Accession Number : AD0710608

Title :   INTERMEDIATE STAGE DENSIFICATION IN VACUUM HOT PRESSING OF ALUMINA.

Descriptive Note : Research rept. Nov 68-Jun 69,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Rossi,Ronald C. ; Buch,James D.

Report Date : 31 JUL 1970

Pagination or Media Count : 32

Abstract : An analysis was made of the densification kinetics preceding the final stage densification of alumina hot pressed in vacuum between 1150 and 1350C and between 2000 and 6000 psi. The analysis suggests a diffusional creep mechanism, possibly consistent with a Narbarro-Herring vacancy model. The measured activation energy, 116 kcal/mole, agrees with the activation energy for the final stage of densification and for the self-diffusion of aluminum ions in alumina. It is conjectured that the pore structure (i.e., open or closed) determines the stage of densification and further that pore structure has a profound effect on the apparent diffusion coefficients. (Author)

Descriptors :   (*HOT PRESSING, *ALUMINA), DENSITY, HEAT OF ACTIVATION, REACTION KINETICS, CREEP

Subject Categories : Ceramics, Refractories and Glass
      Mfg & Industrial Eng & Control of Product Sys

Distribution Statement : APPROVED FOR PUBLIC RELEASE