ULTRAPURE ALUMINA CERAMICS FORMED BY COPRECIPITATION

• US 3,637,406 A
• Filed: 12/23/1970
• Issued: 01/25/1972
• Est. Priority Date: 12/23/1970
• Status: Expired due to Term

• Current Assignee: Great American Industrial Group Incorporated
• Original Assignee: Joseph T. Bailey
• Inventors: Bailey, Joseph T.
• Primary Examiner(s): Poer, James E.
• Assistant Examiner(s): Satterfield, W. R.
• Application Number:
  US05/101,150
• Time in Patent Office: 398 Days
• Field of Search: 106/39R,65,62 23/141,143 264/65,56,60 252/452
• US Class Current: 501/153
• CPC Class Codes: C04B 35/10 based on aluminium oxide

Abstract

Alumina ceramics of homogeneous composition and fine-grained structure are produced using alpha-alumina obtained by calcination of aluminum oxide hydroxide including any desired adjuvants.

Claims

2. The process according to claim 1 wherein calcining temperature range is 1,200* to 1350* C.

3. The process according to claim 1 wherein about one-fourth to 1 percent of substantially ash-free grinding aid is employed in breaking down agglomerates and the amount of substantially ash-free temporary organic binder is 1-5 percent.

4. The process according to claim 1 wherein the temporary organic binder is microcrystalline wax.

5. The process according to claim 1 wherein the temporary organic binder is polyvinylalcohol.

6. The process according to claim 1 wherein the temporary organic binder is polyvinylpyrrolidone.

7. The process according to claim 1 wherein the temporary organic binder is water-dispersed acrylate or methacrylate.

8. The product of the process of claim 1 consisting essentially of alpha-alumina of high purity and magnesium oxide together with organic grinding aid and temporary binder.