U.S. patents available from 1976 to present.
U.S. patent applications available from 2005 to present.

Process for producing tungsten heavy alloy billets

Patent 4744944 Issued on May 17, 1988. Estimated Expiration Date: Icon_subject August 5, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Patent References

3888636

Ductile tungsten-nickel alloy and method for making same
Patent #: 3979209
Issued on: 09/07/1976
Inventor: Snyder, Jr.

Process for fabricating articles of tungsten-nickel-iron alloy
Patent #: 3979234
Issued on: 09/07/1976
Inventor: Northcutt, Jr. ,   et al.

Tungsten-nickel-cobalt alloy and method of producing same
Patent #: 4012230
Issued on: 03/15/1977
Inventor: Dickinson ,   et al.

Ductile tungsten-nickel-alloy and method for manufacturing same
Patent #: 4090875
Issued on: 05/23/1978
Inventor: Ludwig

Process for producing molybdenum and tungsten alloys containing metal carbides
Patent #: 4670216
Issued on: 06/02/1987
Inventor: Patrician ,   et al.

Sintering process Patent #: 4698096
Issued on: 10/06/1987
Inventor: Schmidberger ,   et al.

Inventors

Assignee

Application

No. 07/081779 filed on 08/05/1987

US Classes:

419/23, Powder shape or size characteristics419/29, Subsequent heat treatment (e.g., annealing, etc.)419/46, Alloying occurs during sintering419/47, Liquid phase sintering419/53, Plural heating steps including sintering419/54, Different temperatures419/58, Hydrogen or hydrogen plus nitrogen (Nitrogen per se in 57)75/248Base metal confined to Tungsten(W)

Examiners

Primary: Lechert, Stephen J. Jr.

Attorney, Agent or Firm

International Classes

B22F 3/12 (20060101)
C22C 1/04 (20060101)

Abstract

A process is disclosed for producing tungsten heavy alloy billets. The process involves forming a uniform blend of elemental powders to form a tungsten alloy having a tungsten content of equal to or less than about 91% by weight and wherein the particle size of the tungsten is no less than about 2 micrometers in diameter. This blend is uniformly packed into a container having thermal expansion similar to that of the powder. The blend is then sintered in a hydrogen atmosphere at a temperature sufficient to impart strength to the powder and to reduce oxides and remove volatile impurities from the powder without significant densification in the powder. The powder is then solid state sintered in a reducing atmosphere at a sufficient temperature to densify the powder to at least about 90% of the theoretical density but at a temperature below the liquid phase sintering temperature of the powder, to form the billet. If the tungsten content of the alloy is greater than about 88% by weight, the solid state sintered powder can then be liquid state sintered by slowly raising the temperature from the solid state sintering temperature to the liquid phase sintering temperature and holding at this temperature for a sufficient time to accomplish the liquid sintering and achieve a density of greater than about 99% of the theoretical density in the billet.

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