Patents by Inventor Ratnesh K. Dwivedi

Ratnesh K. Dwivedi 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: 5188164
    Abstract: The present invention relates to a novel process for forming macrocomposite bodies and the novel bodies formed thereby. Particularly, a suitable matrix metal, typically in a molten state, is in contact with a suitable mass of filler material or preform located adjacent to, or in contact with, at least one second material in the presence of a suitable reactive atmosphere in an impermeable container, at least at some point during the process, which permits a reaction to occur between the reactive atmosphere and the molten matrix metal and/or mass of filler material or preform and/or impermeable container, thereby causing molten matrix metal to infiltrate the mass of filler material or preform due to, at least in part, the creation of a self-generated vacuum. Such self-generated vacuum infiltration occurs without the application of any external pressure or vacuum.
    Type: Grant
    Filed: July 31, 1990
    Date of Patent: February 23, 1993
    Assignee: Lanxide Technology Company, LP
    Inventors: Robert C. Kantner, Ratnesh K. Dwivedi
  • Patent number: 5163498
    Abstract: The present invention relates to a novel process for forming net or near net-shape metal matrix composite bodies. Particularly, a molten matrix metal is in contact with a filler material or a preform in the presence of a reactive atmosphere, at least at some point during the process, which permits molten matrix metal to react, at least partially or substantially completely, with the reactive atmosphere, thereby causing molten matrix metal to infiltrate the filler material or preform due to the creation of a self-generated vacuum. Forming a glassy seal on the reaction system, the self-generated vacuum infiltration occurs without the application of any external pressure or vacuum. The molten matrix metal infiltrates the filler material up to at least a portion of a provided barrier means.
    Type: Grant
    Filed: November 7, 1989
    Date of Patent: November 17, 1992
    Assignee: Lanxide Technology Company, LP
    Inventors: Robert C. Kantner, Ratnesh K. Dwivedi
  • Patent number: 5141902
    Abstract: A self-supporting ceramic composite body produced by a method which comprises preparing a polycrystalline material as the oxidation reaction product of a parent metal with a vapor-phase oxidant, comminuting the resulting material to a particulate, forming a permeable mass of said particulate as filler, and infiltrating said particulate with an oxidation reaction product of a parent metal with a vapor-phase oxidant, thereby forming said ceramic composite body.
    Type: Grant
    Filed: September 27, 1991
    Date of Patent: August 25, 1992
    Assignee: Lanxide Technology Company, LP
    Inventors: Marc S. Newkirk, Danny R. White, Ratnesh K. Dwivedi
  • Patent number: 5139977
    Abstract: There is disclosed a method for making a self-supporting ceramic composite article having a porous core bearing a dense surface layer formed integrally with said core. A preform comprises a filler material and parent metal distributed therethrough, wherein the volume percent of parent metal is sufficient to form a volume of oxidation reaction product exceeding the total volume available within said preform. The parent metal is melted and reacted with an oxidant to form an oxidation reaction product filling the spatial volume and leaving voids. The reaction is continued to further transport molten parent metal through the oxidation reaction product to at least one surface of the preform to form oxidation reaction product on said surface substantially free of voids thereby forming a relatively dense surface layer.
    Type: Grant
    Filed: May 13, 1991
    Date of Patent: August 18, 1992
    Assignee: Lanxide Technology Company, LP
    Inventor: Ratnesh K. Dwivedi
  • Patent number: 5120580
    Abstract: There is disclosed methods for producing self-supporting ceramic matrix and ceramic matrix composite bodies by batch, semi-continuous, and continuous processes utilzing the directed oxidation of a molten parent metal with an oxidant to form an oxidation reaction product which may embed filler material.
    Type: Grant
    Filed: May 14, 1990
    Date of Patent: June 9, 1992
    Assignee: Lanxide Technology Company, LP
    Inventors: Harold D. Lesher, Ratnesh K. Dwivedi, Perry B. Goldberg
  • Patent number: 5084425
    Abstract: This invention relates to a self-supporting ceramic strucutre comprising an oxidation reaction product of a parent metal and a vapor-phase oxidant characterized by an altered microstructure attributable to the addition of one or more process modifiers relative to substantially the same oxidation reaction product produced without a process modifier.
