Patents by Inventor Dwarika P. Agarwal

Dwarika P. Agarwal 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: 8419867
    Abstract: Rose-color and yellow-color gold alloys are formed from a gold-base alloy containing silver and copper. Mining these elements is usually highly detrimental to the environmental. Environmentally friendly alloys are obtained through the use of recycled elements and elements recovered from mines utilizing specific guidelines. Jewelry manufactured from these environmentally friendly alloys may be more receptive to a consumer, resulting in a competitive advantage.
    Type: Grant
    Filed: August 15, 2008
    Date of Patent: April 16, 2013
    Assignee: Hallmark Sweet, Inc.
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum, Richard V. Carrano
  • Publication number: 20090191089
    Abstract: Rose-color and yellow-color gold alloys are formed from a gold-base alloy containing silver and copper. Mining these elements is usually highly detrimental to the environmental. Environmentally friendly alloys are obtained through the use of recycled elements and elements recovered from mines utilizing specific guidelines. Jewelry manufactured from these environmentally friendly alloys may be more receptive to a consumer, resulting in a competitive advantage.
    Type: Application
    Filed: August 15, 2008
    Publication date: July 30, 2009
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum, Richard V. Carrano
  • Patent number: 7413705
    Abstract: Improved 14-karat rose-colored gold alloy compositions include: about 58.5% gold; about 9.0-12.0% silver; about 0.0-0.2% zinc; about 0.3-0.4% cobalt; about 0.0-0.02% iridium; and about 29.0-33.0% copper. Improved 18-karat rose-colored gold alloy compositions include: about 75.2% gold; about 7.0% silver; about 0.0-0.2% zinc; about 0.3-0.4% cobalt; about 0.0-0.02% iridium; and about 17.0-17.5% copper. The hardness of these compositions are capable of being selectively changed between their respective annealed-hardness and age-hardness values. The color of these compositions is between about 5-7 CieLab a* color units and between about 17-21 CieLab b* color units.
    Type: Grant
    Filed: May 9, 2005
    Date of Patent: August 19, 2008
    Assignee: Leach & Garner Company
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum
  • Patent number: 7198683
    Abstract: A sterling silver alloy composition of exceptional and reversible hardness and enhanced tarnish resistance, consists essentially of the following parts by weight: at least about 92.5% silver; about 4.4% to about 5.25% copper; about 0% to about 1.0% zinc; about 0.85% tin; about 0.05% to about 0.3% lithium; about 0.05% to about 0.5% silicon; about 0% to about 1.2% germanium; and about 0% to about 0.02% boron.
    Type: Grant
    Filed: August 26, 2004
    Date of Patent: April 3, 2007
    Assignee: Leach & Garner Company
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum
  • Patent number: 7135078
    Abstract: A nickel-free white gold alloy composition having selectively reversible hardness characteristics between its annealed- and aged-hardness values, consists essentially of: about 55–60% gold; about 6.0–10.0% palladium; about 5.0–12.0% copper; about 0.1–2.0% zinc; and about 20–30% silver. A 14-karat nickel-free white gold alloy composition, consists essentially of: about 58.5% gold; about 25.0–27.15% silver; about 6.0% palladium; about 5.0–12.0% copper; about 0–2.0% zinc; about 0–0.2% cobalt; about 0–0.005% iridium; and about 0–0.01% lithium.
    Type: Grant
    Filed: December 5, 2005
    Date of Patent: November 14, 2006
    Assignee: Leach & Garner Company
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum
  • Patent number: 6676776
    Abstract: A 14-karat gold alloy composition having a desirable yellow color and with reversible hardness contains about 58.65 weight percent gold, about 11.5-25.0 weight percent silver, about 11.85-23.35 weight percent copper, and about 2-7 weight percent zinc. The color of the composition has a value of between about −3.0 to about 0.5 CieLab a* color units, and has a value of between about +20.0 to about 22.0 CieLab b* color units. The alloy has a hardness ratio between about 0.4-2.0, and color ratio of less than about 1.0.
    Type: Grant
    Filed: August 20, 2002
    Date of Patent: January 13, 2004
    Assignee: Leach & Garner Company
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum
  • Patent number: 6406568
    Abstract: An improved 18-karat green gold alloy composition comprises about 75.0% gold; about 6.0-7.0% silver; about 9.0-11.7% copper; and about 6.5-9.0% zinc. The improved alloys are capable of being age-hardened to a hardness of about 240 VHN by being heated to about 550° F. for about one hour, and thereafter being permitted to cool in air. The hard-nesses of the alloys are reversible between their aged-hardness and annealed-hardness values. The color of said composition is between about −1.5 to about −3.0 CieLab a* color units, and between about 19 to about 26 CieLab b* color units.
