Accession Number : AD0632890

Title :   MACHINING HIGH PURITY ALUMINA.

Descriptive Note : Quarterly rept. no. 5, 28 Jun-28 Sep 65.

Corporate Author : LINDEN LABS INC STATE COLLEGE PA

Report Date : 28 OCT 1965

Pagination or Media Count : 24

Abstract : The rate of attack by 52% aqueous hydrofluoric acid on commercial grades of high purity alumina (96% and 94%) are discussed. The composition and the method of formation used appear to be parameters controlling the rate of attack. All 96% and 94% alumina engineering parts have been rendered friable by hydrofluoric acid treatment, machined and reconstituted. The 96% alumina parts have physical properties which suggest that they have been successfully reconstituted when fired to P.C.E. cone 33 (1745C) for four hours and were simultaneously transformed into parts of at least 99% alumina or better. Although the 94% alumina has been capable of being rendered friable and machinable it has not been successfully reconstituted. Reconstitution at P.C.E. cone 33 resulted in dense bodies which were warped and distorted. The warping of plates, cylinders and rods was not improved upon by reconstituting under the less severe conditions of P.C.E. cone 31 (1680C); in addition they had an open pore porosity of about 8% and, hence, would be unsatisfactory when measured against Mil I-10 A. (Author)

Descriptors :   (*REFRACTORY MATERIALS, MACHINING), (*MACHINING, *CERAMIC MATERIALS), (*ALUMINUM, OXIDES), INORGANIC ACIDS, FLUORIDES, SINTERING, PURIFICATION, DENSITY

Subject Categories : Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE