Preparation and Characterization of Pressureless Sintered Alumina/5 vol % SiC Micro-Nanocomposites

Alumina/5 vol % SiC micro-nanocomposites were produced by slip-casting and pressureless sintering. The dispersion of alumina and SiC particles in water using an electrosteric dispersant was studied for different solid contents. Although the rheological and granulometry measurements showed that the optimum amount of Darvan C for well-dispersing 50 wt % dry matter slurries was 0.20 vol %, this content was increased to 1.00 vol % in order to avoid the demixing of SiC nanoparticles during shaping. Well densified (> 99%) alumina-SiC pressureless sintered materials were obtained at 1800 & DEG;C-2 h in which SiC nanoparticles occupied inter/intragranular positions. The creep behaviour of these materials was examined at 1200 & DEG;C under stresses ranging from 70 to 140 MPa. A good creep resistance in alumina-SiC materials was obtained demonstrating that the use of less expensive conventional sintering methods is possible and highlighting the importance of the dispersion step.