Inhibition of grain growth in liquid-phase sintered SiC ceramics by AlN additive and spark plasma sintering

SiC ceramics were prepared from nanosized beta-SiC powder with different compositions of AlN and Y(2)O(3) sintering additives by spark plasma sintering (SPS) at 1900 degrees C for 600 s in N(2). The relative density of the sintered SiC specimens increased with increasing amount of AlN, reaching a relative density higher than 99%, while at the same time grain size decreased significantly. The smallest average grain size of 150 nm was observed for SiC sample sintered with 10 vol% of additives consisting of 90 mol% AlN and 10 mol% Y(2)O(3). Fully dense nanostructured SiC ceramics with inhibited grain growth were obtained by the AlN additive and SPS technique. The flexural strength of the SiC body containing 70 mol% AlN and 30 mol% Y(2)O(3) additives reached the maximum value of 1000 MPa. The SiC bodies prepared with AlN and Y(2)O(3) additives had the fracture toughness of around 2.5 MPam(1/2). (c) 2010 Elsevier Ltd. All rights reserved.