Patents by Inventor Subhash D. Karmarkar
Subhash D. Karmarkar 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: 6129135Abstract: A predetermined quantity of a metal-matrix composite material is injected to a heating crucible along an angular infeed direction toward a location therein at which a vortex is formed by the blade of an agitator through which the material is stirred while being superheated above the melting temperature to a pouring temperature under which the melted material is transferred to a casting mold after surface skimming thereof to form a product having improved wear resistance properties.Type: GrantFiled: June 29, 1999Date of Patent: October 10, 2000Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, William A. May, James M. Kerr, William A. Ferrando, Scott M. Hoover
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Patent number: 6116328Abstract: Alumina tiles within aluminum framing jigs are fixedly positioned by lock ns within an internally coated mold for centrifugal casting within a block of an aluminum alloy material. Such jigs and the tiles framed therein are coated with silver before casting to prevent aluminum oxidation by heating of the aluminum material to a molten state for deposit into the mold. Bonding of the tiles and framing of the jigs with the aluminum material being cast is also enhanced by such silver coating.Type: GrantFiled: July 29, 1999Date of Patent: September 12, 2000Assignee: The United States of America as represented by the Secretary of the NavyInventors: Subhash D. Karmarkar, Amarnath P. Divecha, William J. Bruchey, Gerald Bulmash, James M. Kerr, William A. Ferrando
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Patent number: 6082436Abstract: The article is produced by prepositioning nonwoven reinforcement, coated h a bond enhancing compound inside of a centrifugal casting mold that is surface coated for protective shielding of the reinforcement. Molten matrix metal is then introduced into the mold while being rotated about its longitudinal axis until the molten metal completely encapsulates the reinforcement.Type: GrantFiled: January 28, 1999Date of Patent: July 4, 2000Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, Philip Hesse, William J. Bruchey
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Patent number: 5858460Abstract: Silver metal-coated boron carbide (B.sub.4 C) particle reinforce aluminumthium alloy or magnesium-lithium matrix composites which are prepared by coating the B.sub.4 C particles with molten AgNO.sub.3, decomposing the molten AgNO.sub.3 to form a coating of silver metal on the B.sub.4 C particles, mixing the silver coated B.sub.4 C particles into a molten aluminum-lithium alloy or magnesium-lithium alloy matrix, allowing the mixture to cool and solidify the solid composite.Type: GrantFiled: July 1, 1991Date of Patent: January 12, 1999Assignee: The United States of America as represented by the Secretary of the NavyInventors: William A. Ferrando, Amarnath P. Divecha, James Kerr, Subhash D. Karmarkar
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Patent number: 5509459Abstract: A process for forming pressure cast alumina tile reinforced aluminum alloy rmor in which a silver coated aluminum disc is first inserted into a mold assembly, the mold assembly includes a base plate, a hollow steel die with a removable steel liner located on the base plate, a plug disposed on the base plate within the die cavity, and a punch movably disposed within the die cavity, the aluminum disc being inserted within the die cavity over the plug. Next, an alumina tile preform is prepared by cutting a plurality of alumina tiles and weaving the tiles together with a stiff steel wire. The alumina tile preform is inserted over the silver coated aluminum disc in the cavity of mold assembly. The steel die, the plug and the disc are heated. The punch is also heated separately. A melt of molten aluminum is prepared and poured into the die cavity, completely covering the alumina tile preform. The heated punch is immediately driven into the cavity to apply pressure to the molten aluminum.Type: GrantFiled: September 28, 1994Date of Patent: April 23, 1996Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, Scott M. Hoover, James M. Kerr, William A. Ferrando
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Patent number: 5337803Abstract: The article is produced by prepositioning nonwoven reinforcement made of a etallic mesh to which ceramic tiles are wired inside of a centrifugal casting mold. Molten matrix metal is then introduced into the mold while being rotated about an axis parallel to the inflow path of the molten metal until it completely encapsulates the reinforcement.Type: GrantFiled: May 25, 1993Date of Patent: August 16, 1994Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, William A. Ferrando, Scott M. Hoover
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Patent number: 5295528Abstract: A reinforcement made of a composite material is positioned inside of a ceifugal casting mold. Molten matrix metal is then introduced into the mold while being rotated about its longitudinal axis until the molten metal completely encapsulates the reinforcement.Type: GrantFiled: May 17, 1991Date of Patent: March 22, 1994Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Diyecha, Subhash D. Karmarkar, William A. Ferrando, Scott M. Hoover
