Abstract: The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi.sub.2 O.sub.3. The mix is hot-pressed to form a compact at temperatures below 850.degree. C. and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.

Abstract: A method is disclosed of densifying a silicon nitride comprising compact having 5-17% by weight yttrium silicon oxynitride and having a density of 2.0-2.6 gm/cm.sup.3. The method comprises (a) partially sintering the compact at a temperature of 3000.degree.-3200.degree. F. for a period of 0.5-72 hours to form a semidense body with a density of 2.9-3.15 gm/cm.sup.3, and (b) hot pressing a stacked assembly of said bodies in the hot zone of a hot pressing cavity to form fully dense anisotropic products, each body being separated from the other within the assembly by a distance no greater than 0.03 inch, and the stacked assembly occupying substantially the entire length of the hot zone of the hot pressing cavity.

Abstract: Disclosed is a method for manufacturing an object of silicon nitride. In the method, a body preformed from silicon nitride is surrounded with a casing which is permeable to gas. Upon heating, the casing is transformed into a layer which is impermeable to a pressure medium which is used during isostatic pressing of the preformed body while a pressure outside the casing is maintained which is at least as high as the pressure of the gas which is present in the pores of the preformed product. After the casing has been made impermeable to the pressure medium and the preformed body has been enclosed therein, the isostatic pressing is carried out while the body is simultaneously sintered.

Abstract: The invention is a shaped article of boron nitride having a density of at least 95% of the theoretical density which consists of polycrystalline hexagonal boron nitride in the form of a homogeneous isotropic microstructure and which has been manufactured from pure boron nitride powder without the concomitant use of sintering aids by isostatic hot-pressing in a vacuum-tight casing at temperatures of from about 1200.degree. to 1500.degree. C. under a pressure of from about 50 to 300 MPa. Boron nitride powders having a free boric oxide content of not more than 1.0% by weight and having a specific surface area of from 5 to 30 m.sup.2 /g are used as starting material. The powders either are filled into prefabricated casings consisting of steel or glass and densified by vibration or are preshaped to form green bodies having pores open to the surface and then placed in prefabricated casings or coated with a material which forms a vacuum-tight casing.

Abstract: In a sodium sulphur cell, improved protection of a cathode current collector is obtained by isostatically pressing graphite foil or flakes onto the surface of the collector, which surface is preferably roughened or coated with an intermediate conductive layer such as a nickel-chromium alloy or a conductive carbide providing a rough surface.

Abstract: A method is disclosed for hot pressing agglomerated materials in a pressing assembly having walls which can be reactive with the material to be pressed under the environmental, temperature, and pressure conditions to be experienced by the material at the interface with the pressing assembly walls. After a plurality of generally flat stackable billets (10-20) of the powdered material are formed and stacked in a pressing assembly (21) in a predetermined aligned order, a barrier wall (30) is interposed between the interface of the billets and pressing assembly along at least a zone (26) in which a temperature of 1600.degree.-1750.degree. C. and a pressure of at least 3000 psi will be experienced at the interface during hot pressing. The billets are then hot pressed to a desirable density and removed, leaving the assembly walls in a substantially unreacted condition.

Abstract: A method of making a heat fused silicon nitride comprising object is disclosed. A series of measured powder shots are containerized to be carried in the container between the nitriding and heat fusing steps. The containerization comprises lining the internal wall of a graphitic sleeve, treated for inertness, with a refractory metal foil essentially impervious to migration of carbon ions and having a thickness of 0.2 inches or less. A series of measured shots, of a powder mixture of silicon and oxygen carrying agents, is inserted into the assembly, each shot being separated by an inert spacer. The assembly is subjected to a nitriding treatment and subsequently hot pressed/or sintered.

Abstract: Polycrystalline ceramic scintillators are prepared by a vacuum hot-pressing method. The process includes pressing a multicomponent powder at high temperature under vacuum. Following a holding period, the pressure and temperature are increased and maintained for a predetermined length of time. The finished scintillator includes Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, and one or more of Eu.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Pr.sub.2 O.sub.3, and Tb.sub.2 O.sub.3 rare earth activator oxides. At least one of the oxides of elements Zr, Th, and Ta is included as a transparency promoting densifying agent. At least one of CaO and SrO may be included as a light output restorer.

