Abstract: The present invention relates to high performance ceramics and methods for their production using supercritical temperatures and supercritical pressures. Furthermore, the present invention relates to high performance ceramics for use in the automobile industry.

Abstract: For producing crystalline sodium silicates having a layer structure, an SiO.sub.2 /Na.sub.2 O molar ratio of (1.9 to 2.1):1 and a water content of less than 0.3% by weight from a waterglass solution containing at least 20% by weight of solids, the waterglass solution is obtained by reacting quartz sand with sodium hydroxide solution at an SiO.sub.2 /Na.sub.2 O molar ratio of (2.0 to 2.3):1 at temperatures of 180.degree. to 240.degree. C. and pressures of 10 to 30 bar. This waterglass solution is treated in a spray-drying zone with hot air at 200.degree. to 300.degree. C. for a residence time of 10 to 25 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90.degree. to 130.degree. C., to form a pulverulent amorphous sodium silicate having a water content (determined as the loss on ignition at 700.degree. C.) of 15 to 23% by weight and a bulk density of more than 300 g/l.

Abstract: The invention is a process for preparing amorphous silica alumina spherical particles by mixing sodium silicate or silicic acid gel with sodium aluminate and sodium hydroxide in an aqueous solution to form a gel, homogenizing the formed gel, crystallizing this intermediate product at 85.degree. C. to 200.degree. under atmospheric pressure or under hydrothermal conditions to form spherical zeolite particles with an x-ray diffraction pattern inherent to P-type zeolites and with a notched surface, treating the zeolite particles with acid to remove the sodium, thereby rendering the particles amorphous.

Abstract: Precipitated silica gels having high surface areas and low oil absorption values are produced by a low temperature synthesis precipitation process. The precipitated silicas have unique flatting characteristics and are additionally useful as conditioning agents for food and salt and in dentifrice formulations.

Abstract: An organosilicon high molecular compound having a skeleton of silicon and carbon or a compound obtained by polymerization of an organometallic compound and the organosilicon high molecular compound is melted into a fiber, then the fiber is antimelt-treated in an oxidizing atmosphere, and the antimelt-treated yarns are thereafter heated in an atmosphere of inert gas to obtain a fiber of silicon carbide containing 2 to 20% by volume of oxygen. This fiber is further sintered in an atmosphere of inert gas at a temperature of 1400 to 2100 deg. C. and a pressure of 300 to 3000 kg/cm.sup.2. A sintered body of silicon carbide having an excellent bending strength is obtained without the use of a sintering agent or a binder. A fiber of silicon carbide having a predetermined oxygen content and a thin amorphous carbon layer thereon is obtained from the starting fiber by antimelt-treating and then heating in an atmosphere of a mixture of an inert gas and a hydrocarbon gas.

Abstract: Silicon nitride powder is produced in two steps, by supplying metallic silicon powder to a fluidized bed composed of silicon nitride and nitrogen or ammonia gas where primary nitriding reaction is effected until the silicon powder is nitrided to an amount of at least 50% and transferring the nitrided product from the fluidized bed into a moving bed where secondary nitriding reaction is effected for nitriding the unreacted silicon with nitrogen or ammonia gas. This method is adapted for manufacture on a commercial scale because the silicon nitride powder thus obtained is consistent and has a very high degree of nitriding and a minimal variation in quality.

Abstract: A method of improving surface morphology of a laser irradiated surface includes a first step of irradiating a pulse laser beam one or a plurality of times on a region of a conductor layer which is formed on an under layer so as to melt the entire conductor layer, and a second step of irradiating a pulse laser beam on the irradiated region of the conductor layer at least once after the first step with an energy density such that only a surface portion of the conductor layer melts in substantially the entire irradiated region.

Abstract: A method of producing a semiconductor-on-insulator structure generates a first fixed charge in an insulator layer of a base substrate. An active substrate which is made of a semiconductor is bonded on the insulator layer of the base substrate to thereby generate a second fixed charge at an interface of the insulator layer and the active substrate. The first and second fixed charges have mutually opposite polarities. A portion of the active substrate is removed to form the active substrate to an arbitrary thickness.

Abstract: There is provided a method for the production of a silicon carbide single crystal, which includes the steps of: providing a silicon single-crystal substrate having a growth plane with a crystal orientation inclined from the [100] direction toward an off-direction, wherein the crystal orientation is defined by a deviation angle .theta. of 5 to 40 degrees, as measured from the [011] direction toward the [011] direction, and a tilt angle .phi. of 1 to 7 degrees, as measured from the [100] direction toward the off-direction; and growing a silicon carbide single crystal on the substrate.

Abstract: A suitable inert gas such as argon or a mixture of inert and reactive gases such as argon and hydrogen is introduced onto the backside of wafers being processed in a CVD reactor during the deposition of tungsten or other metals, metal nitrides and silicides, to avoid deposition of material on the backside of the wafers being processed. Each process station includes a gas dispersion head disposed over a platen. A vacuum chuck including a number of radial and circular vacuum grooves in the top surface of the platen is provided for holding the wafer in place. A platen heater is provided under the platen. Backside gas is heated in and about the bottom of the platen, and introduced through a circular groove in the peripheral region outside of the outermost vacuum groove of the vacuum chuck. Backside gas pressure is maintained in this peripheral region at a level greater than the CVD chamber pressure.