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Patent number: 5253797Abstract: A thin layer of silver metal is formed between a molybdenum surface and a eel surface. The silver metal layer is diffusion bonded to the molybdenum surface and diffusion bonded to the steel surface, thus bonding the molybdenum and steel surfaces together.Type: GrantFiled: July 21, 1992Date of Patent: October 19, 1993Assignee: The United States of America as represented by the Secretary of the NavyInventors: William A. Ferrando, Subhash D. Karmarkar, Scott M. Hoover, Amarnath P. Divecha
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Patent number: 5214234Abstract: A composite reinforced gun barrel with a composite of a titanium, nickel, FeCrAlY alloy matrix reinforced with round filaments or rectangular ribbons made of molybdenum or tungsten. The composite layer may be bonded directly onto the barrel or it may be bonded to a steel jacket which can then be heat shrunk onto an existing gun barrel.Type: GrantFiled: July 17, 1992Date of Patent: May 25, 1993Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, Scott M. Hoover, William A. Ferrando
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Patent number: 5193605Abstract: Process for the production of ingots of castable discontinuous metal matrix omposites by encapsulating particulate refractory material of the B.sub.4 C or SiC in a matrix metal of Li or al to form a solid master alloy, and introducing the master alloy into molten Mg or an alloy thereof, mixing and then cooling to solidify the resultant mixture and form an ingot with the refractory material substantially dispersed in the ingot.Type: GrantFiled: November 4, 1991Date of Patent: March 16, 1993Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, William A. Ferrando, Scott M. Hoover, James M. Kerr
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Patent number: 5051307Abstract: A process for producing high temperature, oxidation resistant silver metal oatings on carbon/carbon composite structures by coating the carbon/carbon surfaces with molten AgNO.sub.3 at a temperature above the melting point of AgNO.sub.3 but below the decomposition temperature of AgNO.sub.3, and then heating the resulting uniform coating of molten AgNO.sub.3 at a temperature of from the decomposition temperature of AgNO.sub.3 to about 700.degree. C. to decompose the molten AgNO.sub.3 and form a uniform coating of silver metal.Type: GrantFiled: July 3, 1990Date of Patent: September 24, 1991Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, William A. Ferrando, Philip W. Hesse, Subhash D. Karmarkar
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Patent number: 5025849Abstract: Tubes or other symmetrical shapes are formed of composite materials, such silicon carbide and aluminum, by spin casting. The reinforcing material can be precast into a billet or bar of the matrix metal, remelted and introduced into a spinning mold. Tubes can be produced with walls having differing amounts of reinforcing materials in the tube wall. Castings can be obtained having a uniform distribution of a reinforcement in a matrix metal.Type: GrantFiled: November 15, 1989Date of Patent: June 25, 1991Assignee: The United States of America as represented by the Secretary of the NavyInventors: Subhash D. Karmarkar, Amarnath P. Divecha
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Patent number: 4978054Abstract: A method of forming diffusion bonds between aluminum and aluminum alloy saces by coating the surfaces with molten AgNO.sub.3 and then decomposing the AgNO.sub.3 to form a thin uniform layer of silver on the surfaces before forming the diffusion bond. The AgNO.sub.3 coating and decomposition in treatment permanently breaks up the Al.sub.2 O.sub.3 coatings on the aluminum or aluminum alloy surfaces, making diffusion bonding possible.Type: GrantFiled: July 3, 1990Date of Patent: December 18, 1990Assignee: The United States of America as represented by the Secretary of the NavyInventors: William A. Ferrando, Amarnath P. Divecha, Subhash D. Karmarkar
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Patent number: 4958763Abstract: An aluminum or aluminum alloy surface is coated with molten AgNO.sub.3, the ilver nitrate is decomposed (at about 450.degree. C.-550.degree. C.) leaving a thin layer of silver metal, and then an inter-diffusion layer of silver and aluminum is formed (at about 570.degree. C.-660.degree. C.). The treated surface can be soldered by conventional means.Type: GrantFiled: August 29, 1989Date of Patent: September 25, 1990Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, William A. Ferrando, Philip W. Hesse, Subhash D. Karmarkar
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Patent number: 4578287Abstract: A method of treating a commercially available ion plated graphite/aluminum composite with suitable hydroscopic liquid selected from the group consisting of methylene chloride, toluene, xylene and where such liquid treatment results in capillary action in the graphite fibers and subsequently heat treating the graphite/aluminum composite in a hot processing step where magnesium powder is sublime at a temperature in the range of 350.degree.-450.degree. C. and where such sublime magnesium vapor uniformly coats graphite and aluminum in the composite material so as to obtain a graphite aluminum composite coated with magnesium.Type: GrantFiled: October 9, 1984Date of Patent: March 25, 1986Assignee: The United States of America as represented by the Secretary of the NavyInventors: Amarnath P. Divecha, Subhash D. Karmarkar, John V. Foltz