Abstract: The manufacture of semiconductor devices and, specifically, deposition of SiO.sub.2 films on semiconductor devices by oxidative decomposition of oligo siloxanes at low temperature is disclosed.

Abstract: Coatings, which act as barrier layers to inhibit migration of alkali metal ions from a glass surface and/or act as color suppressing underlayers for overlying infra-red reflecting or electrically conducting layers, are deposited by pyrolysis of a gaseous mixture of a silane, an unsaturated hydrocarbon and an oxygen-containing gas other than carbon dioxide which does not react with the silane at room temperature on a hot glass surface at a temperature of 600.degree. C. to 750.degree. C.

Abstract: A spherical, hydrophilic silica consisting of compact, massive, non-crystalline particles without inner pores with a particle size of 0.5 to 10 .mu.m, preferably 0.5 to 4 .mu.m and especially 1 to 3 .mu.m with a BET surface of <50 m.sup.2 /g, preferably of 1 to 10 m.sup.2 /g is prepared by heating water vapor and gaseous silicon tetrachloride separately to a temperature of 300.degree. to 400.degree. C., mixing them with each other in a molar ratio of 2:1 to 6.7:1 and reacting the mixture at a temperature of 600.degree. to 1200.degree. C.

Abstract: The present invention relates to a process for treating combustible exhaust gases containing poisonous and combustible component gases such as silane and so on, and a combustion system therefor. In the combustion system, the combustible exhaust gases are burnt by downward flames generated from a coaxial, fourfold-pipe burner wherein the flow rates of primary and secondary air are regulated, thereby preventing fine particles of oxides such as silicon dioxide resulting from the combustion of silane, etc. from being deposited onto the nozzle of said burner and allowing deposites, if any, to peel off immediately. Thus, there is no fluctuation in the pressure of the a combustible exhaust gas path, so that constantly stable and continuous combustion is achieved with no difficulty. Removal of dust contained in the exhaust gases comprising fine particles of silicon dioxide, etc.

Abstract: A method and apparatus for producing a directed aerosol stream from gaseous and/or vapor phase reactants by conveying the reactants to a reaction site, reacting the reactants at the reaction site in a flame free chemical reaction to produce an aerosol composition, and causing the aerosol composition to flow from the reaction site and immediately surrounding the aerosol composition with a moving, essentially aerosol free gas and/or vapor stream to form a directed aerosol stream enveloped in the aerosol free stream, in which the step of conveying includes conducting each reactant through a respective distributor and then through a discharge element having a substantially higher flow resistance than the distributor in a substantially vertical upward direction to the reaction site, and the step of causing is carried out so that the aerosol composition flows in a substantially vertical upward direction.

Abstract: An improved supercritical drying process for forming transparent silica aerogel arrays is described. The process is of the type utilizing the steps of hydrolyzing and condensing aloxides to form alcogels. A subsequent step removes the alcohol to form aerogels. The improvement includes the additional step, after alcogels are formed, of substituting a solvent, such as CO.sub.2, for the alcohol in the alcogels, the solvent having a critical temperature less than the critical temperature of the alcohol. The resulting gels are dried at a supercritical temperature for the selected solvent, such as CO.sub.2, to thereby provide a transparent aerogel array within a substantially reduced (days-to-hours) time period. The supercritical drying occurs at about 40.degree. C. instead of at about 270.degree. C. The improved process provides increased yields of large scale, structurally sound arrays.

Abstract: Process and apparatus are provided for preparing finely-divided silicon dioxide in good yield by reaction of silicon fluoride in the vapor phase with water vapor, combustible gas and free oxygen-containing gas in a flame reaction zone to form hydrogen fluoride and silicon dioxide entrained in a gaseous reaction mixture; withdrawing the gaseous reaction mixture from the flame reaction zone; and then immediately and rapidly cooling the gaseous reaction mixture and entrained silicon dioxide to a temperature below 700.degree. C. by passing the gaseous reaction mixture in a turbulent flow at a Reynolds number above 300 under constraint through a straight narrow passage in alignment with the gas flow, the passage having a diameter within the range from about 20 to about 150 mm and smooth walls constituting a cooling surface.