    Type: Grant
    Filed: August 22, 2001
    Date of Patent: June 18, 2002
    Assignee: Leach & Garner Company
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum
  • Patent number: 5919320
    Abstract: A hardenable white gold alloy consists essentially of about 55-60 % gold, about 12-20% silver, about 8-15% copper, about 8-18% palladium, about 0.0-1.0% tin, zinc indium or cobalt, and, optionally, about 0.005-0.02% iridium and/or ruthenium, and also about 0.01-0.03 weight percent lithium. The alloy is nickel-free, but has a pleasing white color similar to that of nickel-containing white gold alloys. The alloy has a fine grain structure, a lower hardness in its annealed condition, but is capable of being hardened to an exceptional hardness value. The hardening procedure is reversible.
    Type: Grant
    Filed: November 17, 1997
    Date of Patent: July 6, 1999
    Assignee: Leach & Garner Company
    Inventors: Dwarika P. Agarwal, Grigory Raykhtsaum
  • Patent number: 5598722
    Abstract: An improved bangle closing mechanism (26) is adapted to releasably join two tubular arcuate bangle halves (11, 12). The improved closing mechanism has a keeper bar (28) provided with a proximal portion (29) adapted to be operatively engaged with the first bangle half (11), an intermediate portion (30) extending between the bangle halves and penetrating a narrowed opening (23) in the second bangle half (12), and an enlarged ball-like head portion (31) operatively arranged within the second bangle half. The projected diameter (d.sub.1) of the head portion is greater than the projected diameter (d.sub.2) of the narrowed opening. The head portion prevents the keeper bar from being withdrawn from the second bangle half, and facilitates sliding movement within the second bangle half as to the bangle halves are moved relatively toward or away from one another.
    Type: Grant
    Filed: April 3, 1995
    Date of Patent: February 4, 1997
    Assignee: Leach & Garner Company
    Inventors: Edwin F. Leach, II, Marinko Markic, Ronald E. Precourt, Jr., Michael A. Gayton, Dwarika P. Agarwal
  • Patent number: 5180551
    Abstract: A unique hardenable gold based alloy, especially a 14 karat gold alloy containing gold, silver, copper, zinc, cobalt and an alternative alloy additionally containing iridium. The alloy has a fine grained structure, a lower hardness in the soft condition, a nice yellow color and a capability to be hardened to an exceptional hardness value. The alloy contains approximately 58.3% gold (Au), between about 10% to about 14% silver (Ag), between about 2.5% to about 3.0% zinc (Zn), between about 0.2% to about 1.0% cobalt (Co) and the balance of the alloy being copper (Cu) with the special provision that the ratio of the weight percent amounts of copper to, the sum of the silver and two (2) times the zinc amount, [Cu/(Ag+2Zn)], has a value of between about 1.3 to about 2.5. The copper to silver weight percent ratio [Cu/Ag] of between about 2.0 to about 3.8, in combination with the ratio of copper to, silver+2.times.
    Type: Grant
    Filed: October 30, 1991
    Date of Patent: January 19, 1993
    Assignee: Leach & Garner Co.
    Inventor: Dwarika P. Agarwal
  • Patent number: 5139883
    Abstract: Gold, copper, silver, palladium or aluminum and their alloys, but preferably gold or gold alloy, which may be in the form of a wire, has deposited thereon or contained within the wire, a material such as metals or metal alloys which diffuse into the gold or into the other listed metals. With the passage of time and exposure to temperature the deposited metal or metal alloy continues to diffuse into the gold forming intermetallics with the gold and thereby causing the resistivity of the gold to increase and causing the gold to become progressively more brittle until such time as the gold wire ruptures at a stress point. At a given temperature, the elapsed time until rupture takes place depends upon the metal or metal alloys deposited on or contained within the gold. Lead, indium, gallium, tin, bismuth and aluminum and the alloys of these metals diffuse into and form intermetallics with the gold.
    Type: Grant
    Filed: May 9, 1989
    Date of Patent: August 18, 1992
    Inventors: Grigory Raykhtsaum, Dwarika P. Agarwal, James R. Valentine, David J. Kinneberg
  • Patent number: 5130689
    Abstract: Gold, copper, silver, palladium or aluminum and their alloys, but preferably gold or gold alloy, which may be in the form a wire, has deposited thereon or contained within the wire, a material such as metals or metal alloys which diffuse into the gold or into the other listed metals. With the passage of time and exposure to temperature the deposited metal or metal alloy continues to diffuse into the gold forming intermetallics with the gold and thereby causing the resistivity of the gold to increase and causing the gold to become progressively more brittle until such time as the gold wire ruptures at a stress point. At a given temperature the elapsed time until rupture takes place depends upon the metal or metal alloys deposited on or contained within the gold. Lead, indium, gallium, tin, bismuth and aluminum and the alloys of these metals diffuse into and form intermetallics with the gold.
