Sintering mechanisms of Yttria with different additives

The sintering behaviour of conventional yttria powder was investigated, with emphasis on the effect of sintering additives such as B2O3, YF3, Al2O3, ZrO2, and TiO2, etc. at sintering temperatures from 1000 degrees C to 1600 degrees C. Powder shrinkage behaviour was analysed using a dilatometer. The powder sintering mechanisms were identified at different temperatures using powder isothermal shrinkage curves. This analysis showed that the sintering additives B2O3 and YF3 could improve yttria sintering by changing the diffusion/sintering mechanisms at certain temperatures, while sintering additives TiO2, Al2O3 and ZrO2 appeared to retard the powder densification at temperatures around 1000 degrees C and are more suitable when used at temperatures in excess of 1300 degrees C. The powder with La2O3 added had the slowest densification rate throughout the test temperatures in this experiment and was also found to be more suitable when used at temperatures higher than 1550 degrees C. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.