in a hollow ceramic package. The portion of the package at which the semiconductor element is disposed is formed from a SiC-based substrate containing Be or a compound of Be with a thin SiO.sub.2 layer being capable of reacting with glass provided thereon and with a glass layer or a thin film circuit on the SiO.sub.2 layer.

A high-temperature thermistor comprising, a polycrystalline sintered body consisting essentially of 0.1-8 weight percents of at least one kind selected from the group consisting of Be, BeO, Be.sub.2 C, B, BN, B.sub.2 O.sub.3 and B.sub.4 C which weight percents are calculated as the amount of only Be or B single substance from net amount, the balance SiC, and the inevitable impurities having not more than 2 weight percents of SiO.sub.2, not more than 0.1 weight percent of Al, not more than 0.2 weight percents of Fe, not more than 1 weight percent of Si, and not more than 0.4 weights percents of free carbon, a pair of electrode provided on the surfaces of the sintered body, and lead wires each connected to the respective electrodes, and a method of producing same.

High temperature thermistor

From 0.1 to 3.5% by weight of beryllium oxide powder, calculated as beryllium, is added to silicon carbide powder containing up to 0.1% by weight of aluminum, up to 0.1% by weight of boron and up to 0.4% by weight of free carbon, and the mixed powder is pressure-molded. The resulting molded article is heated to a temperature of 1,850.degree. C. to 2,500.degree. C. till there is obtained a sintered body having at least 90% relative density of silicon carbide. Thus, the sintered body having thermal conductivity of at least 0.4 cal/cm.sec..degree. C. at 25.degree. C., electrical resistivity of at least 10.sup.7 Ohm.cm at 25.degree. C. and coefficient of thermal expansion of 3.3.about.4.times.10.sup.-6 /.degree.C. at 25.degree. C. to 300.degree. C. can be obtained.

Electrically insulating substrate and a method of making such a substrate

In a semiconductor device, an active element is mounted on a supporter made of silicon carbide SiC. Since the thermal expansion coefficient of SiC is nearly equal to that of the semiconductor element, the integration of the element and the supporter will not give rise to thermal stresses in the element. Since silicon carbide has high degrees of thermal dissipation and conduction, the supporter of SiC can effectively dissipate heat generated in the semiconductor element. And since SiC has a high electrical conductivity and a high mechanical strength and is also light, it can be used as electrodes for the semiconductor element.

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Hitachi, Japan

Kousuke Nakamura