Abstract: A process improvement is disclosed for making compacts containing diamond which reduces crystal flaws within the diamond. This is accomplished by isolating the single diamond crystals in an compressible matrix before exposing the sample to sintering conditions. One method for doing this (described with reference to FIG. 1) is embedding the diamond 14 in a mixture 16 of graphite and diamond fines. This mixture is disposed between two graphite discs 18 and 19 and two cobalt discs 22 and 23. This sub-assembly is contained within zirconium cup 10 on top of which is placed zirconium disc 12 and exposed to high pressure-high temperature sintering conditions.

Abstract: In the manufacture of sintered silicon nitride articles by hot isostatic pressing, multiple silicon nitride parts are encapsulated within a single capsule for the pressing operation. Suitable spacers placed between the parts ease separation thereof after sintering.

Abstract: In the manufacture of sintered silicon nitride articles by hot isostatic pressing, silicon nitride preforms are assembled in a stack with spacers between the preforms. A plurality of such stacks are inserted in a glass tube closed at one end. The glass is melted around each stack to encapsulate each stack in a single sealed capsule.

Abstract: In the manufacture of sintered silicon nitride articles by hot isostatic pressing, silicon nitride preforms are assembled in a stack with spacers between the preforms. The stack is completely enveloped in refractory metal foil and then encapsulated within a single capsule for the pressing operation.

Abstract: A method for heating a riser of a molten refractory material in which after a heat molten refractory material is poured into a mold, a melt of the molten refractory material at an upper portion of the mold is directly subjected to induction heating by conducting an electric current by application of an AC voltage at a frequency of from 50 to 1,000 KHz to an induction coil with at least 2 windings around the riser portion containing said melt without induction heating the upper portion of the mold.

Abstract: A temperature sensitive element comprises fine grain powders which consist of a spin reorientation type ferromagnetic material having a transition temperature range, below which transition temperature range the easy direction of magnetization of the spin reorientation type ferromagnetic material is predetermined in one crystallographic direction thereof and above which transition temperature range the easy direction of magnetization is a predetermined other direction perpendicular to the predetermined one crystallographic direction. The temperature sensitive element is produced by compacting the fine grain powders at a temperature higher than the transition temperature range. According to the present invention, it is possible to use a polycrystalline rare earth cobalt alloy material in the field where low Curie point ferrite has been used or where bimetals have been used for a thermal valve or a temperature controlling device.

Abstract: Bodies of silicon nitride are produced by enclosing a silicon nitride powder in a gas-tight glass casing and subjecting the casing to isostatic pressure using gas as a pressure medium at a temperature of at least 1600.degree. C. and a pressure of at least 100 MPa. The casing is a glass having a high softening point. The casing is evacuated and sealed before compressing. The product may be pre-formed by isostatic compacting at a pressure of at least 100 MPa at a temperature considerably below the sintering temperature. The casing is cooled at a rate of at most 1000.degree. C. per hour and at a pressure of not over 10 MPa.

Abstract: To produce ceramic lithium nitride as solid electrolyte for galvanic lithium cells, Li.sub.3 N powder is first stirred together with molten Li-metal serving as binder, in a noble gas atmosphere. After cooling, the mixture is pressed into a shaped body and the shaped body is then sintered in nitrogen at temperatures of about 700.degree. C. This causes the Li-binder to also become transformed into Li.sub.3 N. The binding with lithium also makes the powdery starting material suitable for rolling, and shaped bodies such as tablets can be cut out of the ductile rolled product with high precision.

Abstract: A method for hot-consolidating powder of metallic and nonmetallic composition and combinations thereof to form a densified compact at a predetermined temperature and pressure at which the powder is transformed into a compact comprises the steps of filling the cavity of a container with a powder, such as a superalloy, to be compacted and hermetically sealing the container. The method is characterized by the steps of heating the container within an autoclave having an inert gas therein, such as argon, to an intermediate temperature, then pressurizing the autoclave to an intermediate temperature and thereafter raising the temperature to thereby increase the pressure and, consequently, reach the temperature and pressure to effect compaction or densification of the compact or article.