Abstract: A process for the production of pyrogenic silicic acid having an increased thickening effect which comprises subjecting silicon-containing materials to a pyrolysis flame while introducing additional energy into the flame. The invention also relates to the product so obtained, particularly useful for articles of dental care.

Abstract: Process and apparatus are provided for preparing finely-divided silicon dioxide having high thickening capacity and good thixotropic properties by reaction of silicon fluoride in the vapor phase with water vapor, combustible gas and free oxygen-containing gas in a flame reaction zone to form silicon dioxide and hydrogen fluoride while cooling the gaseous reaction mixture in that portion of the reaction zone adjacent the base of the flame by contact with a cooling surface maintained at a temperature below 500.degree. C. but above the dew point of the reaction waste gases generated in the flame reaction.

Abstract: A method of burning exhaust gases containing gaseous silane in which the exhaust gases containing gaseous silane to be introduced into a combustion chamber are diluted with an inert gas so that the concentration of silane gas is reduced to less than 30% by volume and the diluted exhaust gases are fed from a nozzle to the combustion chamber and burnt through reaction with air in the combustion chamber while the region between the head of the nozzle top end and the base portion of the burning flame is shielded with an inert gas atmosphere.An inert gas mixing pipe is connected for dilution to an exhaust gas feed section, an enclosure pipe is fitted to the outer circumference of an exhaust gas introduction pipe introduced into the combustion chamber to constitute a double pipe structure, and the enclosure pipe is connected at the rear end thereof to an inert gas feed pipe and slightly protuded at the top end thereof ahead of the top end for the exhaust gas introduction pipe.

Abstract: A method for treating fumed silica in a continuous manner is provided by effecting contact between the fumed silica, while in a fluidized state, with a methyl substituted chlorosilane, hydrochloric acid and a surfactant.

Abstract: A method for separating and recovering substantially pure aluminum, iron and silica from fly ash, a by-product of coal combustion, includes reacting the fly ash with aqueous fluosilicic acid and aqueous hydrogen fluoride at temperatures sufficiently high to form aqueous silicon fluoride vapor and fluorides and fluosilicate of aluminum and iron, separating the aluminum and iron fluorides and fluorosilicates from the aqueous silicon fluoride vapor, hydrolizing the silicon fluoride vapor to form silicon dioxide in substantially pure form and hydrogen fluoride, recovering and recycling the hydrogen fluoride for reuse in the process, and separating the aluminum and iron fluorides and fluosilicates from one another, and recovering substantially pure aluminum fluoride, substantially pure iron and other substantially pure metals, by electroplating or otherwise.

Abstract: A method of recovering fumed hydrophobic SiO.sub.2, produced by the flame hydrolysis of a ternary azeotrope of H.sub.2 SiF.sub.6, HF, and H.sub.2 O, is disclosed. The method involves passing the fumed hydrophobic silica, as it leaves the combustion chamber, through a nonclassifying agglomerator at a residence (travel) time of from about 0.5 to several seconds, preferably about 1.0 to about 5.0 seconds, then separating the fumed silica from the product stream in a cyclone separator or other means for collecting dispersoids.

Abstract: Pyrogenically produced silica after separation of the hydrogen halide is mixed with nitrogen and conveyed into a cyclone. After separation of the gases, which are returned into the cooling stretch of the production apparatus, the silica is first mixed with organohalosilane and nitrogen and subsequently with steam and nitrogen. Subsequently the hydrophobization reaction is carried out in known manner in a fluidized bed reactor. The reaction waste gases are returned into the cyclone.

Abstract: A method for separating chlorosilanes from a gaseous mixture which additionally contains hydrogen and hydrogen chloride by washing the gaseous mixture with saturated hydrochloric acid is disclosed. The resulting chlorosilane hydrolysis products can remain in the hydrochloric acid serving as washing liquid, without interfering with the purifying action. The suspended hydrolysis products are easily filtrable, and can be periodically separated from the hydrochloric acid. In a preferred embodiment, the hydrochloric acid is recirculated and injected into the gas stream being washed.

Abstract: A method for reducing surface-area decay of fluoride-containing fumed silica which comprises the step of providing an atmosphere of inert gas in which the fumed silica is disposed. The method, which can be used at ambient temperature, is particularly effective for the storage of a fluoride-containing fumed silica product prepared by a fluoride process, which fumed silica contains between about 2 and about 4 percent fluoride by weight.

