Patents by Inventor Jonathan Lipowitz
Jonathan Lipowitz has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6261509Abstract: A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.Type: GrantFiled: April 3, 2000Date of Patent: July 17, 2001Assignee: Dow Corning CorporationInventors: Thomas Duncan Barnard, Jonathan Lipowitz, Kimmai Thi Nguyen
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Patent number: 6129887Abstract: A process for producing polycrystalline silicon carbide includes heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.Type: GrantFiled: August 26, 1998Date of Patent: October 10, 2000Assignee: Dow Corning CorporationInventors: Thomas Duncan Barnard, Jonathan Lipowitz, Kimmai Thi Nguyen
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Patent number: 5840242Abstract: The present invention relates to a method for preparing a ceramic fiber from alkenyl or alkynyl functional resins and to the ceramic fibers produced therefrom. The method comprises (A) forming a fiber from a siloxane resin comprised of R.sup.1.sub.a R.sup.2.sub.b RSiO.sub.(3-a-b)/2 units wherein R is an unsaturated carbon group; each R.sup.1 is selected from the group consisting essentially of an aryl group having from 6 to 10 carbon atoms and functional derivatives thereof; each R.sup.2 is selected from the group consisting essentially of an alkyl group having from 1 to 4 carbon atoms and functional derivatives thereof; a has a value of 0, 1 or 2; b has a value of 0, 1, or 2 with the proviso that a+b <2; (B) curing the fiber by exposing the fiber to high energy radiation to render it non-fusible; and (C) heating the non-fusible fiber in an inert environment to a temperature above about 800.degree. C. to convert it to a ceramic fiber.Type: GrantFiled: April 22, 1997Date of Patent: November 24, 1998Assignee: Dow Corning CorporationInventors: William Henry Atwell, Duane Ray Bujalski, Jonathan Lipowitz, Kai Su, Gregg Alan Zank
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Patent number: 5707568Abstract: 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 methylpolysilane 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/cm.sup.3. The polymeric precursor or the fibers contain, or have incorporated therein, at least about 0.2% by weight boron.Type: GrantFiled: December 18, 1989Date of Patent: January 13, 1998Assignee: Dow Corning CorporationInventors: David Charles Deleeuw, Jonathan Lipowitz, Paul Pu-yuan Lu, James Alan Rabe
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Patent number: 5436207Abstract: Disclosed is a process for the formation of silicon carbide powder in which vaporized polysiloxanes are reacted and pyrolyzed in a single heating step to form the silicon carbide powder. The process is simple and inexpensive and yields powder having desirable characteristics.Type: GrantFiled: December 10, 1993Date of Patent: July 25, 1995Assignee: Dow Corning CorporationInventors: William H. Atwell, Donald M. Bartos, Patrick J. Harder, Jonathan Lipowitz, Chandan K. Saha
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Patent number: 5366943Abstract: 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.Type: GrantFiled: September 10, 1993Date of Patent: November 22, 1994Assignee: Dow Corning CorporationInventors: Jonathan Lipowitz, James A. Rabe
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Patent number: 5279780Abstract: 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.Type: GrantFiled: July 22, 1992Date of Patent: January 18, 1994Assignee: Dow Corning CorporationInventors: Jonathan Lipowitz, James A. Rabe
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Patent number: 5268336Abstract: 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.Type: GrantFiled: June 18, 1990Date of Patent: December 7, 1993Assignee: Dow Corning CorporationInventors: David C. Deleeuw, Jonathan Lipowitz, James A. Rabe
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Patent number: 5238742Abstract: 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.Type: GrantFiled: December 16, 1991Date of Patent: August 24, 1993Assignee: Dow Corning CorporationInventors: Harvey A. Freeman, Neal R. Langley, Chi-Tang Li, Jonathan Lipowitz, James A. Rabe
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Patent number: 5167881Abstract: 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.Type: GrantFiled: January 31, 1991Date of Patent: December 1, 1992Assignee: The Dow Corning CorporationInventors: William H. Atwell, Duane R. Bujalski, Eric J. Joffre, Gary E. LeGrow, Jonathan Lipowitz, James A. Rabe
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Patent number: 5162269Abstract: This invention relates to the preparation of thermally stable, substantially polycrystalline silicon carbide ceramic fibers derived from a polycarbosilane resin. The unexpected thermal stability of these fibers is achieved by the incorporation of boron prior to ceramification.Type: GrantFiled: July 15, 1991Date of Patent: November 10, 1992Assignee: Dow Corning CorporationInventors: David C. Deleeuw, Jonathan Lipowitz, Paul P. Lu