Abstract: A process for producing a translucent .beta.-sialon sintered product, which comprises mixing fine powders of silicon nitride and aluminum nitride having a high purity of at least 99% and a particle size of at most 200 microns and fine powders of aluminum oxide and silicon oxide having a high purity of at least 99% in such a proportion as to form .beta.-sialon of the formula Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z where z is from 1 to 4.2, and hot-pressing the mixture in a nitrogen atmosphere at a temperature of from 1500.degree. to 1850.degree. C. under pressure of from 10 to 1500 kg/cm.sup.2.

Abstract: A material for magnetic head sliders comprises a mixed powder consisting of 40 to 80% by weight of Al.sub.2 O.sub.3 and 20 to 60% by weight of TiO.sub.2, and further contains, per 100 parts by weight of the Al.sub.2 O.sub.3 and TiO.sub.2 mixture, 0.5 to 5 parts by weight of at least one of CaO, MgO and Y.sub.2 O.sub.3, and 0.5 to 10 parts by weight of ZrO.sub.2.

Abstract: Optically translucent theoretically dense body of mullite is produced by pressing an amorphous mixed oxide powder composition of from about 72.5 weight % to about 76.5 weight % Al.sub.2 O.sub.3 /balance SiO.sub.2 into a compact of density of at least 1.0 g/cc, sintering the compact in oxygen or a vacuum of 0.05 torr to 1 torr producing a gas-impermeable compact, hot isostatically pressing the gas-impermeable compact to theoretical density, and with respect to compositions ranging from higher than about 74 wt % Al.sub.2 O.sub.3 /balance SiO.sub.2, annealing the theoretically dense body.

Abstract: This invention concerns thermoplastic polyester molding compositions containing iron oxides, particularly Fe.sub.2 O.sub.3 which compositions exhibit markedly reduced heat up times and are especially useful in molding operations such as blow molding of beverage bottles. The polyester polymer may have incorporated therein by copolymerization certain anthraquinone dyes having functional groups which condense during polymerization into the polyester chain. The dye moieties are thermally stable at the polymer processing temperatures and are colorfast and non-extractable from the polymer.

Abstract: A method of preparing a ceramic body of high toughness from an aluminum oxide matrix forming ceramic material by using a ceramic embedment material to generate tensile stresses for the formation of controlled microfissures, is provided. The ceramic embedment material comprises 4 to 25% of the volume of the body to be formed, of unstabilized zirconium dioxide and/or hafnium dioxide with a particle size of 0.3 to 1.25 um. This is mixed with the aluminum oxide material and the mixture is sintered by hot-pressing in a mold at a temperature of 1400.degree. C. to 1500.degree. C.

Abstract: Amorphous mixed oxide powder composed of from about 74 weight % to about 76.5 weight % Al.sub.2 O.sub.3 balance SiO.sub.2 is pressed into a compact with a density of at least 1 g/cc, fired in oxygen or vacuum of 0.05 to 1 torr producing a gas-impermeable compact, and sintered in air, argon, helium, nitrogen or mixtures thereof producing an optically translucent theoretically dense body of mullite.

Abstract: Oxide refractory materials (for example, alumina-zirconia mixtures) can be cast to have an extremely fine crystal structure by casting them onto a non-reactive, non-melting particulate solid cooling media of a material other than that of the oxide refractory material (for example, steel spheres having a size ranging from about 5 to about 60 mm). By using steel spheres as the cooling media, the spheres can be removed from the solidified material with a magnet. The solidified material, when crushed and graded, has exceptional utility as an extremely tough abrasive grain.

