Patents by Inventor Amarnath P. Divecha

Amarnath P. Divecha 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).

  • Patent number: 10173934
    Abstract: A method of producing a novel ceramic foam by treating a commercial ceramic foam with powdered glass in an aqueous/alcohol glass gel and with combined silicon carbide whiskers, where the impregnated foam is dried and sintered to form a porous article.
    Type: Grant
    Filed: April 25, 1984
    Date of Patent: January 8, 2019
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subash Karmarkar
  • Patent number: 7090893
    Abstract: A method of forming a rhenium layer on a substrate, comprising: applying a solid rhenium-containing compound to a substrate; reducing at a temperature above ambient temperature the rhenium-containing compound so that a rhenium layer is formed on the substrate; and optionally, repeating applying additional rhenium-containing compound on at least a section of the rhenium layer, and reducing at a temperature above ambient temperature the additional rhenium-containing compound so that a thicker layer of rhenium is formed.
    Type: Grant
    Filed: March 24, 2003
    Date of Patent: August 15, 2006
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Appajosula Srinivasa Rao, William A. Ferrando
  • Patent number: 6129135
    Abstract: 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: Grant
    Filed: June 29, 1999
    Date of Patent: October 10, 2000
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subhash D. Karmarkar, William A. May, James M. Kerr, William A. Ferrando, Scott M. Hoover
  • Patent number: 6129134
    Abstract: Reinforcing particles within a flux are dispersed through a metal matrix osited into a crucible purged of air by infeed of argon gas during heating of the matrix to a melted state for completing particle dispersion by agitation before remelting thereof after solidification. The remelted matrix with the particles fully dispersed therein is then allowed to undergo sedimentation increasing particle concentration along a flat surface portion of the final product having increased wear resistance thereat.
    Type: Grant
    Filed: March 11, 1999
    Date of Patent: October 10, 2000
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Amarnath P. Divecha
  • Patent number: 6116328
    Abstract: 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: Grant
    Filed: July 29, 1999
    Date of Patent: September 12, 2000
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Subhash D. Karmarkar, Amarnath P. Divecha, William J. Bruchey, Gerald Bulmash, James M. Kerr, William A. Ferrando
  • Patent number: 6082436
    Abstract: 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: Grant
    Filed: January 28, 1999
    Date of Patent: July 4, 2000
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subhash D. Karmarkar, Philip Hesse, William J. Bruchey
  • Patent number: 5858460
    Abstract: 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: Grant
    Filed: July 1, 1991
    Date of Patent: January 12, 1999
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Amarnath P. Divecha, James Kerr, Subhash D. Karmarkar
  • Patent number: 5509459
    Abstract: 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: Grant
    Filed: September 28, 1994
    Date of Patent: April 23, 1996
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subhash D. Karmarkar, Scott M. Hoover, James M. Kerr, William A. Ferrando
  • Patent number: 5362580
    Abstract: A process for producing a lightweight electrode grid by exposing a compred, heated mat of dense graphite fibers to Ni(CO).sub.4 gas wherein the Ni(CO).sub.4 decomposes upon contact with the graphite fibers depositing a nickel metal coating on the graphite fibers which strongly bonds the fibers together to form a compressed mat or grid of nickel metal coated fibers.
    Type: Grant
    Filed: July 7, 1993
    Date of Patent: November 8, 1994
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Amarnath P. Divecha
  • Patent number: 5337803
    Abstract: 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: Grant
    Filed: May 25, 1993
    Date of Patent: August 16, 1994
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subhash D. Karmarkar, William A. Ferrando, Scott M. Hoover
  • Patent number: 5261151
    Abstract: A Nb-Ti or Nb-Zr low temperature superconducting (LTS) wire is coat with ten AgN0.sub.3 which is then decomposed to form a uniform silver metal (Ag) coating on the LTS wire. A uniform coating of molten Al or Al alloy is formed on the Ag coated LTS wire and then solidified. A bundle of the coated LTS wires is inserted into an Al or Al alloy tube and cold worked to form a multifilamentary LTS cable comprising the Ag coated LTS wires each surrounded by an Al or Al alloy matrix.