Abstract: In the method for manufacturing a non-sintered quartz ware the quartz and clay are comminuted and fully mixed to make a batch of raw materials. The batch is then added with an effective amount of ore coagulant of which the composition comprises 2CaO.SiO.sub.2, 3CaO.SiO.sub.2 and 3CaO.Al.sub.2 O.sub.3, subsequently, the above components are blended with water and then molded into the desired shape by extrusion pressing. The molded product is then dried under slightly higher than the ambient temperature instead of firing which results in less mechanical strength of the conventional fired ceramic ware.

Abstract: A thermal insulating flexible ceramic based on a microporous oxide aerogel obtained from flame hydrolysis, especially a silica aerogel with elastically bending or limply bending inorganic fibers and possibly additional additive substances, such as opacifiers, has a portion by weight between about 10 and 30% of the flexible ceramic in the form of fibers with a length of more than 10 mm with a comparatively high bulk density of about 200 to 250 kg/m.sup.3, especially of about 350 kg/m.sup.3. Although no binder such as e.g. phenol resin is contained therein, said flexible ceramic in the case of a given high content of long fibers, has a high bending strength, but at the same time it is very resistant to breakage in the case even of multiple bendings around relatively small bending radii.

Abstract: The formation of carbon on metals exposed to hydrocarbons in a thermal cracking process is reduced by contacting such metals with a halogen containing silicon compound selected from the group consisting of halogen containing silanes, halogen containing disilanes, and halogen containing siloxanes. After the metals are contacted with the halogen containing silicon compound, the halogen containing silicon compound is converted to silicon dioxide to form a protective coating on the metals. This protective coating substantially reduces the formation of carbon on metals exposed to hydrocarbons in a thermal cracking process.

Abstract: A process for defluorination of a fluoride-containing fumed silica, which comprises entraining the silica in a high velocity stream of steam at an elevated temperature for a few seconds and then separating the defluorinated silica from the steam, thereby obtaining a fumed silica product with a substantially reduced fluoride content.

Abstract: The residual gas obtained in the pyrogenic production of metal oxides or metalloid oxides contain besides the desired product elemental chlorine if a chlorine containing starting material is employed. After cooling the residual gas the elemental chlorine is reacted to form hydrogen chloride by using an aqueous solution of a reducing agent and in this form the chlorine is subsequently washed out of the residual gas.

Abstract: There is provided a pyrogenic process for the production of finely divided oxide of a metal and/or a metalloid in which there is employed as the starting material a vaporizable halogen compound of a metal and/or metalloid. Because of the starting material there is formed elemental halogen which is an impurity in the oxide formed. To remove the halogen there is supplied to the cooling section of the production plant a mixture of hydrogen and inert gas.

Abstract: There is prepared pyrogenically produced silicon dioxide-mixed oxide having a BET surface area of 50 to 400 m.sup.2 /g which contains as a constituent of the mixed oxide:0.01 to 10 weight % zirconium dioxide or0.01 to 10 weight % iron oxide (ferric oxide) or0.01 to 9.9 weight % titanium dioxide.Because of the doping with the foreign oxide the silicon dioxide-mixed oxide is more temperature stable than the undoped silicon dioxide. The product can be used as thermal insulation either as unpressed material in free bulk form or as a compacted mixture.

Abstract: There is disclosed an improved process and apparatus for the production of finely-divided metal and metalloid oxides by flame hydrolysis of corresponding metal and metalloid halides whereby fouling of burner apparatus is substantially completely avoided.

Abstract: In an improved process for the production of a finely divided oxide of a metal, silicon or mixtures thereof by the hydrolytic conversion of a corresponding volatile chloride of said metal, silicon or mixtures thereof in a flame; wherein said volatile chloride or said mixture of volatile chlorides in admixture with a combustible hydrogen-containing gas and air or oxygen are fed to a flame emitting from a burner into a reaction chamber to thereby form an oxide aerosol in waste gases from said burner; cooling said oxide and said waste gases; and separating said oxide from said waste gases; wherein the improvement comprises maintaining said waste gases substantially free of chlorine by reducing chlorine that forms during said conversion in said flame with hydrogen while cooling said waste gas below the temperature at which hydrogen and oxygen react in said waste gas.