Abstract: A method is provided for converting polycrystalline ribbon to macrocrystalline ribbon in which a molten zone is formed in and moved along the polycrystalline ribbon. Macrocrystalline material in ribbon shape is formed as the molten region passes and the molten material resolidifies. The molten zone is formed in the polycrystalline ribbon by impinging energy beams from two energy sources on the two major surfaces of the ribbon. The combined energy from the first and second energy sources is sufficient to melt the ribbon material and to form a molten zone extending through the thickness of the ribbon. The molten zone has an intersection with each of the major surfaces of the ribbon. The two energy sources are adjusted independently to control the area of the intersection of the molten zone with each surface so that the areas are non-identical.

Abstract: An improved heat exchanger for high energy laser mirrors is provided which comprises one or more sections each hot pressed into a desired configuration to define coolant passageways, and subsequently stacked and joined by a suitable means such as diffusion bonding. A surface of one of the sections may either support a laser mirror faceplate or be finished to provide the desired laser mirror surface.

Abstract: A method and apparatus is disclosed for rapidly solidifying and cooling molten metal oxides, by continuous casting, which according to the invention, comprises: feeding the molten metal oxides into the convergent space formed between two cylinders mounted for rotation about horizontal axes and rotated in opposite directions, i.e., counter-rotating, at a substantially equal peripheral speed, the distance between their axes being equal to the sum of the radius of each cylinder plus at least about one millimeter; cooling the walls of the cylinders to enable solidification of the molten material; controlling the rotary speed of the cylinders so that the molten metal oxide is not completely solidified until it reaches a point beyond a plane passing through the axes of rotation of the cylinders, and retrieving a solidified metal oxide product from the divergent space formed between the cylinders. The method is particularly suited to the production of fine grain abrasives of a corundum or courndum-zirconia base.

Abstract: A method is disclosed comprising placing in a hot pressing environment a controlled mixture of a first powder of Si.sub.3 N.sub.4 containing a controlled amount of SiO.sub.2 (with or without a limited amount of milling media) with a second powder consisting essentially of Y.sub.2 O.sub.3, hot pressing the controlled mixture, and cooling the resultant unitary object.A novel silicon nitride comprising a unitary object is disclosed which can be shaped to form a novel cutting tool useful for machining metal such as cast iron. The object has selected crystalline phases formed beta Si.sub.3 N.sub.4 and beta prime Si.sub.3 N.sub.4 and as intergranular crystalline secondary phases consisting essentially of YSiO.sub.2 N, y.sub.10 Si.sub.17 N.sub.4 O.sub.23 and Y.sub.2 Si.sub.2 O.sub.7 with the YSiO.sub.2 N phase representing at least a 25% volume fraction of the secondary phases and comprising essentially all of the yittria-silicon oxide.

Abstract: Method for producing .alpha.-silicon nitride whiskers. Silicon is blended with composition particles able to sublime without leaving a residue, such as naphthalene particles. The blend is compacted to a desired shape, after which the composition particles are sublimed from the blend to form a porous silicon precursor compact having the desired shape. The silicon precursor is reacted with a substance that releases free nitrogen, such as nitrogen or dry ammonia. The reaction is carried out at a temperature sufficiently high to form an identically shaped porous compact of .alpha.-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of the formed whiskers. Preferably, the reaction is carried out in a range between about 2100.degree. F. and 2750.degree. F. The shaped porous compact of .alpha.-silicon nitride whiskers may be impregnated with a resin binder, a liquid metal, a colloidal suspension, an ionic solution or a gaseous material to form an isotropic composite.

Abstract: A thermally stable, oxidation resistant ceramic Si.sub.3 N.sub.4 material is disclosed. The material has a substantially pure primary phase formed of substantially pure silicon nitride. A substantially pure secondary phase of the material is formed of a material selected from the group consisting essentially of Si.sub.3 N.sub.4 /SiO.sub.2 /4Y.sub.2 O.sub.3, Si.sub.3 N.sub.4 /SiO.sub.2 /2Y.sub.2 O.sub.3 and Si.sub.3 N.sub.4 /4SiO.sub.2 /5Y.sub.2 O.sub.3. The primary phase may be in the form of individual grains and the secondary phase may be in the form of grain boundaries between the individual grains.

