Effect of Y2O3 addition on the properties of reaction-bonded porous SiC ceramics

Abstract Porous SiC ceramics were fabricated without and with Y 2 O 3 addition from SiC, Al 2 O 3 and graphite in air by the in situ reaction bonding process. This process is based on the oxidation of SiC and the mullitization between Al 2 O 3 and oxidation-derived SiO 2 . SiC particles are bonded by the mullite (3Al 2 O 3 ·2SiO 2 ) and SiO 2 . The pores are produced by both stacking SiC particles and burning out graphite. Comparison of phase composition, microstructure, flexural strength, open porosity and pore size distribution of reaction-bonded porous SiC ceramics without and with Y 2 O 3 addition was conducted. Moreover, the effect of Y 2 O 3 content was investigated. Due to the enhancement of neck formation (bonding part between SiC particles) by the addition of Y 2 O 3 , a high strength of 27.5 MPa was achieved at an open porosity of 44.4%.