Back to results
US 5,139,978 AGranted
Impregnation method for transformation of transition alumina to a alpha alumina
AssigneeMinnesota Mining and Manufacturing Company
InventorThomas E. Wood
Life of this patent
Estimating the term…
Abstract
The method of the present invention is useful in preparing an improved alpha alumina-based ceramic. The improvement consists of the addition of a precursor of an alpha phase nucleating to transition alumina. The method is particularly useful in preparing alpha alumina-based abrasive grain.
Claims39
A method of making an alpha alumina-based ceramic, having a seeded microstructure comprising alpha alumina domains nucleated with an alpha chromic oxide nucleating agent, said method comprising the steps of:
- a) preparing a liquid admixture which comprises a sufficient amount of a precursor of alpha chromic oxide that when converted to alpha chromic oxide nucleates the transformation of transition alumina to alpha alumina, wherein said alpha alumina has a seeded microstructure;
- b) impregnating said admixture of step (a) into a transition alumina-based body;
- c) drying said impregnated transition alumina body;
- d) calcining said dried impregnated transition alumina body at a temperature an in an atmosphere sufficient to substantially remove volatile materials and convert said precursor to its nucleating phase;
- and
- e) sintering said calcined-impregnated transition alumina body at a temperature and in an atmosphere sufficient to provide an alpha alumina-based ceramic having a seeded microstructure comprising alpha alumina domains nucleated with alpha chromic oxide.
3 more elements
Dependencies are inferred from the claim text.