Abstract: A siloxane composition, comprising from 70 to 99 parts by weight of a solid particulate having a median particle size of from 0.1 to 3000 ?m and from 1 to 30 parts by weight of a binder having a median particle size of from 5 to 250 ?m, wherein the composition is a powder and the binder comprises a siloxane resin having the formula: (R13SiO1/2)w(R12SiO2/2)x(R1SiO3/2)y(SiO4/2)z, wherein each R1 is independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, —O?NR2R3, —OR2, —O—R4—OR2, and an epoxy-substituted organic group, wherein R2 is C1 to C8 hydrocarbyl, R3 is R2 or —H, R4 is hydrocarbylene, w+x+y+z=1, y/(w+x+y+z) is at least 0.67, and the siloxane resin has a softening point of from 30 to 115° C.; an agglomerate, and a method preparing the agglomerate.

Abstract: Metallurgical grade silicon is purified by removing metallic impurities and non-metallic impurities. The object is to produce a silicon species that is suitable for use as solar grade silicon. The process involves grinding metallurgical grade silicon containing metallic and non-metallic impurities to a silicon powder consisting of particles of silicon having a diameter of less than about 5 millimeter. While maintaining the ground silicon powder in the solid state, the ground silicon powder is heated to a temperature less than the melting point of silicon (1410° C.) under reduced pressure. The heated ground silicon powder is maintained at that temperature for a period of time sufficient to enable at least one metallic or non-metallic impurity to be removed from the metallurgical grade silicon.

Abstract: This invention relates to the preparation of polycrystalline silicon carbide fibers from ceramic fiber. The process involves heating the ceramic fiber in an environment containing a volatile sintering aid to a temperature sufficient to convert the ceramic fiber to the polycrystalline silicon carbide fiber.

Abstract: Ceramic SiCO fibers are formed by spinning a mixture of a substantially linear polysiloxane fluid having unsaturated hydrocarbon substituents and a photoinitiator into a fiber, exposing the fiber to radiation, and heating the fiber in an inert environment to a temperature above about 800.degree. C.

Abstract: This invention relates to the preparation of polycrystalline silicon carbide fibers from ceramic fibers. The process involves heating the ceramic fiber in an environment containing a volatile sintering aid to a temperature sufficient to convert the ceramic fiber to the polycrystalline silicon carbide fiber.

Abstract: A process for the preparation of substantially polycrystalline silicon carbide fibers is provided. The fibers may be fabricated to have a small diameter and are thermally stable at high temperatures. The process is carried out by initially forming fibers from a preceramic polymeric precursor comprising methylpolydisilylazane resins. The fibers are then infusibilized to render them nonmelting followed by a pyrolysis step in which the fibers are heated to a temperature in excess of 1600.degree. C. in a nonoxidizing atmosphere to form substantially polycrystalline silicon carbide fibers. The substantially polycrystalline silicon carbide fibers which are formed by the process of the present invention have at least 75% crystallinity and have a density of at least about 2.9 gm/cc.The polymeric precursor or the fibers contain, or have incorporated therein, at least about 0.2% by weight boron.

Abstract: The present invention relates to ceramic fibers of the Si-C-N-O series with a diameter less than about 20 micrometers. It has been unexpectedly found that the thermal stability of these fibers can be increased by minimizing the impurity content, primarily the content of metals or metallic compounds. Such fibers with low levels of contaminants retain greater than about 60 percent of their initial tensile strength when subjected to temperatures of 1300.degree.-1400.degree. C. for at least 30 minutes in a non-oxidative environment.

Abstract: A process for the preparation of substantially polycrystalline silicon carbide fibers are provided. The fibers may be fabricated to have a small diameter and are thermally stable at high temperature. The process is carried out by initially forming fibers from a preceramic polymeric precursor comprising phenyl-containing polyorganosiloxane resins. The fibers are then infusibilized to render them nonmelting followed by a pyrolysis step in which the fibers are heated to a temperature in excess of 1600.degree. C. in a nonoxidizing atmosphere to form substantially polycrystalline silicon carbide fibers. The substantially polycrystalline silicon carbide fibers which are formed have at least 75% crystallinity and have a density of at least about 2.9 gm/cm.sup.3. The polymeric precursor or the fibers contain, or have incorporated therein, at least about 0.2 % by weight boron.

Abstract: The elastic modulus and density of an amorphous, ceramic article derived from a resinous organosilicon polymer and having a composition consisting essentially of silicon, nitrogen and/or carbon are increased while substantially maintaining or improving tensile strength by heat treating the ceramic article at an elevated temperature under superatmospheric nitrogen pressure to increase its density while avoiding crystallization. During heat treatment, at least some of the conditions of time, temperature, heating rate, cooling rate, pressure and atmosphere are controlled to minimize erosion of the article which could otherwise occur due to the loss to the surrounding atmosphere, as a gas or gaseous component, of at least one of nitrogen, silicon and carbon. The heat treated, ceramic article is amorphous and non-crystalline and has a density substantially greater than 2.5 g/cc together with desirable values of tensile strength and elastic modulus.

Abstract: A rapid method of infusibilizing (curing) preceramic polymers comprising treatment said polymers with gaseous nitrogen dioxide. The infusibilized polymers may be pyrolyzed to temperatures in excess of about 800.degree. C. to yield ceramic materials with low oxygen content and, thus, good thermal stability. The methods are especially useful for the production of ceramic fibers and, more specifically, to the on-line production of ceramic fibers.

