Patents by Inventor John J. Croat

John J. Croat 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: 5352301
    Abstract: A method is provided for forming a high energy product, anisotropic, hot pressed iron-rare earth metal permanent magnet without the requirement for magnetic alignment during pressing or additional hot working steps. The method of this invention includes providing a quantity of anisotropic iron-rare earth metal particles and hot pressing the particles so as to form a substantially anisotropic permanent magnet. The pressed permanent magnet of this invention permits a greater variety of shapes as compared to conventional hot worked anisotropic permanent magnets. As a result, the magnetic properties and shape of the permanent magnet of this invention can be tailored to meet the particular needs of a given application.
    Type: Grant
    Filed: November 20, 1992
    Date of Patent: October 4, 1994
    Assignee: General Motors Corporation
    Inventors: Viswanathan Panchanathan, John J. Croat
  • Patent number: 5314548
    Abstract: A method is disclosed for producing a rapidly solidified, fine grained, magnetically anisotropic powder of the RE-Fe-B type. The rapidly solidified material is optimally quenched or slightly overquenched and is subjected to a hydrogen absorption-hydrogen desorption process that produces a fine grained material containing the essential magnetic phase RE.sub.2 TM.sub.14 B and an intergranular phase and is magnetically anisotropic.
    Type: Grant
    Filed: June 22, 1992
    Date of Patent: May 24, 1994
    Assignee: General Motors Corporation
    Inventors: Viswanathan Panchanathan, Gregory P. Meisner, John J. Croat
  • Patent number: 5174362
    Abstract: The hard magnetic properties, including intrinsic coercivity, remanence and energy product of rapidly quenched, rare earth-transition metal alloys has been substantially increased by the addition of suitable amounts of the element boron. The preferred rare earth constituent elements are neodymium and praseodymium, and the preferred transition metal element is iron.
    Type: Grant
    Filed: August 13, 1985
    Date of Patent: December 29, 1992
    Assignee: General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 5172751
    Abstract: Magnetically hard compositions having high values of coercivity, remanence and energy product contain rare earth elements, transition metal elements and boron in suitable proportions. The preferred rare earth elements are neodymium and praseodymium, and the preferred transition metal element is iron. The magnetic alloys have characteristic very finely crystalline microstructures.
    Type: Grant
    Filed: July 16, 1987
    Date of Patent: December 22, 1992
    Assignee: General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 5056585
    Abstract: Magnetically hard compositions having high values of coercivity, remanence and energy product contain rare earth elements, transition metal elements and boron in suitable proportions. The preferred rare earth elements are neodymium and praseodymium, and the preferred transition metal element is iron. The magnetic alloys have characteristic very finely crystalline microstructures.
    Type: Grant
    Filed: August 12, 1985
    Date of Patent: October 15, 1991
    Assignees: General Motors Corporation, General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 4902361
    Abstract: This invention relates to permanent bonded magnets of very finely crystalline, melt-spun, rare earth-iron alloys. The compacts are magnetically isotropic.
    Type: Grant
    Filed: February 10, 1986
    Date of Patent: February 20, 1990
    Assignee: General Motors Corporation
    Inventors: Robert W. Lee, John J. Croat
  • Patent number: 4881985
    Abstract: A method to produce rare earth (RE), iron, boron type anisotropic permanently magnetic material includes forming magnetically isotropic coarse powder particles of melt-spun alloy with a very fine grain RE.sub.2 FE.sub.14 B phase. The particles are mixed with inert particles of a size and of a weight percentage of the mixture to separate the powder particles for preventing hot work bonding therebetween. The mixture is hot pressed to cause the magnetically isotropic particles to be compressed in a direction parallel to the press direction so as to strain the particles to cause crystallites to be oriented along a crystallographically preferred magnetic axis resulting in particles of anisotropic permanently magnetic material.