    Type: Grant
    Filed: March 11, 1991
    Date of Patent: January 28, 1992
    Assignee: Lanxide Technology Company, LP
    Inventors: Robert C. Kantner, Michael K. Aghajanian, Stanislav Antolin, Alan S. Nagelberg, Ratnesh K. Dwivedi
  • Patent number: 5082700
    Abstract: A method is provided for producing a self-supporting ceramic composite body having a plurality of spaced apart wall members, each wall member having a bounded cross-section for defining substantially continuous, fluid passageways. The wall members generally inversely replicate in opposed directions the geometry of a positive pattern. Each of the wall members, which are axially aligned, comprises a ceramic matrix having a filler embedded therein, and is obtained by the oxidation reaction of a parent metal to form a polycrystalline material which comprises the oxidation reaction product of the parent metal with an oxidant and, optionally, one or more metals, e.g. nonoxidized constituents of the parent metal.
    Type: Grant
    Filed: October 30, 1989
    Date of Patent: January 21, 1992
    Assignee: Lanxide Technology Company, LP
    Inventor: Ratnesh K. Dwivedi
  • Patent number: 5063185
    Abstract: A method of producing self-supporting ceramic or ceramic composite structures comprising (i) a polycrystalline oxidation reaction product formed upon oxidation of a body of molten parent metal with an oxidant, and (ii) interconnected porosity at least partially accessible from one or more surfaces of the ceramic or ceramic composite body. A second polycrystalline ceramic material is incorporated into the porosity of the ceramic or ceramic composite body to modify or contribute to its properties.
    Type: Grant
    Filed: July 2, 1990
    Date of Patent: November 5, 1991
    Assignee: Lanxide Technology Company, LP
    Inventors: Ratnesh K. Dwivedi, Christopher R. Kennedy
  • Patent number: 5053367
    Abstract: A self-supporting ceramic composite body produced by a method body which comprises preparing a polycrystalline material as the oxidation reaction product of a parent metal with a vapor-phase oxidant, comminuting the resulting material to a particulate, forming a permeable mass of said particulate as filler, and infiltrating said particulate with an oxidation reaction product of a parent metal with a vapor-phase oxidant, thereby forming said ceramic composite body.
    Type: Grant
    Filed: June 22, 1990
    Date of Patent: October 1, 1991
    Assignee: Lanxide Technology Company, LP
    Inventors: Marc S. Newkirk, Danny R. White, Ratnesh K. Dwivedi
  • Patent number: 5019541
    Abstract: This invention relates to a method for producing a self-supporting ceramic structure comprising an oxidation reaction product of a parent metal and a vapor-phase oxidant characterized by an altered microstructure attributable to the addition of one or more process modifiers relative to substantially the same oxidation reaction product produced without a process modifier.
    Type: Grant
    Filed: July 2, 1990
    Date of Patent: May 28, 1991
    Assignee: Lanxide Technology Company, LP
    Inventors: Robert C. Kantner, Michael K. Aghajanian, Stanislav Antolin, Alan S. Nagelberg, Ratnesh K. Dwivedi
  • Patent number: 5015610
    Abstract: There is disclosed a method for making a self-supporting ceramic composite article having a porous core bearing a dense surface layer formed integrally with said core. A preform comprises a filler material and parent metal distributed therethrough, wherein the volume percent of parent metal is sufficient to form a volume of oxidation reaction product exceeding the total volume available within said preform. The parent metal is molted and reacted with an oxidant to form an oxidation reaction product filling the spatial volume and leaving voids. The reaction is continued to further transport molten parent metal through the oxidation reaction product to at least one surface of the preform to form oxidation reaction product on said surface substantially free of voids thereby forming a relatively dense surface layer.