    Type: Grant
    Filed: July 17, 1992
    Date of Patent: November 16, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Amarnath P. Divecha, James Kerr
  • Patent number: 5253797
    Abstract: 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: Grant
    Filed: July 21, 1992
    Date of Patent: October 19, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Subhash D. Karmarkar, Scott M. Hoover, Amarnath P. Divecha
  • Patent number: 5254529
    Abstract: A high temperature superconducting wire or yarn has a first layer thereon yttria, a third layer of barium cuprate, and a second layer of a superconducting YBa.sub.2 Cu.sub.3 O.sub.7-x formed at the interface between the first and third layers. The wire can be yttrium and the yarn can be alumina.
    Type: Grant
    Filed: October 31, 1991
    Date of Patent: October 19, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, James M. Kerr
  • Patent number: 5214234
    Abstract: 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: Grant
    Filed: July 17, 1992
    Date of Patent: May 25, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subhash D. Karmarkar, Scott M. Hoover, William A. Ferrando
  • Patent number: 5197993
    Abstract: A process for producing a lightweight electrode grid by exposing a heated t of dense graphite fibers to Ni(CO).sub.4 gas wherein the Ni(CO).sub.4 decomposes upon contact with the graphite fibers depositing nickel metal coating on the graphic fibers. The nickel coated graphite fibers are then sintered to form the grid. Nickel or cadmium electrodes are made by attaching a current collector to the grid and impregnating the grid with the appropriate nickel or cadmium active material.
    Type: Grant
    Filed: July 11, 1991
    Date of Patent: March 30, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Amarnath P. Divecha
  • Patent number: 5193605
    Abstract: 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: Grant
    Filed: November 4, 1991
    Date of Patent: March 16, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, Subhash D. Karmarkar, William A. Ferrando, Scott M. Hoover, James M. Kerr
  • Patent number: 5120575
    Abstract: A reaction vessel comprising (1) a porous ceramic structure having intercecting, open pores and (2) silver metal coating the inner ceramic surfaces of the reaction vessel and filling the interconnecting, open pores to form a strong bond between the porous ceramic structure and the silver coating.The reaction vessel can be produced by(1) coating the inner surface and infiltrating the continuous, open pores of an unglazed porous ceramic structure (or vessel) with molten AgNO.sub.3 ;(2) decomposing the AgNO.sub.3 to silver metal; and then(3) repeating steps (1) and (2) until all the pores are filled with silver metal.
    Type: Grant
    Filed: May 10, 1991
    Date of Patent: June 9, 1992
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Amarnath P. Divecha, James Kerr
  • Patent number: 5100049
    Abstract: A method of bonding two carbon/carbon composite pieces or a carbon/carbon mposite piece and a graphite/aluminum metal matrix composite piece together by(1) forming a uniform coating of molten AgNO.sub.3 on the surfaces to be bonded at a temperature above the melting point of AgNO.sub.3 but below the decomposition temperature of AgNO.sub.3 ;(2) placing the molten AgNO.sub.3 coated surfaces to be bonded into contact with each other;(3) decomposing the molten AgNO.sub.3 to form a silver metal layer bonding the pieces together.If a graphite/aluminum metal matrix composite piece is being bonded, a silver diffusion step may be added at the end of the process to strengthen the silver bond to the metal cladding or metal matrix of the metal matrix composite piece.
    Type: Grant
    Filed: July 1, 1991
    Date of Patent: March 31, 1992
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, William A. Ferrando, Philip W. Hesse, Subhash D. Karmarkan
  • Patent number: 5051307
    Abstract: 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: Grant
    Filed: July 3, 1990
    Date of Patent: September 24, 1991
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Amarnath P. Divecha, William A. Ferrando, Philip W. Hesse, Subhash D. Karmarkar
  • Patent number: H1718
    Abstract: A process for producing a superconductor wire by:A. coating the inner surface of a steel tube with a thin layer of silver metal;B. packing the tube with high temperature superconductor ceramic (HTSC) powder;C. sealing the tube;D. cold working the tube to reduce its diameter;E. etching or dissolving away the steel tube to leave a superconductor wire comprising the silver metal coating that was on the inner surface of the steel tube as a thin silver metal sheath which encapsulates the HTSC powder.The superconductor wire can be further treated by sintering or oxygenating the HTSC powder.
    Type: Grant
    Filed: July 20, 1992
    Date of Patent: April 7, 1998
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: William A. Ferrando, Amarnath P. Divecha, James M. Kerr