    Type: Grant
    Filed: August 5, 1988
    Date of Patent: November 21, 1989
    Assignee: General Motors Corporation
    Inventors: Earl G. Brewer, Robert W. Lee, John J. Croat
  • Patent number: 4851058
    Abstract: The hard magnetic properties, including intrinsic coercivity, remanence and energy product of rapidly quenched, rare earth-transition metal alloys has been substantially increased by the addition of suitable amounts of the element boron. The preferred rare earth constituent elements are neodymium and praseodymium, and the preferred transition metal element is iron.
    Type: Grant
    Filed: September 3, 1982
    Date of Patent: July 25, 1989
    Assignee: General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 4802931
    Abstract: Magnetically hard compositions having high values of coercivity, remanence and energy product contain rare earth elements, transition metal elements and boron in suitable proportions. The preferred rare earth elements are neodymium and praseodymium, and the preferred transition metal element is iron. The magnetic alloys have characteristic very finely crystalline microstructures.
    Type: Grant
    Filed: October 26, 1983
    Date of Patent: February 7, 1989
    Assignee: General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 4756775
    Abstract: Magnetically hard compositions having high values of coercivity, remanence and energy product contain rare earth elements, transition metal elements and boron in suitable proportions. The preferred rare earth elements are neodymium and praseodymium, and the preferred transition metal element is iron. The magnetic alloys have characteristic very finely crystalline microstructures.
    Type: Grant
    Filed: October 26, 1983
    Date of Patent: July 12, 1988
    Assignee: General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 4496395
    Abstract: Ferromagnetic compositions having intrinsic magnetic coercivities at room temperature of at least 1,000 Oersteds are formed by the controlled quench of molten rare earth-transition metal alloys. Hard magnets may be inexpensively formed from the lower atomic weight lanthanide elements and iron.
    Type: Grant
    Filed: June 16, 1981
    Date of Patent: January 29, 1985
    Assignee: General Motors Corporation
    Inventor: John J. Croat
  • Patent number: 4347086
    Abstract: An amorphous rare-earth transition metal body is provided that has integral, predetermined regions of hard and soft magnetism. A method is provided for heating portions of an amorphous rare-earth transition metal alloy body, in situ, to transform predetermined portions from a state of low magnetic coercivity to a highly magnetically coercive state.
    Type: Grant
    Filed: April 7, 1980
    Date of Patent: August 31, 1982
    Assignee: General Motors Corporation
    Inventors: Andrew R. Chraplyvy, Jan F. Herbst, John J. Croat
  • Patent number: 4312684
    Abstract: A portion of a nonmagnetic body of manganese-aluminum based alloy is tempered in situ to a state of high magnetic coercivity. The magnetically coercive portion may be used, e.g., to store magnetically readable information or to provide a tailored permanent magnetic field for an electrical device.
    Type: Grant
    Filed: April 7, 1980
    Date of Patent: January 26, 1982
    Assignee: General Motors Corporation
    Inventors: Andrew R. Chraplyvy, John J. Croat, Jan F. Herbst
  • Patent number: 4076561
    Abstract: In a preferred embodiment thin layers of rare earth metal-cobalt powder comprising an outer layer of RCo.sub.5 and a discrete transitional layer of R.sub.2 Co.sub.17 are compressed against an adjacent thicker layer of iron powder to form a laminated green compact, with the rare earth-cobalt powdered material being magnetically aligned. The green laminate body is then sintered to densify the rare earth-cobalt material layer to a body wherein the pores are substantially noninterconnecting. The laminate structure is then magnetized. By this method a strong rare earth-cobalt (RCo.sub.5) permanent magnet body is produced in which the rare earth-cobalt layer may be very thin (of the order of 1 to 2 millimeters) but of relatively large surface area and supported by a strong iron layer so as to be durable in handling, manufacturing and use.It is possible to press an RCo.sub.5 layer directly onto a powdered iron layer when the oxygen content of the iron is suitably low. The method will also produce an R.sub.2 Co.sub.
    Type: Grant
    Filed: October 15, 1976
    Date of Patent: February 28, 1978
    Assignee: General Motors Corporation
    Inventors: Robert W. Lee, John J. Croat