Abstract: In case of the pyrogenous production of metal oxides or metalloid oxides, whenever a halogen compound is used as a starting material, an elementary halogen is formed as a byproduct. This may be converted in the cooling section of the reaction apparatus with hydrogen into hydrogen halide.For a better temperature control and prevention of uncontrolled deflagration of the hydrogen in case of the halogen detonating gas reaction, according to the invention the hydrogen is introduced into the cooling section by means of a double jacket pipe, whereby an inert gas is introduced additionally by way of the interstice between the inside wall and the outside jacket of the double jacket pipe into the cooling section.

Abstract: A process for working up hydrolyzable and/or water-soluble compounds by ping them in water is provided wherein the compounds are fed into the funnel of a rotating cone of water running down into the tip of the cone, with the water being constantly renewed by a supply at the base of the cone. The process is particularly useful for working up mixtures containing silanes and/or chlorosilanes in silicon deposition plants.

Abstract: Process for the preparation of a porous, pure silica which is particularly suitable as a catalyst support for a chromium-oxide catalyst used in polymerizing of olefins. The process comprises the steps of converting a silicon-halogen compound to a silica and then admixing with water to form a silica gel. The gel is then spray-dried to achieve the required particle size and pore volume.The silica can then be made into a catalyst by placing on the support a chromium compound and then heating in a non-reducing atmosphere.

Abstract: Process for the preparation of a porous, pure silica which is particularly suitable as a catalyst support for a chromium-oxide catalyst used in polymerizing of olefins. The process comprises the steps of converting a silicon-halogen compound to a silica and then admixing with water to form a silica gel. The gel is then dried and ground to a predetermined particle size. The silica can then be made into a catalyst by placing on the support a chromium compound and then heating in a non-reducing atmosphere.

Abstract: Process for the preparation of a porous, pure silica which is particularly suitable as a catalyst support for a chromium-oxide catalyst used in polymerizing of olefins. The process comprises the steps of converting a silicon-halogen compound to a silica and then admixing with water to form a silica gel. The gel is then spray-dried to achieve the required particle size and pore volume.The silica can then be made into a catalyst by placing on the support a chromium compound and then heating in a non-reducing atmosphere.

Abstract: Process for the preparation of a porous, pure silica which is particularly suitable as a catalyst support for a chromium-oxide catalyst used in polymerizing of olefins. The process comprises the steps of converting a silicon-halogen compound to a silica and then admixing with water to form a silica gel. The gel is then dried and ground to a predetermined particle size. The silica can then be made into a catalyst by placing on the support a chromium compound and then heating in a non-reducing atmosphere.

Abstract: A process for treatment of aluminum chloride production offgas containing Cl.sub.2, CO, CO.sub.2, HCl, COCl.sub.2, COS, SO.sub.2, N.sub.2, SiCl.sub.4 and metal chlorides by reaction with water vapor in the presence of an alumina or low iron sand catalyst to convert SiCl.sub.4 and metal chlorides to the corresponding oxides and HCl; subsequent reaction of COCl.sub.2 with water vapor in the presence of an activated carbon catalyst to form CO.sub.2 and HCl; and removal of HCl by contacting the offgas with liquid water. Reaction with steam in the presence of alumina catalyst prior to reaction with steam in the presence of an activated carbon catalyst prolongs the useful life of the activated carbon catalyst and avoids the necessity of removing SiCl.sub.4 and metal chlorides from the offgas by adsorption onto dry activated carbon prior to contacting the activated carbon catalyst with offgas.

Abstract: The method resides in that silicon tetrafluoride is subjected to water hydrolysis in the presence of sulphuric acid, the reactants being in an aerosol state.Hydrolysis is performed at a volume ratio of silicon tetrafluoride to sulphuric acid equal to 40:1-80:1, concentration of sulphuric acid within the range of 45-73 wt. %, and the rate of silicon tetrafluoride flow in the reaction zone of 0.2-4.0 m/sec. The process is run at room temperature and atmospheric pressure.As a result of hydrolysis, silicon dioxide and fluorine-containing sulphuric acid solution are obtained, hydrogen fluoride being extracted from the solution upon heating.The proposed invention makes possible an effective use of silicon tetrafluoride with maximum conversion of the components thereof into end products, separation of the end products taking place simultaneously with the formation thereof. The yield of the products reaches 92-95 wt. % of their content in the initial raw material.

