Patents by Inventor Ivanka S. Grozdanova

Ivanka S. Grozdanova 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: 4893793
    Abstract: The thermostable amorphous ferromagnetic powder containing iron, cobalt, or nickel, also comprises xylene from 0.2 to 25% by volume of the powder particles, up to 20% chrome and boron by weight, and lithium or magnesium in amounts from 0.1 to 2.0% by weight. The powder is resistant to oxidizing up to temperatures of 250.degree. C. and has a specific surface up to 160m.sup.2 /g.The method for its manufacture comprises reduction of a solution containing salts of iron, cobalt, chrome, a complexing agent, and metal salts or polyvalent alcohols by means of a reductant sodium borohydride in the presence of sodium hydroxide. The solution is protected by an organic hydrophobic substance--xylene during a period from 5 seconds to 10 minutes in the presence of a magnetic field.The device for manufacture of the thermostable amorphous ferromagnetic powder comprises a vertical reactor with a stirrer and electromagnet generating a magnetic field.
    Type: Grant
    Filed: March 23, 1988
    Date of Patent: January 16, 1990
    Assignee: VMEI LENIN
    Inventors: Dimiter T. Butchkov, Yovka D. Dragieva, Zvetan K. Nikolov, Georgi G. Georgiev, Mina S. Slavtcheva-Staikova, Ivanka S. Grozdanova
  • Patent number: 4822409
    Abstract: The thermostable amorphous ferromagnetic powder containing iron, cobalt, or nickel, also comprises xylene for 0.2 to 25% by volume of the powder particles, up to 20% chrome and boron by weight, and lithium or magnesium in amounts from 0.1 to 2.0% by weight. The powder is resistant to oxidizing up to temperatures of 250.degree. C. and has a specific surface up to 160m.sup.2 /g.The method for its manufacture comprises reduction of a solution containing salts of iron, cobalt, chrome, a complexing agent, and metal salts or polyvalent alcohols by means of a reductant sodium borohydride in the presence of sodium hydroxide. The solution is protected by an organic hydrophobic substance - xylene during a period from 5 seconds to 10 minutes in the presence of a magnetic field.The device for manufacture of the thermostable amorphous ferromagnetic powder comprises a vertical reactor with a stirrer and electromagnet generating a magnetic field.
    Type: Grant
    Filed: March 23, 1988
    Date of Patent: April 18, 1989
    Assignee: VMEI Lenin, Quartal Darvenitza
    Inventors: Dimiter T. Butchkov, Yovka D. Dragieva, Zvetan K. Nikolov, Georgi G. Georgiev, Mina S. Slavtcheva-Staikova, Ivanka S. Grozdanova