Abstract: Compositions are disclosed for securing Si.sub.3 N.sub.4 parts together, these compositions being in the .beta.'-Y.sub.2 Si.sub.2 O.sub.7 --Y.sub.3 Al.sub.5 O.sub.12 tetrahedron, e.g. compositions in mole % comprising (1) 15% Si.sub.3 N.sub.4, 79.1% Y.sub.2 Si.sub.2 O.sub.7 and 6.9% Y.sub.3 Al.sub.5 O.sub.12 or (2) 25% Si.sub.2 AlON.sub.3 and 75% Y.sub.3 Al.sub.5 O.sub.12 Y. A method of securing Si.sub.3 N.sub.4 parts together comprises placing the composition between the parts to be bonded and heating to brazing temperature (about 1600.degree. C.) in nitrogen.

Abstract: Dense, composite, polycrystalline ceramic articles comprising silicon nitride, silicon dioxide, and yttrium oxide and having thin surface layers of controlled composition are formed by sintering pre-pressed compacts embedded in setter bed powder mixtures having compositions of silicon nitride, silicon dioxide, and yttrium oxide which differ from that of the pressed compact.Employing the method of this invention, articles are produced which have surface layers in which the minor phase of the article is enriched with either yttrium or silicon.

Abstract: A process for annealing a heat fused cast refractory product casts a molten refractory material in a mold which is held in a heat insulating material as an annealing medium, said mold being held in said packed heat insulating material which has a thermal conductivity ranging from 0.04 to 0.3 Kcal/m. hr. .degree.C. (at 200.degree. C.) as a heat insulating property and a contraction coefficient of up to 45% under a pressure of 50 Kg/cm.sup.2 as a mechanical strength for supporting a mold.

Abstract: A high frequency ultrasonic transducer is improved by fabricating the tungsten-polyvinyl chloride composite, which backs the elements, in a specific manner. Small particle size tungsten powder and PVC powder are placed into a high pressure die. Standard processing of the powder mixture includes degasing followed by heating and compressing. To maximize the acoustic attenuation, the pressure applied to the mixture is maintained until it has cooled down. The composite is in a state of elastic compression and spontaneously expands when removed from the die, giving rise to the high levels of acoustic attenuation.

Abstract: A method is disclosed in this specification for forming a densified silicon nitride article. The method is initiated by forming a reaction bonded article of moderate density. This moderate density reaction bonded article has a primary phase of substantially pure grains of silicon nitride surrounded by a secondary grain boundary phase. The secondary grain boundary phase contains silicon nitride, silicon dioxide and a densification aid incorporated in the reaction bonded article of moderate density. The compounds forming the secondary grain boundary phase are present either in their pure forms or interacted with one another. The reaction bonded article is packed in a packing powder which contains portions of the pure compounds found in or interacted with one another to define the secondary grain boundary phase.

Abstract: The invention relates to a fused cast block useful in the construction of steel making furnaces, the block comprising a refractory oxide-based material having embedded therein a steel member which extends over the greater part of the length of the block and emerges from the block on the outer face of the latter, the steel member being embedded in the block in the course of molding the latter and having a cross-section of suitable shape and surface area to impart to the composite block an apparent thermal conductivity at between 500.degree. and 1000.degree. C. of at least 8 Kcal. m./m.sup.2..degree.C. hr.

Abstract: A compact composed of a mixture of silicon nitride with less than about 0.5 weight % cation impurities and containing beryllium additive, and having an oxygen content of at least about 1.4 weight %, is sintered from 1900.degree. C. to 2200.degree. C. in nitrogen at superatmospheric pressure producing a sintered compact of at least about 80% density.

Abstract: A method of producing a dense sintered silicon carbide body, which is high in flexural strength, purity and strength at an elevated temperature, from polycarbosilanes is disclosed. This method comprises the following steps of:A. polymerizing organosilicon compounds to obtain insoluble and unmeltable polycarbosilane of which the melting or softening temperature lies higher than its thermal decomposition temperature;B. grinding this insoluble and unmeltable polycarbosilane to powder;C. decomposing this powder thermally in the range of 600.degree. to 2200.degree. C. in a nonoxidizing atmosphere to obtain silicon carbide;D. molding this silicon carbide powder; andE. sintering the thus molded body in a nonoxidizing atmosphere.

