Alpha phase seeding of transition alumina using chromium oxide-based nucleating agents

A method of making an alpha alumina-based ceramic, said method comprising the steps of:

• a) preparing an aqueous mixture comprising:
• i) an alpha alumina precursor;
• and
• ii) a sufficient amount to nucleate during the following process steps said alpha alumina precursor to alpha alumina having a seeded microstructure of at least one chromium compound selected from the group consisting of an alpha chromic oxide precursor, alpha chromic oxide, and mixtures thereof;
• b) immobilizing said aqueous mixture;
• c) drying said immobilized aqueous mixture to produce a dry body;
• d) calcining said body at a temperature and in an atmosphere sufficient to provide substantially all the chromium derived from said chromium compound within said body in an oxidation state of not greater than +3;
• and
• e) sintering said calcined body at a temperature and in an atmosphere sufficient to provide alpha alumina-based ceramic having a seeded microstructure.