Performances of Multiphase Ceramics of SiC and Praseodymium Aluminates

Abstract

Multiphase ceramics of SiC based composites were prepared by hot pressed (HP) and pressureless sintering with Al2O3 and Pr2O3 as sintering additives. The compositions were designed according to the two binary compounds of PrAlO3(PrAP) and PrAl11O18[β(Pr)] formed in Al2O3–Pr2O3 system. And the performances of the multiphase ceramics with different content of the second phases were investigated. The results showed that the weight loss, linear shrinkage and relative density of the samples in the group 1/B (SiC–PrAl11O18) containing more Al2O3 were higher than those of the samples in the group 1/1(SiC–PrAlO3) by pressureless sintering, and its supreme relative density was 91.5%. By hot pressed sintering, the relative density of the densest sample in group 1/1 and group 1/B reached 94.8 and 95%, respectively. In group 1/1, sample with 10wt% of additives possessed the greatest hardness of 21.1 GPa, and the maximal flexure strength of 494.9 MPa was achieved when additives content increased to 15 wt%. The sample containing 10wt% of additives in group 1/B had the best fracture toughness of 7.4 MPa m1/2.