Physical, Thermal, and Chemical Properties of Fly Ash Cenospheres Obtained for Different Sources

Cenospheres are hollow particles in fly-ash, a by-product of coal burning, and are widely used as reinforcement for developing low density composites called syntactic foams. This study investigates the physical, chemical, and thermal properties of cenospheres obtained from 3 different sources, CS1, CS2, and CS3, for the development of syntactic foams. Description of floatation method to separate broken particles is given, and it was seen that up to 11 % of the particles were damaged. Post heat treatment samples show development of SiO2 phase in the cenosphere, which is not present in the as received product. CS3 had the highest quantity of Si element, compared to the other two, showing the difference in the source quality. The particle size distribution for CS2 is very narrow while for the others is much broader. All censopheres have porous walls but the morphology of CS2 is the most uniform and smooth. For the application of metallic layer and subsequent consolidation via spark plasma sintering, CS2 was deemed the most physically, thermally, and chemically suitable.