Ngk Insulators, Inc.

Takehiro Kajihara

Hirotsugu Izumiya

Senji Atsumi

Shinichi Miwa

Seiichi Asami

Masayuki Kaneno

Takao Totoki

Masaharu Kajita

Koichiro Maekawa

Toshio Ohashi

Kouichi Imao

Mitsugu Suzuki

A beta-alumina solid electrolyte for use in a sodium-sulfur battery is composed of beta-alumina crystals having a degree of orientation toward the C axis thereof, of 0.2-0.4 and an aspect ratio of 4.0 or less. The beta-alumina solid electrolyte is composed of the beta-alumina crystals having a degree of orientation toward the C axis thereof, of 0.2-0.4 and has such a particle diameter distribution that the average particle diameter is 3 .mu.m or less, the proportion of the particles having a particle diameter of 5 .mu.m or less is 90% or more, and the maximum particle diameter is 300 .mu.m or less. A process for producing a beta-alumina solid electrolyte using an alumina source material, a magnesium source material and a sodium source material, uses a magnesium-aluminum spinel as the magnesium source material and subjects all materials to mixing, granulation, molding and firing to obtain a beta-alumina solid electrolyte without subjecting the materials to calcination. The beta-alumina solid electrolyte has a low electrical resistance and a large strength to internal water pressure and exhibits excellent properties when used as a diaphragm for a sodium-sulfur battery.

Beta-alumina solid electrolyte and process for production thereof

Beta-alumina solid electrolyte

A method of manufacturing silicon nitride sintered bodies comprising the steps of preparing a powder consisting essentially of 100 parts by weight of silicon nitride, 2.about.15 parts by weight of a rare earth element, 0.5.about.15 parts by weight of a Zr compound and 0.3.about.5 parts by weight of SiC, molding the thus prepared powder and firing the resulting molding.

Method of manufacturing high density silicon nitride sintered bodies

A ceramic lid for sealing a semiconductor element and having a sealing surface which is to seal a semiconductor element within a recess of a ceramic package, by heating the recess with glass sealant and hermetically sealing the semiconductor element. The ceramic lid is made of alumina of high purity and to the sealing surface of the ceramic lid is applied a glass sealing aid which is pretreated at a higher temperature than the heating temperature for sealing the semiconductor element, before hermetically sealing the semiconductor element in the ceramic package. A method of manufacturing a ceramic lid for sealing a semiconductor element includes the steps of manufacturing the ceramic lid with alumina of high purity having a sealing surface with the recess of the ceramic package, wherein to the sealing surface of the ceramic lid is applied a glass sealing aid of 5-30 .mu.m in thickness onto a sealing surface of the ceramic lid with the ceramic package. The ceramic lid is heat-treated at a higher temperature than the sealing temperature of the semiconductor element. Thereafter a glass sealant is applied and dried on the glass sealing aid layer, and then calcined at a temperature lower than the airtight sealing temperature of the semiconductor element, thereby removing an organic binder contained in the glass sealant. A semiconductor element is then housed within a recess of the ceramic package and the ceramic lid and a glass sealant are heated to hermetically seal the ceramic lid with the semiconductor element in the recess to the ceramic package.

Ceramic lid for sealing semiconductor element and method of

Silicon nitride sintered bodies including Si.sub.3 N.sub.4 and at least one element selected from Y.sub.2 O.sub.3, MgO, ZrO.sub.2. In the silicon nitride bodies, a J phase solid solution is present in an intergranular phase, which satisfies a relation of 0.65x.ltoreq.y.ltoreq.x+2 wherein y is an amount of J phase solid solution and x is an amount of Y.sub.2 O.sub.3 as an additive.

Silicon nitride sintered bodies

A discharge tube for a high pressure metal vapor discharge lamp is disclosed, which comprises a translucent alumina tubular body, first and second end plates of cermet having a firing shrinkage factor which is less than that of the translucent alumina tubular body, end first and second electrode support members partially embedded in inner sides of the first and second end plates, respectively. The first end plate is fitted to the first end portion of the alumina tubular body and bonded thereto through shrinkage fitting at a shrinkage fitting ratio of the tubular body to the first end plate being from 3 to 6% during a simultaneous sintering of the first end plate to the tubular body and a simultaneous bonding of the first electrode support member to the first end plate through shrinkage fitting at a shrinkage fitting ratio of the first end plate to the first electrode support member being from 4 to 16% when the alumina tubular body is fired to be translucent. The second end plate is fitted to the second opposite end portion of the tubular body and is bonded thereto by means of a frit. When the discharge lamp is in use, the second opposite end portion is located at a vertically higher position than the first opposite end portion. A method of producing such discharge tubes is also disclosed.