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Patent number: 5135809Abstract: 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.Type: GrantFiled: September 27, 1989Date of Patent: August 4, 1992Assignee: Dow Corning CorporationInventors: James A. Rabe, Jonathan Lipowitz, Richard E. Jones
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Patent number: 5071600Abstract: This invention relates to the preparation of thermally stable, substantially polycrystalline silicon carbide ceramic fibers derived from a polycarbosilane resin. The unexpected thermal stability of these fibers is achieved by the incorporation of boron prior to ceramification.Type: GrantFiled: January 16, 1990Date of Patent: December 10, 1991Assignee: Dow Corning CorporationInventors: David C. Deleeuw, Jonathan Lipowitz, Paul P. Lu
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Patent number: 5051215Abstract: 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.Type: GrantFiled: March 21, 1990Date of Patent: September 24, 1991Assignee: Dow Corning CorporationInventors: James A. Rabe, Jonathan Lipowitz, Paul P. Lu
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Patent number: 4921657Abstract: 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.Type: GrantFiled: November 13, 1987Date of Patent: May 1, 1990Assignee: Dow Corning CorporationInventors: James A. Rabe, Jonathan Lipowitz, Richard E. Jones
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Patent number: 4889899Abstract: A method is described to prepare preceramic polysilanes which contain at least one weight percent vinyl. To ensure the survival of the vinyl groups in the polysilane the reaction and process conditions must be carefully controlled. The vinyl-containing polysilanes can be formed into fibers, cured either thermally or by UV irradiation, and then pyrolyzed to form ceramic fibers. Thermal curing and pyrolysis can be combined into a single process step.Type: GrantFiled: September 8, 1987Date of Patent: December 26, 1989Assignee: Dow Corning CorporationInventors: Duane R. Bujalski, Gary E. Le Grow, Jonathan Lipowitz, Thomas F. Lim
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Patent number: 4824918Abstract: Vinyl-containing polysilanes are described wherein the vinyl groups are attached to endblocking sites of intermediate reactivity. These vinyl-containing polysilanes are prepared by reacting a halogen-endblocked polysilane with, first, a non-vinyl-containing Grignard reagent or a non-vinyl organolithium compound whereby the most reactive halogen endblocking groups are replaced; then, second, reacting the resulting polysilane with vinyl Grignard reagent or vinyllithium whereby the halogen endblocking groups of intermediate reactivity are replaced; and, third, reacting the resulting polysilane with a non-vinyl-containing Grignard reagent or a non-vinyl organolithium compound whereby the least reactive halogen endblocking groups are replaced. The vinyl-containing polysilanes can be coverted to ceramic materials, including ceramic fibers, by pyrolysis.Type: GrantFiled: September 4, 1987Date of Patent: April 25, 1989Assignee: Dow Corning CorporationInventors: Duane R. Bujalski, Gary E. LeGrow, Jonathan Lipowitz, Thomas F. Lim
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Patent number: 4743662Abstract: What is disclosed is a method of rendering shaped preceramic polymers infusible prior to the pyrolysis of such polymers by treating the shaped preceramic polymer with a plasma.Type: GrantFiled: November 3, 1986Date of Patent: May 10, 1988Assignee: Dow Corning CorporationInventor: Jonathan Lipowitz
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Patent number: 4486567Abstract: Hydroxyl-endblocked polydiorganosiloxane oligomer is polymerized through the use of a catalyst mixture of quaternary ammonium carboxylate and carboxylic acid. The method heats the mixture of oligomer and catalyst to a temperature in the range of from 90.degree. C. to 150.degree. C., removing water from the mixture, until the desired degree of condensation is achieved. When cooled, the product is a stable polydiorganosiloxane of increased molecular weight. The catalyst can be inactivated by heating and removing volatile byproducts. One embodiment of the method adds an acidic or neutral reinforcing filler to the mixture before polymerization to yield a storage stable silicone polymer-filler mixture which is useful in a manner similar to conventionally produced silicone polymer-filler mixtures.Type: GrantFiled: March 14, 1983Date of Patent: December 4, 1984Assignee: Dow Corning CorporationInventors: Sheryl A. Bowman, James R. Falender, Jonathan Lipowitz, John C. Saam
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Patent number: 4472556Abstract: A method is disclosed for enhancing at least one of the mechanical properties of a partially crystalline thermoplastic by forming a dispersion of a polydiorganosiloxane within the thermoplastic, and extending the resultant dispersion. Ultimate tensile strength, modulus, and ultimate elongation can be enhanced in comparison with the same thermoplastic with no added polydiorganosiloxane and no extension.Type: GrantFiled: December 20, 1982Date of Patent: September 18, 1984Assignee: Dow Corning CorporationInventors: Jonathan Lipowitz, Robert E. Kalinowski