Abstract: A process for the manufacture of highly dispersed silicon dioxide with improved thickening action by treatment of pyrogenically produced silicic acid comprising the following steps:A. preparing silicic acid by flame hydrolysis from silicon halides;B. separating the silicic acid from generated gases;C. reating the acid with 2 to 10 percent by weight of silicon tetrachloride calculated on silicic acid, while optionally/mechanically stirring;D. hydrolyzing the product by means of an air/water vapor mixture, and finally deacifying to obtain the silicon dioxide of improved thickening action.The invention also relates to the thickening agent, which is useful for a variety of purposes, among others as additive for preparations of dental hygiene.

Abstract: A method of producing high-purity transparent vitreous silica body through flame hydrolysis of high-purity silane type gas, comprising forming the width in the sectional direction of the reduction area of said flame so as to be about more than 1.5 times as against the diameter of the formed vitreous silica body, and the length of the reduction area of said flame so as to be about more than 2.5 times as against said diameter, while retaining the head portion of the formed vitreous silica body within the reduction area of said flame to synthesize the high-purity transparent vitreous silica body.

Abstract: A process and device for the manufacture of highly disperse silicon dioxide by reacting gaseous organosilanes and other gases that burn with formation of water with oxygen-containing gases in a flame which comprises evaporating the organosilane in an evaporator in such a manner that the level of liquid organosilane is held constant at an organosilane evaporatinng vapor pressure of 0.2 to 1.2 atmospheres gage and, at most, at a temperature of 45.degree. C, preferably 20.degree. to 35.degree. C, above the boiling point of the particular organosilane, maintaining the temperature of the vapor until mixing with the other gases occurs, metering the gas mixture resulting from the mixing through a cone-shaped inlet into a combustion chamber, flushing oxygen-containing gases through an annular nozzle surrounding the inlet into the combustion chamber, and indirectly but positively, cooling the latter.

Abstract: Hydrogenation-dehydrogenation of suitable feedstock is provided wherein such feedstock is subjected to hydrogenation-dehydration conditions in the presence of a catalytic amount of a solid containing, at least in part, a synthetic amorphous solid prepared by hydrolyzing and polymerizing in the presence of water a silane having the formula R(Si)X.sub.3, wherein R is a nonhydrolyzable organic group, X is a hydrolyzable group and (Si) is selected from the group consisting of ##STR1## AND ##STR2## AND CALCINING THE POLYMERIZED PRODUCT, SAID SILANE BEING ADMIXED WITH A SECOND COMPOUND, R'.sub.n MY.sub.m, wherein R' is selected from the group consisting of the same groups as R, Y is selected from the group consisting of the same groups as X and oxygen, M is at least one member selected from the group consisting of the elements of Groups IIIA, IVA, IVB, VA, VB, VIB, VIIB and VIII of the Periodic Table, m is any number greater than 0 and up to 8 and n is from 0 to any number less than 8.

Abstract: Process for the production of finely divided silicon dioxide having a surface of more than about 380 m.sup.2 /g BET which comprises converting a volatile silicon halide in an inert gas vehicle with a gas forming water upon combustion and oxygen gas or air in a flame, the quantity of oxygen being sufficient for the practically complete combustion of the combustible gas, and the quantities of oxygen or air and combustible gas being sufficient to produce a quantity of water which will at least suffice for the hydrolysis of the volatile silicon halide, said volatile silicon halide consisting essentially of trichlorosilane and said inert gas vehicle consisting for instance of nitrogen, carbon dioxide, noble gases or others the amount of trichlorosilane vapor being about 410-565 g trichlorosilane vapor per Nm.sup.3 /h total gas, the molar ratio of trichlorosilane vapor to nitrogen being about 0.5:1 - 5:1, the molar ratio of hydrogen in the combustible gas to oxygen being about 0.5:1 - 1.

