Abstract: A throttle body assembly for a combustion engine includes a throttle body having a pressure chamber including a supply of liquid fuel, and a throttle bore with an inlet through which air is received. A throttle valve is carried by the throttle body with a valve head movable relative to the throttle bore. A metering valve is coupled to the throttle body, and has a valve element that is movable between open and closed positions. A boost venturi is located in the throttle bore and has an inner passage that is open at both ends to the throttle bore. The boost venturi has an opening through which fuel flows into the inner passage when the valve element is in the open position, wherein fuel flows from the pressure chamber to the metering valve under the force of gravity or under a pressure of less than 6 psi.

Abstract: In various embodiments, provided are methods of refining silicon wherein impurities of different densities are separated and concentrated using centrifugal force, and controlled crystallization of molten silicon provides further purification through concentration of impurities at a solid/liquid interface.

Abstract: A method of hydrophobing fillers such as inorganic pigments, metal oxides, metal hydroxides, and silicate minerals, involves contacting a filler with an oxa-silacycloalkane, until hydroxyl functionality on the filler is replaced with carbinol functionality (i.e. .tbd.C--OH). The preferred oxa-silacycloalkane is 2,2,4-trimethyl-1-oxa-2-silacyclopentane.

Abstract: This invention relates to the preparation of a highly densified boron carbide ceramic body by the pyrolysis of a mixture comprising boron carbide powder and a preceramic organosilicon polymer selected from the group consisting of polysiloxanes, polysilazanes, polysilanes, metallopolysiloxanes and metallopolysilanes. Such highly densified ceramic bodies can be prepared by sintering under pressure or by utilizing a pressureless process.

Abstract: A method for preparing in situ reinforced silicone elastomers and the compositions prepared by the method. The method comprises forming a mixture comprising an end-functional diorganopolysiloxane; a stoichiometric excess of a hydrolyzable siloxane having hydrolyzable functionality described by formula--R.sup.2 SiQ.sub.3-b R.sub.b, were each R is independently selected from a group consisting of alkyls comprising one to six carbon atoms, alkenyls comprising two to six carbon atoms, and aryls, R.sup.2 is a divalent hydrocarbon radical comprising one to 12 carbon atoms, each Q is independently selected from a group consisting of hydroxy, acyloxys comprising one to six carbon atoms, alkoxys comprising one to six carbon atoms, and substituted alkoxys comprising one to six carbon atoms, and b=0 to 2; and a tin salt catalyst and contacting the mixture with water to effect curing. The resulting silicone elastomers are in situ reinforced to provide high strength.

Abstract: A method for preparing in situ reinforced silicone elastomers and the compositions prepared by the method. The method comprises forming a mixture comprising a diorganosiloxane polymer having reactive end-terminal functionality, a stoichiometric excess of a reactive siloxane selected from a group consisting of triorganosilyl endblocked reactive siloxanes and reactive cyclosiloxanes, and a tin salt catalyst and contacting the mixture with water to effect curing. The resulting silicone elastomers are in situ reinforced to provide high strength.

Abstract: The present invention is a method for the preparation of carbinol-functional organosiloxanes and carbinol-functional organosiloxane resins. The method comprises contacting a cyclic silyl ether with an organosiloxane or an organosiloxane resin at a temperature within a range of about 25.degree. C. to 150.degree. C. The method may be conducted in the presence of an inert organic solvent to facilitate dissolution and contact of the reactants.

Abstract: This invention provides polyorganooxothiazenes exhibiting levels of molecular weight and properties not heretofore achieved by similar polymers reported in the prior art. The sulfonimidates that are condensed to form the polymers are prepared using a novel reaction between an N-triorganosilylsulfonamide and a triorganodihalophosphorane to form the corresponding N-triorganosilylsulfonimidoyl halide that is subsequently reacted with a fluorinated alcohol or phenol to form the N-triorgano-silylsulfonimidate.

Abstract: This invention relates to the preparation of highly densified ceramic bodies by the pyrolysis of a mixture comprising a preceramic borosiloxane, silicon carbide powder, a curing agent for the borosiloxane, a crosslinking agent for the borosiloxane and, optionally, additional components to facilitate sintering. Such highly densified ceramic bodies can be prepared by sintering under pressure or by a pressureless sintering process.

Abstract: A method is disclosed for the preparation of ceramic materials or articles by the pyrolysis of preceramic polysilanes wherein the preceramic polysilanes are rendered infusible prior to pyrolysis by exposure to ultraviolet irradiation in the presence of a reactive gas selected from the group consisting of ethylene, 1,3-butadiene, 2-methyl-1,3-butadiene, 1,4-pentadiene, silane, chlorosilane, dichlorosilane, boron trichloride, oxygen and water mixture, acetylene, and tetravinylsilane. This method is especially suited for the preparation of ceramic fibers. The ceramic fiber's surface properties can be modified by the practice of this invention; for example, a ceramic fiber with a carbon rich surface layer can be obtained when 1,3-butadiene is used as the reactive gas.

Abstract: Polysilacyclobutasilazanes are reacted with chlorosilanes and/or chlorodisilanes and ammonia to provide silane-modified polysilacyclobutasilazanes having silacycles incorporated in the polymer, which silacycles are subseqentially used to cross-link the silazanes.

