Sintering mechanisms in aluminum nitride with Y or Ca-containing additive
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AlN with 4 wt.% Y2O3 or CaO were prepared by sintering in dilatometer and conventional furnace up to 1850 °C. The aim of this work was to compare the sintering behavior and mechanisms related with the densification of AlN with Y or Ca-containing additives. The sample with Y2O3 approached 33% of total densification by solid-state sintering process preceding the liquid phase formation, which was near 1700 °C. After the formation of liquid an overheating of only 50 °C was needed for this sample to achieve full density. The sample with CaO formed liquid-phase near 1400 °C, but required a higher overheating (>300 °C) in order to achieve full density. The densification of the sample with CaO was retarded by: (i) high viscosity of the liquid-phase formed below 1600 °C; (ii) formation of large pores; and (iii) gas entrapped inside the pores.
KeywordsY2O3 Calcium Aluminate Shrinkage Rate Linear Shrinkage Full Density
The authors acknowledge the Brazilian agencies FAPESP and CNPq for the financial support of the present research.
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