    Type: Grant
    Filed: September 28, 1989
    Date of Patent: May 14, 1991
    Assignee: Lanxide Technology Company, LP
    Inventor: Ratnesh K. Dwivedi
  • Patent number: 5005631
    Abstract: The present invention relates to a novel method for forming a metal matrix composite body, and products produced thereby. Particularly, a permeable mass of filler material is formed into a preform, the preform having at least a portion thereof which contains a cavity. An infiltration enhancer and/or an infiltration enhancer precursor and/or an infiltrating atmosphere are also in communication with the preform, at least at some point during the process, which permits molten matrix metal to spontaneously infiltrate the preform when the preform is placed into molten matrix metal. An infiltrating atmosphere is provided in communication with the cavity in the preform for at least a portion of the process, and molten matrix metal is contacted with an exterior portion of the preform, such that molten matrix metal will spontaneously infiltrate the preform from an exterior surface thereof toward the cavity.
    Type: Grant
    Filed: November 10, 1988
    Date of Patent: April 9, 1991
    Assignee: Lanxide Technology Company, LP
    Inventor: Ratnesh K. Dwivedi
  • Patent number: 5000246
    Abstract: The present invention relates to a novel method for forming metal matrix composite bodies. Particularly, a permeable mass of filler material is formed into a preform. The preform material can then be floated onto the surface of or into a matrix metal alloy, whereupon the matrix metal alloy spontaneously infiltrates the preform. After substantial complete infiltration of the preform, the preform begins to at least partially sink into the matrix metal alloy supply. The matrix metal which has infiltrated the preform is then allowed to cool, thus forming a metal matrix composite body.
    Type: Grant
    Filed: November 10, 1988
    Date of Patent: March 19, 1991
    Assignee: Lanxide Technology Company, LP
    Inventors: Ratnesh K. Dwivedi, John T. Burke
  • Patent number: 4998578
    Abstract: An aluminum metal matrix composite comprises an aluminum metal matrix embedding a second filler, such as a ceramic second filler, and is formed by contacting, for example, a molten aluminum metal with a permeable mass of second filler within a ceramic impervious mold formed by growing a polycrystalline oxidation reaction product into a first filler. By hermetically sealing the second filler within the mold with a body of molten aluminum metal, the latter spontaneously infiltrates the mass of second filler at moderate temperatures, e.g. about 900.degree. C., without need of any other infiltration expedients. The molten mass containing the infiltrated ceramic filler is solidified to provide the metal matrix composite which may be recovered from the mold.
    Type: Grant
    Filed: July 17, 1989
    Date of Patent: March 12, 1991
    Assignee: Lanxide Technology Company, LP
    Inventors: Ratnesh K. Dwivedi, Virgil Irick, Jr.
  • Patent number: 4996176
    Abstract: A method for producing a self-supporting ceramic composite structure which includes a ceramic matrix embedding a filler, includes oxidizing a parent metal to form a polycrystalline material comprising the oxidation reaction product of the parent metal with an oxidant and, optionally, one or more metallic constituents, and the filler embedded by the matrix. The method includes heating a first source of molten parent metal and a source of molten parent metal and contacting the first source of molten parent metal with a permeable bedding of filler. The first source of molten parent metal is reacted with the oxidant to form the oxidation reaction product and is replenished from the reservoir as the reacting continues for a time sufficient to grow the oxidation reaction product to a desired extent and thereby embed at least a portion of the bedding of filler within the oxidation reaction product to form the ceramic composite structure.
    Type: Grant
    Filed: September 28, 1989
    Date of Patent: February 26, 1991
    Assignee: Lanxide Technology Company, LP
    Inventors: Marc S. Newkirk, H. Daniel Lesher, Ratnesh K. Dwivedi, Robert C. Kantner
  • Patent number: 4956319
    Abstract: This invention relates to a new ceramic-metal composite body and a method for producing the same. Particularly, a compliant layer composition is utilized for preventing the rupture of a ceramic article and/or the yielding or failure of a metal during the pouring, solidification and cooling of a molten metal which has been cast around the ceramic. A slurry composition for the compliant layer includes plaster of paris, a liquid vehicle and a filler material. The slurry composition is coated on the ceramic article and thereafter is heat-treated to form a compliant layer. Ceramic-metal composite bodies comprising low strength hollow articles and high expansion coefficient metals may be manufactured according to the method of this invention.
