Eu stabilized α-sialon ceramics derived from SHS-synthesized powders

The characteristics of Eu-stabilized α-sialon ceramics derived from self-propagating high-temperature synthesis (SHS) Eu α-sialon powders without and with the addition of Y2O3 are investigated. The results showed that the amount of α-sialon phase formed in sintered Eu α-sialon composition was much less than that in SHS-ed powder when the composition was hot-pressed at 1800 °C for 1 h, while the transformation of α-sialon to β-sialon phase did occur at the same time, which could be attributed to the metastability of SHS-ed powder because of the high heating and cooling rate during the SHS process and the reduction of Eu3+ to Eu2+ under the reduction conditions during hot pressing. By addition of Y2O3 into SHS-ed Eu α-sialon powder, thus to form (Y,Eu) α-sialon phase in the sintered sample, the stability of α-sialon phase was improved, as the ratio of α-sialon to α-sialon was increased from 70 wt.% in SHS-ed powder to 83 wt.% in the sintered product by 50 mol% of Y2O3 added into SHS-ed powder.