Abstract: Fluorosilicic acid solutions, which normally undergo decomposition when distilled, thereby creating unwanted forms of SiO.sub.2, are rendered stable during distillation by providing in the fluorosilicic acid solution an amount of HF which is at least about 10 parts of HF per 36 parts of H.sub.2 SiF.sub.6 and an amount of H.sub.2 O which is at least about 54 parts of H.sub.2 O per 36 parts of H.sub.2 SiF.sub.6. The mixture is distilled to remove any excess H.sub.2 O and excess HF that is present, without encountering formation of SiO.sub.2, until an azeotropic solution containing about 36% H.sub.2 SiF.sub.6, about 10% HF and about 54% H.sub.2 O is reached. The ternary azeotrope, being of constant quality and concentration, is more suitable for use in various processes, such as processes for making fumed SiO.sub.2, than H.sub.2 SiF.sub.6 solutions which are not of constant quality or concentration.

Abstract: Novel amorphous siliceous materials having shape-selective sorption properties are prepared by a novel process of (1) hydrolyzing an organosilicon compound of the formula R[Si]X.sub.3 alone or in the presence of one or more compounds either of the formula R'.sub.n MY.sub.m, wherein R and R' are non-hydrolyzable organic groups, X is a hydrolyzable group, Y is the same as X or oxygen, [Si] is silicon or ##STR1## M is metal or non-metal, including silicon, of any group of the Periodic Table other than IA, IIA, VIIA or O, m is a number over 0 and up to 8 and n is 0 or a number less than 8, or an inorganic compound consisting of an anionic portion made up of M and Y and a cationic portion of either hydrogen, alkali or alkaline earth metal or ammonium; (2) effecting condensation polymerization of the hydrolyzed product; and (3) calcining the resulting polymerized product to convert all the R and R' groups to hydroxy or hydrogen.

Abstract: There is provided a process and apparatus for the production of finely-divided metal and metalloid oxides by flame hydrolysis of corresponding metal and metalloid halides whereby burner fouling is minimized and burner fabrication is facilitated by transpiration of a fuel gas or vapor along the boundaries of each halide-containing stream as it is discharged from the burner into a reaction zone.

Abstract: A method of producing high-purity transparent vitreous silica by supplying to a burner a high-purity silane type gas, and an inert gas, hydrogen gas and oxygen gas to effect the flame hydrolysis, comprising growing highly pure transparent vitreous silica at a controlled atmosphere of said flame that may increase the oxygen defect concentration of the vitreous silica, and thereafter heat-treating said formed body.

Abstract: Method and apparatus for the production of high purity hydrogen fluoride by the flame hydrolysis of silicon tetrafluoride and the deliberate cooling of the silicon dioxide and hydrogen fluoride reaction products without appreciable dilution to promote agglomeration of the silicon dioxide and permit separation of the hydrogen fluoride with substantially no contamination.

Abstract: Novel amorphous siliceous materials having shape-selective sorption properties are prepared by a novel process of (1) hydrolyzing an organosilicon compound of the formula R[Si]X.sub.3 alone or in the presence of one or more compounds either of the formula R'.sub.n MY.sub.m, wherein R and R' are non-hydrolyzable organic groups, X is a hydrolyzable group, Y is the same as X or oxygen, [Si] is silicon or --Si(R).sub.2 --O--Si , M is metal or non-metal, including silicon, of any group of the Periodic Table other than IA, IIA, VIIA or O, m is a number over 0 and up to 8 and n is 0 or a number less than 8, or an inorganic compound consisting of an anionic portion made up of M and y and a cationic portion of either hydrogen, alkali or alkaline earth metal or ammonium; (2) effecting condensation polymerization of the hydrolyzed product; and (3) calcining the resulting polymerized product to convert all the R and R' groups to hydroxy or hydrogen.

Abstract: Process for the production of a finely divided oxide of a metal or silicon by the hydrolytic conversion of a volatile corresponding metal halide or silicon halide in a flame, said process comprising feeding the volatile halide in a mixture with a combustible hydrogen-containing gas and air or oxygen to a burner provided with a mouth emitting a flame, burning the mixture in a fire tube to form a first portion of water vapor, said burner surrounded by an annular chamber forming a nozzle through which hydrogen is passed to keep the mouth of the burner free of attachments of solid substances, the quantity of oxygen or air being sufficient for the practically complete combustion of the combustible gas, and the quantities of oxygen or air and combustible gas being sufficient to produce the first portion of water vapor which will at least suffice for the hydrolysis of the volatile halides, and further wherein said flame is allowed to burn in an atmosphere consisting of gases containing a second portion of water vapo