Abstract: A method for casting parts of fused ceramic material, from a bath of oxides maintained in the liquid state in a furnace and permanently covered by a layer of powdery batch material are disclosed. The method comprises the following steps:(a) connecting the mold internal cavity, through its lower part, to a downwardly directed feed duct,(b) dipping the lower end of said duct in the liquid bath,(c) establishing in the mold a vacuum causing the bath liquid to rise in the duct and in the mold,(d) allowing the product to solidify in the duct;(e) lifting the mold, together with the duct, and transporting the same apart from the furnace,(f) allowing complete solidification of the product in the mold.Preferably material is removed on a limited area of the bath surface by being swept away with a downwardly directed gas jet, for instance flowing through the feed duct is then lowered through this area free of powdery material into said liquid bath.

Abstract: This invention comprises a method of ultrasonically end-capping a tubular green body which comprises a mixture of 40-60 volume percent sinterable beta"-alumina precursor particulate and 60-40 volume percent organic sacrificial binder wherein said sacrificial binder comprises a thermoplastic elastomer, a plasticizer which may be oil, wax or oil and wax, stiffening polymers, a processing aid and optional components. The tube is preferably formed by extrusion molding. The green body tube may be end-capped by ultrasonic forming or by ultrasonic bonding of an end-cap to the tube. During this process, ultrasonic vibration energy is dissipated as heat energy which melts the thermoplastic binder composition and welds the joining surfaces.

Abstract: A method for manufacturing a thin and flexible ribbon wafer of semiconductor material such as germanium, silicon, selenium, tellurium, PbS, InSb, ZnTe, PbSe, InAs, InP, GaSb, PbTe, ZnS, Bi.sub.2 Te.sub.3, and mixtures thereof comprises melting the semiconductor material at a temperature within the range from a melting point thereof to 300.degree. C. above the melting point to form a uniform melt; ejecting under a pressure the melt through a nozzle against a cooling surface of a moving substrate to cool very rapidly a jet flow of the melt at a cooling rate of 1,000.degree. C. to 1,000,000.degree. C./sec to form the ribbon type thin and flexible wafer of fine and compact microscopic structure having a large mechanical strength and an excellent electrical property. It is possible to add to the melt various additives as fluxes or impurities such as B, P, BP, Sb Sn, As, B, P, Sb, In, Al and alloys intermetallic compounds, and conjugates thereof.

Abstract: Thermally collapsible core of three to five solid carbonaceous segments of generally equal volume and of wedge-like shape arranged around a collapse axis of the core in narrowly spaced apart relation to each other. Core includes spacers occupying a minor portion of the narrow spacing nearest the external periphery of the core and which are made of metal, glass, ceramic or mixtures thereof having a melting point below the highest temperature to which the core is subjected by molten material solidifying therearound, e.g. fusion-cast refractory. The segments are the larger parts of the core. Heat transferred from solidified molten material to core causes spacers to melt and allow segments to collapse inwardly toward collapse axis to accommodate cooling shrinkage of casting without cracking. Melted spacers can drain downwardly out of core. Design yields highly quenched microstructure in fusion-cast refractory, which is especially beneficial in tap hole blocks for steelmaking furnaces and vessels.

Abstract: An apparatus and process is provided for electromagnetically casting molten material into a desired shape. A containment zone is established. The containment zone has a first section for electromagnetically containing the molten material and a second section downstream and communicating with the first section for forming the molten material into the desired shape. The improvement comprises a heat extraction device for directing a cooling medium into the containment zone whereby the cooling medium passes the molten material in the second section to rapidly solidify the molten material prior to passing the molten material in the first section to lower the temperature in the contained molten material to minimize superheating. A second embodiment of the invention includes a secondary cooling device associated with the heat extraction device for directing a cooling medium against the solidified material.