    Type: Grant
    Filed: January 16, 1991
    Date of Patent: July 14, 1992
    Assignee: Leach & Garner Co.
    Inventors: Grigory Raykhtsaum, Dwarika P. Agarwal
  • Patent number: 5000779
    Abstract: The subject of this invention is the development of new alloys along with new processing approaches for the utilization of the alloys. A particular class of alloys comprises at least one noble metal selected from the group comprising gold, palladium, silver and copper and an amount of between about 0.20 weight percent and about 0.80 weight percent of at least one metalloid selected from the group of metalloids consisting of boron, phosphorous, silicon and lithium. Rapid solidification technology in powder fabrication and the addition of metalloids have been combined to produce a new class of palladium based alloys. The metalloid additions greatly increase the hardness, enhance the fine grain structure and aid sintering densification. Net-shape forming is a benefit derived from the characteristics of the new alloys.
    Type: Grant
    Filed: May 18, 1988
    Date of Patent: March 19, 1991
    Assignee: Leach & Garner
    Inventors: Randall M. German, Laura L. Bourguignon, Dwarika P. Agarwal, Shaji Faroog
  • Patent number: 4869757
    Abstract: A unique hardenable silver alloy is provided which is solution annealed and preferably age-hardened to yield a silver alloy of exceptional and reversible hardness. The alloys utilize intermetallic systems comprising; silver, copper, combined with lithium alone or tin alone in varying percent amounts, or silver, copper, lithium and either tin or antimony, or silver, copper, lithium, tin and antimony, or silver, copper, lithium, tin and bismuth, or silver, copper, lithium, tin, bismuth and antimony.
    Type: Grant
    Filed: April 13, 1987
    Date of Patent: September 26, 1989
    Assignee: Leach & Garner Company
    Inventors: Thomas W. Eagar, Dwarika P. Agarwal, Laura L. Bourguignon, Rosaire Marcotte
  • Patent number: 4810308
    Abstract: A unique hardenable silver alloy is provided which is solution annealed and preferably age-hardened to yield a silver alloy of exceptional and reversible hardness. The alloys utilize intermetallic systems comprising silver, copper, combined with lithium alone or tin alone in varying percent amounts, or silver, copper, lithium and either tin or antimony, or silver, copper, lithium and either aluminum or indium or zinc, or silver, copper, antiomony and either aluminum or indium or zinc, or silver, copper, lithium, tin and antimony, or silver, copper, lithium, tin and bismuth, or silver, copper, lithium, tin, bismuth and antimony.
    Type: Grant
    Filed: January 19, 1988
    Date of Patent: March 7, 1989
    Assignee: Leach & Garner Company
    Inventors: Thomas W. Eagar, Dwarika P. Agarwal, Laura L. Bourguignon, Rosaire Marcotte
  • Patent number: 4399096
    Abstract: A brazing alloy composition for joining chromium containing base metal alloys containing, by weight, palladium about 39%-60%, nickel about 20%-47.5%, and at least one element selected from the group consisting of silver 0-35%, tin 0-32%, indium 0-32% and gallium 0-11%; and optionally containing one or more elements selected from the group consisting of gold 0-10%, germanium 0-4.4%, silicon 0-2.9% and about 0.025% of a known deoxidizer such as lithium. The alloy exhibits good wetting and flowing characteristics and has excellent strength and corrosion resistance at elevated temperatures. The brazing alloy is particularly useful for joining chromium containing baese metal alloys of the type which are used in the porcelain-fused-to-metal technic in dental prosthetics.
    Type: Grant
    Filed: June 7, 1982
    Date of Patent: August 16, 1983
    Assignee: Williams Gold Refining Company Incorporated
    Inventors: Dwarika P. Agarwal, Clyde E. Ingersoll
  • Patent number: 4249943
    Abstract: An alloy composition for dental use containing, by weight, aluminum 0-3.0%, cobalt 0-20.0%, chromium 10.0-20.0%, manganese 0-1.5%, molybdenum 6.0-18.0%, nickel 58.5-77.0% and silicon 0-2.0%. The alloy retains the corrosion resistance properties found in nickel-chromium base alloys while having reduced yield strength typical of gold alloys thereby resulting in greater ease of grinding, polishing and manipulation. The alloy finds use as a porcelain substrate alloy and also as a crown and bridge or partial denture alloy.
    Type: Grant
    Filed: October 11, 1978
    Date of Patent: February 10, 1981
    Assignee: Williams Gold Refining Company Incorporated
    Inventors: M. Hamdi A. Mohammed, Dwarika P. Agarwal, Clyde E. Ingersoll