Abstract: The silacyclobutane functional polydiorganosiloxane copolymers of the invention have the following structure: ##STR1## wherein M is selected from ##STR2## wherein R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, and R.sup.f are independently monovalent radicals selected from the group consisting of hydrogen, hydrocarbon, or substituted hydrocarbon; m and x are integers of from 0 or more; n is equal to 1; and p is an integer greater than 0; with the proviso that there is at least one silacyclobutane group in the copolymer. The copolymer can be made by reacting a hydroxyl endblocked polydiorganosiloxane with either a difunctional chain extending silacyclobutane or with a monofunctional chain stopper, or a mixture of chain extender and chain stopper. The copolymer can be made into curable compositions by use of suitable catalyst.

Abstract: A process for the preparation of a methylpolysilane having a controlled carbon content is provided which includes the steps of heating together to form a reaction mixture at least one alkoxy-functional disilane selected from the group consisting of disilanes having two, three, and four alkoxy groups bonded to the silicon atoms, and mixtures thereof, with either an alkoxy-functional silane having at least one unsaturated substituent or an unsaturated hydrocarbon compound in an amount effective to increase the carbon content of the resulting polymer. The reaction is carried out in the presence of a catalyst which is a source of alkoxide ions. The methylpolysilane polymers produced may be pyrolyzed to form ceramic compositions having increased carbon contents. The ceramics may find use as films, fibers, and coatings, as well as the many other uses to which silicon carbide ceramics have heretofore been put.

Abstract: A process for the preparation of a methylpolysilane having a controllable rheology, including a controllable glass transition temperature is provided which includes the steps of heating together at least one alkoxy-functional disilane selected from the group consisting of disilane having three and four alkoxy groups bonded to the silicon atoms, and mixtures thereof, with an amount of a dialkoxy disilane effective to control the glass transition temperature of the resulting polymer within the range of from about 0.degree. to about 200.degree. C. The reaction is carried out in the presence of a catalyst which is a source of alkoxide ions to catalyze the redistribution reaction. The redistribution reaction produces oligomer and longer chain polymeric silanes having greater than seven silicon atoms in the polymer chain. Methylpolysilanes formed in accordance with the practice of the present invention may then be readily formed into fibers by a conventional spinning process.

Abstract: The preparation of highly densified ceramic bodies by the sintering of certain preceramic polysilazanes filled with silicon carbide powders, metal-containing sintering aids, and, optionally, polysilazane curing agents is described. Such highly densified ceramic bodies can be prepared by either a pressureless sintering process or a hot press sintering process. The compositions of this invention can be formed into desired shapes and then sintered to form ceramic, shaped bodies with high densities. One advantage of the present invention is that the green bodies have relative high strengths and thus can be easily handled and, if desired, machined before sintering. The preceramic polysilazanes useful in this invention must yield ceramic chars which contains free or excess carbon in addition to carbon in the form of silicon carbide upon pyrolysis to elevated temperatures.

Abstract: A process for the preparation of preceramic metallopolysilanes is described. The process consists of reacting polysilanes with metallic compounds from which can be generated open coordination sites associated with the metallic element. Such open coordination sites can be generated by the reduction of the metallic compound with an alkali metal reducing agent, or by heating a metallic compound which has thermally labile ligands, or by the UV irradiation of a carbonyl-containing metallic compound. The metals which can be incorporated into the polysilane include aluminum, boron, chromium, molybdenum, tungsten, titanium, zirconium, hafnium, vanadium, niobium, and tantalum. These metallopolysilanes are useful, when fired at high temperatures, to form metal-containing ceramic materials.

Abstract: Polysilacyclobutasilazanes are reacted with chlorosilanes and/or chlorodisilanes and ammonia to provide silane-modified polysilacyclobutasilazanes having silacycles incorporated in the polymer, which silacycles are subsequently used to cross-link the silazanes.

Abstract: The preparation of highly densified ceramic bodies by the sintering of certain organopolysiloxanes filled with silicon carbide powders, and metal-containing sintering aids is described. Such highly densified ceramic bodies can be prepared by either a pressureless sintering process or a hot press sintering process. The compositions of this invention can be formed into desired shapes and then sintered to form ceramic, shaped bodies with high densities. One advantage of the present invention is that the green bodies have relative high strengths and thus can be easily handles and, if desired, machined before sintered. The organopolysiloxanes useful in this invention must yield a ceramic char which contains free or excess carbon in addition to carbon in the form of silicon carbide upon pyrolysis to elevated temperatures.

Abstract: An improvement in pre-ceramic methylpolysilanes that utilizes the reaction of methylpolysilanes with multiple-unsaturated compounds to reduce the number of ternary and highly reduced silicon atoms in the polymer matrix. Polymers thus modified are generally easier to process into ceramic fibers than prior art methylpolysilanes.

Abstract: Polysilacyclobutasilazanes are reacted with chlorosilanes and/or chlorodisilanes and ammonia to provide silane-modified polysilacyclobutasilazanes having silacycles incorporated in the polymer, which silacycles are subsequently used to cross-link the silazanes.