Abstract: A laser mirror stable at high and low temperatures is described comprising graphite fibers in a glass matrix. The mirror is made by hot pressing a graphite fiber lay-up in a glass matrix in a die having a highly polished mirror replicating surface, the fibers laid up in such a way to produce a central plane of symmetry across the central plane of the composite. In use, the composite requires a separate laser reflecting surface layer. The resulting laser mirror has a low density but no porosity, high elastic stiffness, high strength, high fracture toughness, low thermal expansion, high thermal conductivity and environmental stability.

Abstract: Method for preparing finely divided high purity alumina doped with a small predetermined percentage of magnesia. In the preparation, there is first formed a mixed clear solution of aluminum alkoxide and a small amount of magnesium in the form of alkoxide or water soluble magnesium salt. There is then included with the clear solution a substantial excess of water over that required to completely hydrolyze the alkoxide and there is added thereto a small amount of selected acid which is effective to peptize the resulting slurry. The formed milky slurry is then allowed to become fully peptized to form a clear sol. The clear sol is converted to a finely divided and dried powder either by forming the sol into a gel, which is then dried, and mechanically reduced to a powder status or by spray drying the sol at elevated temperatures which produces the dried powder. Thereafter, the finely divided and dried powder is calcined at a temperature of from about 700.degree. C. to about 900.degree. C.

Abstract: Process for the production of a ceramic member having inclusions of electrically conductive material flush with its surface, wherein it comprises depositing on the bottom of a mould a small number of particles of said conductive material, placing above said particles the ceramic powder and compressing together the aggregate formed by the powder and the particles, followed by fritting at a temperature below the melting temperature of the conductive material.Cathode--solid electrolyte assembly obtained by using the above process.

Abstract: Silicon (Si) is cast into thin shapes within a flat-bottomed graphite crucible by providing a melt of molten Si along with a relatively small amount of a molten salt, preferably NaF. The Si in the resulting melt forms a spherical pool which sinks into and is wetted by the molten salt. Under these conditions the Si will not react with any graphite to form SiC. The melt in the crucible is pressed to the desired thinness with a graphite tool at which point the tool is held until the mass in the crucible has been cooled to temperatures below the Si melting point, at which point the Si shape can be removed.

Abstract: Submicron titanium diboride powder and other hard, refractory metal boride powders, such as zirconium diboride and hafnium diboride powders, are prepared by vapor phase reaction of the corresponding metal halide, e.g., titanium halide, and boron source reactants in the presence of hydrogen in a reaction zone and in the substantial absence of oxygen, either combined or elemental. In a preferred embodiment, the metal halide, e.g., titanium tetrachloride, and boron source, e.g., boron trichloride, reactants are mixed with a hot stream of hydrogen produced by heating hydrogen in a plasma heater. The reaction zone is maintained at metal boride forming temperatures and submicron solid metal boride powder is removed promptly from the reactor and permitted to cool. The preponderant number of metal boride particles comprising the powder product have a particle size in the range of between 0.05 and 0.7 microns.

Abstract: A process for simultaneously cementing diamond fines together and bonding the cemented diamonds to a silicon-silicon carbide composite is described. During the process the silicon-silicon-carbide composite furnishes silicon for the cementing and bonding function and the silicon-silicon carbide composite provides for the structural stability of the resulting article. The process comprises placing a quantity of diamond powder and a mass of silicon-silicon carbide composite adjacent to each other, packing such material to form a stabilized geometry, heating the stabilized geometry in an inert atmosphere, and simultaneously applying pressure thereto.

Abstract: A temperature sensitive element comprises fine grain powders which consist of a spin reorientation type ferromagnetic material having a transition temperature range, below which transition temperature range the easy direction of magnetization of the spin reorientation type ferromagnetic material is predetermined in one crystallographic direction thereof and above which transition temperature range the easy direction of magnetization is a predetermined other direction perpendicular to the predetermined one crystallographic direction. The temperature sensitive element is produced by compacting the fine grain powders of a spin reorientation type ferromagnetic material at a temperature higher than the transition temperature range. A polycrystalline rare earth cobalt alloy material made in accordance with the invention can now be used in the field where low Curie point ferrite or where bimetals have been used previously for a thermal valve or a temperature controlling device.