β‐Sialon Ceramics Prepared at 1700°C by Hot Isostatic Pressing

Dense, single‐phase β‐sialon ceramics were sintered at 1700°C and 200 MPa using the glass‐encapsulated hot isostatic pressing technique. The materials were very hard, 1500 to 1700 kg / mm 2 (98 N load), but were fairly brittle, with an indention fracture toughness of about 3 MPa · m 1/2 . The addition of 1 wt% Y 2 O 3 before sintering had a positive effect on the toughness, especially at the low x compositions of Si 3‐x Al x O x N 4‐x , where K IC ∼4 MPa · m 1/2 .