    Type: Grant
    Filed: January 18, 1989
    Date of Patent: September 11, 1990
    Assignee: Lanxide Technology Company, LP
    Inventors: Ratnesh K. Dwivedi, Virgil Irick, Jr.
  • Patent number: 4956137
    Abstract: There is disclosed a method for making a self-supporting ceramic composite article having a porous core bearing a dense surface layer formed integrally with said core. A preform comprises a filler material and parent metal distributed therethrough, wherein the volume percent of parent metal is sufficient to form a volume of oxidation reaction product exceeding the total volume available within said preform. The parent metal is melted and reacted with an oxidant to form an oxidation reaction product filling the spatial volume and leaving voids. The reaction is continued to further transport molten parent metal through the oxidation reaction product to at least one surface of the preform to form oxidation reaction product on said surface substantially free of voids thereby forming a relatively dense surface layer.
    Type: Grant
    Filed: September 16, 1986
    Date of Patent: September 11, 1990
    Assignee: Lanxide Technology Company, LP
    Inventor: Ratnesh K. Dwivedi
  • Patent number: 4900699
    Abstract: A method for producing a self-supporting ceramic composite structure, which includes a ceramic matrix embedding a filler, includes oxidizing a parent metal to form a polycrystalline material comprising the oxidation reaction product of the parent metal with an oxidant and, optionally, one or more metallic constituents, and the filler embedded by the matrix. The method includes heating a first source of molten parent metal and a reservoir source of molten parent metal and contacting the first source of molten parent metal with a permeable bedding of filler. The first source of molten parent metal is reacted with the oxidant to form the oxidation reaction product and is replenished from the reservoir as the reacting continues for a time sufficient to grow the oxidation reaction product to a desired extent and thereby embed at least a portion of the bedding of filler within the oxidation reaction product to form the ceramic composite structure.
    Type: Grant
    Filed: September 16, 1986
    Date of Patent: February 13, 1990
    Assignee: Lanxide Technology Company, LP
    Inventors: Marc S. Newkirk, H. Daniel Lesher, Ratnesh K. Dwivedi, Robert C. Kantner
  • Patent number: 4886766
    Abstract: A method is provided for producing a self-supporting ceramic composite body having a plurality of spaced apart wall members, each wall member having a bounded cross-section for defining substantially continuous, fluid passageways. The wall members generally inversely replicate in opposed directions the geometry of a positive pattern. Each of the wall members, which are axially aligned, comprises a ceramic matrix having a filler embedded therein, and is obtained by the oxdiation reaction of a parent metal to form a polycrystalline material which comprises the oxidation reaction product of the parent metal with an oxidant and, optionally, one or more metals, e.g. nonoxidized constituents of the parent metal.
    Type: Grant
    Filed: August 10, 1987
    Date of Patent: December 12, 1989
    Assignee: Lanxide Technology Company, LP
    Inventor: Ratnesh K. Dwivedi
  • Patent number: 4871008
    Abstract: An aluminum metal matrix composite comprises an aluminum metal matrix embedding a second filter, such as a ceramic second filler, and is formed by contacting, for example, a molten aluminum metal with a permeable mass of second filler within a ceramic impervious mold formed by growing a polycrystalline oxidation reaction product into a first filler. By hermetically sealing the second filler within the mold with a body of molten aluminum metal, the latter spontaneously infiltrates the mass of second filler at moderate temperatures, e.g. about 900.degree. C., without need of any other infiltration expedients. The molten mass containing the infiltrated ceramic filler is solidified to provide the metal matrix composite which may be recovered from the mold.
    Type: Grant
    Filed: January 11, 1988
    Date of Patent: October 3, 1989
    Assignee: Lanxide Technology Company, LP
    Inventors: Ratnesh K. Dwivedi, Virgil Irick, Jr.