Preparation of Transparent Yttrium Oxide Ceramics by HIP Sintering.

Abstract

Transparent yttrium oxide (Y₂O₃) ceramics were prepared by combined sintering technique of pressureless sintering and hot isostatic pressing (HIP). After compacting at 140 MPa by using cold isostatic pressing (CIP), the compacts of Y₂O₃ were sintered at 1400 to 1700 °C for 90 to 240 min in air. Following the pressureless sintering, HIP was carried out at 1850 °C for 120 min under 180 MPa. The optimum condition was HIP at 1850 °C for 120 min under 180 MPa after pressureless sintering at 1600 °C for 240 min.Specimen of 3.0 mm thickness had in-line transmittance of 70 % in visible region and 80 % in infrared region. Neither pore nor precipitates of the second phase were observed at the grain boundary, and then the extensive grain growth was observed.