Hot Isostatic Pressing of Ceramic Powder Compacts.
Abstract
The effect of temperature, pressure and time on the rate of densification of submicron alumina powder during hot isostatic pressing has been determined using a dilatometer to continuously monitor volumetric changes. A Fortran computer program is used to make corrections for thermal expansion of the alumina and the stainless steel can, to determine the relative density of the alumina compact at any point, and to produce report ready graphs depicting the relationship between any two prescribed variables. Analysis of other errors associated with the use of the dilatometer shows that these are negligible compared with thermal expansion effects. The rate of densification is controlled by an interface reaction mechanism never previously observed in the densification of alumina. Mass transport is limited by the movement of grain boundary dislocations which act as sites for atoms to detach from grains. The actual rate limiting process is the diffusion of solute in the lattice since the motion of solute atoms can result in a large number of atoms being freed from a grain boundary dislocation. ONce separated from the dislocation the atoms quickly diffuse away.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 15, 1984
- Accession Number
- ADA144123
Entities
People
- J. K. Mccoy
- R. R. Wills
Organizations
- Battelle Memorial Institute