Improvement of Mechanical Properties and Corrosion Resistance of Porous β‐SiAlON Ceramics by Low Y ₂ O ₃ Additions

Abstract

Addition of Y 2 O 3 as a sintering additive to porous β‐SiAlON (Si 6− z Al z O z N 8− z , z = 0.5) ceramics has been investigated for improved mechanical properties. Porous SiAlON ceramics with 0.05–0.15 wt% (500–1500 wppm) Y 2 O 3 were fabricated by pressureless sintering at temperatures of 1700°, 1800°, and 1850°C. The densification, microstructure, and mechanical properties were compared with those of Y 2 O 3 ‐free ceramics of the same chemical composition. Although this level of Y 2 O 3 addition did not change the phase formation and grain size, the grain bonding appeared to be promoted, and the densification to be enhanced. There was a significant increase in the flexural strength of the SiAlON ceramics relative to the Y 2 O 3 ‐free counterpart. After exposure in 1 M hydrochloric acid solution at 70°C for 120 h, no remarkable weight loss and degradation of the mechanical properties (flexural and compression strength) was observed, which was attributed to the limited grain boundary phase, and with the minor Y 2 O 3 addition the supposed formation of Y‐α‐SiAlON.