Sintering behaviour of nanocrystalline Y₂O₃

Sintering behaviour of nanocrystalline yttria with a grain size of 25 nm was investigated. Pellets of 10 mm diameter were pressed uniaxially at 60 MPa and subsequently cold isostatically pressed at 200 MPa. Sintering studies were performed at temperatures between 1200°C-1300°C for 10-960 min to obtain densities from 60-100% theoretical density. The grain size was measured by the linear intercept method as a function of density. Sintering paths of nanocrystalline yttria were obtained and are discussed in comparison to microcrystalline yttria. Rapid coarsening at low temperatures and densities occurs in nanocrystalline yttria. Also differential sintering is observed. At later stages coarsening and densification occur simultaneously.