Abstract: A process for producing amorphous sodium silicates having a water content of 0.3 to 6% by weight and an SiO.sub.2 /Na.sub.2 O molar ratio of (1.9 to 2.8) : 1 from a waterglass solution containing at least 20% by weight of solids, the water-glass solution is obtained by reacting quartz sand with sodium hydroxide solution at an SiO.sub.2 /Na.sub.2 O molar ratio of (2.0 to 2.8) : 1 at temperatures of 180 to 240.degree. C. and pressures of 10 to 30 bar. This waterglass solution is treated in a spray-drying zone with hot air at 200 to 300.degree. C. for a residence time of 10 to 20 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90.degree. to 130.degree. C., to form a pulverulent amorphous sodium silicate having a water content (determined as the loss on ignition at 700.degree. C.) of 15 to 23% by weight and a bulk density of more than 300 g/l.

Abstract: A method for making mullite whiskers includes the steps of:preparing a mullite-intensive sol by mixing an alumina sol with a silica sol at a molar Al.sub.2 O.sub.3 /SiO.sub.2 ratio of 1.37-1.76,gelating said mullite-intensive sol by adding HF thereto at a molar HF/3Al.sub.2 O.sub.3 .multidot.2SiO.sub.2 ratio of 0.01-0.1,drying the gel at a temperature lower than 120.degree. C.; andcalcining the dried product in an open system at a temperature up to 1000.degree. C. and in a closed system at a temperature from 1200.degree.-1600.degree. C.

Abstract: The subject invention is a new type of silica gel and process for producing the same. The silica gel is the product of gelling alkali metal silicate with excess acid in aqueous medium containing a minute amount a polymerization modifier. The modifier and salts from the resulting gel are then leached with water before substantial drying effects have ensued. Spray-dried gel particles do not require the additional steps of aging or ammonia treating to achieve the desired result of high surface area and high pore volume. The gel can be produced to have various useful and unusual characteristics including the combination of high surface area, high pore volume, and a large average pore diameter.

Abstract: The invention relates to talc substances consisting of particles having a sheet structure. These substances are characterised in that each particle has internally the crystalline structure of talc which confers upon it certain specific properties of this mineral (softness, thermal stability) and has hydrophilic surface properties unlike the hydrophobic properties of mineral talc which give rise to useful reactivity. The substances according to the invention have a thermal and chemical stability range similar to that of talc. They can be manufactured by thermal or chemical means under conditions designed to avoid internal conversion of the talc and to effect the surface modifications consisting of replacing inert siloxane bridges by active hydrophilic groups.

Abstract: This invention relates to a process for the production of a usable or storable product with a low susceptibility to elutriation by water. This product is produced from residues containing halides obtained from a waste gas cleaning process. The halide containing residues as components of a crude dust having a CaO/SiO.sub.2 ratio between 1.7 and 3.4, are subjected to a thermal treatment to produce chlorosilicates. The waste gases formed during the thermal treatment for chlorosilicate production are subjected to a preliminary cleaning, and are then transported to the waste gas cleaning system of a refuse incineration plant. The residues occurring during the preliminary cleaning can be added to the crude dust.

Abstract: A process for making local interconnection of devices on a semiconductor substrate is disclosed. Contact openings are defined to a plurality of devices on the substrate. A blanket layer of germanium is deposited over the substrate, followed by deposition of a blanket layer of electrically conducting material on top of the germanium layer. The conducting layer is etched first stopping at the germanium layer. Subsequently the germanium layer is etched by a different process, selective to the conductive layer and the device contact. The conducting layer is preferably one of the following materials: polysilicon, silicide, a composite of polysilicon with metal or silicide films.

Abstract: The present invention provides a process for the vapor-phase epitaxial growth of a Si single crystal film on a Si single crystal substrate using diluted disilane, in which the process is carried out at a linear speed of diluted disilane on the surface of the Si single crystal substrate is in the range of 5 to 100 cm/min. and, as desired, the substrate is subjected to the heat pretreatment in a hydrogen stream at a temperature of 1,000.degree. C. or higher for a period of 30 minutes or longer before the epitaxial growth.

Abstract: A process for producing silicon carbide whiskers in which a particulate form of carbon is combined with a silicon component, a boron component and seeding component to form a mixture which is then subjected to temperatures above about 1300.degree. C. in a nonoxidizing atmosphere such that carbon reacts with silica to form silicon carbide whiskers. The preferred particulate carbon, silicon component, boron component and seeding component are, respectively, carbon black, fumed silica, boron oxide and cobalt, iron or nickel. The size and shape of the whiskers can be controlled by varying the size of the seeding component and the concentration of the boron component.

Abstract: Method for producing alkali metal silicates from crystalline siliceous material and aqueous alkali metal hydroxide solution at high temperature and normal pressure, characterized in that cristobalite and/or tempered quartz sand are used as the siliceous material, and this material is reacted with aqueous, 20 to 50 wt. % sodium or potassium hydroxide solution at temperatures of 100.degree. to 150.degree. C. and normal pressure, the molar ratio of SiO.sub.2 to Na.sub.2 O or K.sub.2 O in the reaction mixture being between 2:1 and 1:7.

Abstract: Amorphous silica prepared by the gel route requires washing to remove electrolyte. The gel is formed into small particles by shearing and then washed while being transported by water through stages which separate larger size material. The washing is more rapid than conventional methods and allows the ageing steps to be decoupled from the wash stage.