Abstract: The elastic modulus and density of an amorphous, ceramic article derived from a resinous organosilicon polymer and having a composition consisting essentially of silicon, nitrogen and/or carbon are increased while substantially maintaining or improving tensile strength by heat treating the ceramic article at an elevated temperature under superatmospheric nitrogen pressure to increase its density while avoiding crystallization. During heat treatment, at least some of the conditions of time, temperature, heating rate, cooling rate, pressure and atmosphere are controlled to minimize erosion of the article which could otherwise occur due to the loss to the surrounding atmosphere, as a gas or gaseous component, of at least one of nitrogen, silicon and carbon. The heat treated, ceramic article is amorphous and non-crystalline and has a density substantially greater than 2.5 g/cc together with desirable values of tensile strength and elastic modulus.

Abstract: A process for preparing ceramic materials with reduced carbon levels is described. The process involves treating a silicon-containing preceramic polymer with ammonia at a temperature of 550.degree.-800.degree. C. for a time sufficient to reduce the carbon content prior to pyrolysis at 900.degree.-1500.degree. C. Another process also involves the pyrolysis of a silicon-containing preceramic polymer in an ammonia atmosphere. The carbon level of ceramic materials produced by this invention can be controlled to a given, desired level by varying the process conditions. Suitable silicon-containing preceramic polymers include polycarbosilanes, polysilazanes, polysilanes, organosilsesquioxane-containing sol-gels, and organopolysiloxanes which are capable of being converted to ceramic materials when fired to elevated temperatures. Ceramic fibers can be prepared by the processes disclosed which contain less than 0.25 weight percent carbon.

Abstract: A method of producing elastomeric silicone foams from a two-part system is disclosed. The method mixes the ingredients then allows a froth to form and cure at ambient temperature to an elastomeric silicone foam. The method mixes a vinyl-containing polydiorganosiloxane (1), a hydroxylated polydiorganosiloxane (2), a platinum catalyst (3), an organohydrogensiloxane (4) and a profoamer (5). The profoamer is a resinous, benzene-soluble organosiloxane copolymer consisting essentially of SiO.sub.4/2 units, silicone bonded hydroxyl groups, (CH.sub.3).sub.3 SiO.sub.1/2 units, and fluorine-containing units. An embodiment of the method includes a liquified blowing agent and stores the mixture under superatmospheric pressure, forming a foam by releasing the mixture to atmospheric pressure. Another embodiment includes an alcohol in the mixture to provide a foam of lower density.

Abstract: A method of producing elastomeric silicone foams from a two-part system is disclosed. The method mixes the ingredients then allows a froth to form and cure at ambient temperature to an elastomeric silicone foam. The method mixes a vinyl-containing polydiorganosiloxane (1), a hydroxylated polydiorganosiloxane (2), a platinum catalyst (3), an organohydrogensiloxane (4) and a profoamer (5). The profoamer is a resinous, benzene-soluble organosiloxane copolymer consisting essentially of SiO.sub.4/2 units, silicone bonded hydroxyl groups, (CH.sub.3).sub.3 SiO.sub.1/2 units, and fluorine-containing units. An embodiment of the method includes a liquified blowing agent and stores the mixture under superatmospheric pressure, forming a foam by releasing the mixture to atmospheric pressure. Another embodiment includes an alcohol in the mixture to provide a foam of lower density.

Abstract: A composition useful in producing an open-cell, elastomeric silicone foam combines a silicone oil-in-water emulsion, which forms an elastomer upon removal of the water, with an aerosol propellant. When the composition is discharged to atmospheric pressure, a froth is formed. Removing water from the froth yields an open-cell foam. The froth is stabilized by surfactants, thickeners, or froth stabilizers selected from fibers or lauryl alcohol.

Abstract: Polyorganosiloxane foams exhibiting a desirable combination of low density, an average cell size below 4 mm. and an average cell concentration greater than 4 per linear centimeter are obtained by dispensing oxygen curable mercaptoorganosiloxane compositions containing a cobaltocene catalyst, a dispersed liquid or gaseous blowing agent and, as a foam stabilizer, a resinous organosiloxane copolymer comprising trimethylsiloxy units, SiO.sub.4/2 units and specified fluorine-containing organosiloxane units. The polymer portion of the composition includes at least one polyorganosiloxane containing at least 20 mole percent of dimethylsiloxane units and an average of more than 2 mercaptoalkyl or mercaptoalkylene groups per molecule.

Abstract: A composition useful in producing an open-cell, elastomeric silicone foam combines a silicone oil-in-water emulsion, which forms an elastomer upon removal of the water, with an aerosol propellant. When the composition is discharged to atmospheric pressure, a froth is formed. Removing water from the froth yields an open-cell foam. The froth is stabilized by surfactants, thickeners, or froth stabilizers selected from fibers or lauryl alcohol.

Abstract: Polyorganosiloxane foams are prepared by the volatilization of a blowing agent within a polyorganosiloxane composition that is curable by a hydrosilation reaction and includes as a foam stabilizer a resinous polyorganosiloxane comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing siloxane units.

Abstract: Polyorganosiloxane foams are prepared by the volatilization of a blowing agent within a polyorganosiloxane composition that is curable by a hydrosilation reaction and includes as a foam stabilizer a resinous polyorganosiloxane comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing siloxane units.

Abstract: Polyorganosiloxane foams are obtained by blending, dispensing and curing two-part polyorganosiloxane compositions comprising a liquid hydroxyl endblocked polydimethylsiloxane, a liquid alkyl orthosilicate as the curing agent, a catalytically effective amount of a tin compound, a blowing agent and, as a foam stablilizer, a resinous organosiloxane copolymer comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing organosiloxane units.