CONSTANT HEATING RATE ANALYSIS OF SIMULTANEOUS SINTERING MECHANISMS IN ALUMINA

Constant heating rate sintering experiments were conducted on a submicron alumina powder during the initial stage. Shrinkage was measured by precision dilatometry and surface area reduction was monitored with gas adsorption measurements. Furthermore, grain size and pore size results were collected using X-ray line broadening and mercury porosimetry. Analysis of the shrinkage and surface area reduction data showed excellent correlation with a computer simulation based on simultaneous surface diffusion and grain boundary diffusion mechanisms. A comparison of the simulated and the experimental sintering paths on a plot of surface area reduction versus shrinkage indicated the combination of mechanisms and activations energies which best describe this sintering behaviour. From this analysis the estimated activation energies for grain boundary and surface diffusion are 440 and 508 kJ mol-1, respectively.