Patents by Inventor Hongtu Chang

Hongtu Chang 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).

  • Method of producing high surface area, low metal impurity
    Patent number: 5234491
    Abstract: A process for producing a high purity tantalum powder wherein a small quantity of an active ingredient, having a higher thermodynamic potential and chemical activity than the metal surfaces of the reactor vessel, is added to the reactor before the reactor is heated to reaction temperatures.
    Type: Grant
    Filed: February 7, 1992
    Date of Patent: August 10, 1993
    Assignee: Cabot Corporation
    Inventor: Hongtu Chang