Initial Sintering of α-Cr2O3 |
| |
Authors: | WILLIAM C HAGEL P J JORGENSEN D S TOMALIN |
| |
Affiliation: | Metallurgy and Ceramics Department, Research Laboratory, General Electric Company, Schenectady, New York 12301 |
| |
Abstract: | Since the difference between oxygen-ion and cation diffusion coefficients is greater for α-Cr2O3 than for α-Fe2O3 or α-Al2O3, a study of initial-sintering kinetics was undertaken to show unequivocally which species is rate controlling. Fine powders of α-Cr2O3, obtained by thermal decomposition of reagent-grade (NH4)2Cr2O7, were lightly compacted and their isothermal rates of shrinkage were determined between 1050° and 1300°C. Resultant data follow volume-diffusion sintering models, and calculated diffusion coefficients agree with, those measured for oxygen ions in α-Cr2O3. There is little evidence that oxygen diffusion along grain boundaries becomes so enhanced that chromium ions are left in control of the process. |
| |
Keywords: | |
|
|