Preparation and Characterization of Sintered Coal Fly-Ash Bulk Material by Spark Plasma Sintering (SPS)

Coal fly ash-based bulk materials were prepared by spark plasma sintering (SPS). As-received and fired powders were used as starting materials, where firing was treated at 1200°C for 24 hours in the air. Sintering temperature changes depending on starting materials; that is, 730°C for as-received and 830°C for fired powders, respectively. The obtained samples were highly-densed materials, where density was 2.8×103kg/m3 for sintered at 1070°C using fired powders. X-ray diffraction patterns of sintered materials indicate that mullite phase is predominant in all samples. SiO2, Al2O3, and Fe2O3 phases were also confirmed from result of electron probe microanalysis (EPMA). Vickers hardness of sintered fly ash was 726∼821, indicating that these materials have possibilities for application as structural materials.