Discharge tube for a high pressure metal vapor discharge lamp and a

A ceramic envelope device for a high-pressure metal-vapor discharge lamp, including a translucent ceramic tube, a pair of electrically conducting end caps closing opposite ends of the ceramic tube, and a pair of opposed discharge electrodes each of which is supported at its one end by the corresponding end cap such that the other end of the electrode protrudes from the inner surface of the corresponding end cap in a longitudinally inward direction of the ceramic tube. Each of the end caps is covered at its inner surface with an electrical insulator. The electrical insulator has a protruding portion surrounding a part of the corresponding electrode which protrudes from a radially central portion of the inner surface of the corresponding end cap. The surrounded part of the corresponding electrode is radially spaced from the protruding portion (the electrical insulator).

Ceramic envelope device for high-pressure discharge lamp

Disclosed herein is a discharge tube for a high pressure metal vapor discharge lamp, which discharge tube comprises a translucent alumina tubular body, a lower end plate bonded to one end portion of the alumina tubular body which has an electrode support member inside thereof and is bonded to the alumina tubular body when the alumina tubular body is subjected to the light transmission treatment through firing, another end plate which has an electrode support member inside thereof and is bonded to the other end of the translucent alumina tubular body by means of a frit. This discharge tube is produced by inserting an end plate in which an electrode support member is partially embedded on the inner side thereof into one end portion of a tubular body made of high purity alumina, firing the green or calcined tubular body with the end plate, so that the tubular body is made translucent and simultaneously the end plate is bonded to the tubular body, and attaching another end plate to the other end of the alumina tubular body with the frit.

A ceramic envelope device for a high-pressure metal-vapor discharge lamp, including a translucent ceramic tube, a pair of end caps closing opposite ends of the ceramic tube, and a pair of oppositely located discharge electrodes each of which is supported at a first end by the corresponding end cap such that a second end of the electrode protrudes from an inner surface of the corresponding end cap in the longitudinal direction of the ceramic tube. The end caps are electrically conductive, and completely covered at their inner surfaces with an electrical insulator.

A non-oxidizing firing furnace for ceramic articles, which comprises a furnace chamber filled with a non-oxidizing gas, a conveyor mechanism provided on the floor portion of the furnace chamber and adapted to move the ceramic articles oppositely to a direction in which the non-oxidizing gas is flown through the furnace chamber for firing the ceramic articles; and at least one partition wall with the surface being composed of molybdenum which partition wall is provided at the ceiling portion of the furnace chamber to define a low temperature zone on the inlet side for the ceramic articles and a high temperature zone.

Non-oxidizing atmosphere firing furnace for ceramic articles

A polycrystalline translucent alumina sintered body having high in-line transmission, which is suitable for an envelope for a high pressure vapor discharge lamp, is produced by adding to alumina powder having a purity of more than 99.8% MgO or a compound forming MgO in an amount of 0.01-0.1% by weight calculated as MgO, La.sub.2 O.sub.3 or a compound forming La.sub.2 O.sub.3 in an amount of 0.001-0.05% by weight calculated as La.sub.2 O.sub.3, and Y.sub.2 O.sub.3 or a compound forming Y.sub.2 O.sub.3 in an amount of 0.001-0.05% by weight calculated as Y.sub.2 O.sub.3, thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under vacuum or either atmosphere of hydrogen gas or dissociated ammonia gas under oxygen concentration of 10.sup.-15 -10.sup.-25 atm.

Polycrystalline translucent alumina sintered body, a method for

A polycrystalline translucent alumina sintered body having high in-line transmission, which is suitable for an envelope for a high pressure vapor discharge lamp, is produced by adding to alumina powder having a purity of more than 99.8% MgO or a compound forming MgO in an amount of 0.01-0.1% by weight calculated as MgO, La.sub.2 O.sub.3 or a compound forming La.sub.2 O.sub.3 in an amount of 0.001-0.05% by weight calculated as La.sub.2 O.sub.3, and Y.sub.2 O.sub.3 or a compound forming Y.sub.2 O.sub.3 in an amount of 0.001-0.5% by weight calculated as Y.sub.2 O.sub.3, thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under vacuum or either atmosphere of hydrogen gas or dissociated ammonia gas under oxygen concentration of 10.sup.-15 -10.sup.-25 atm.

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Komaki, Japan

Takehiro Kajihara