Temperature-dependent surface topography analysis of Illinois class F fly ash using ESEM and AFM

The evolution of particle surface morphology of Illinois Class F fly ash with calcination temperature was monitored using atomic force microscopy (AFM) and environmental scanning electron microscopy (ESEM). Significant new information on particle chemical composition and morphology was obtained using ESEM and AFM. Particularly, AFM provides detailed information on the roughness of the particle, which increased with the calcination temperature. Noticeable changes in fly ash surface morphology as a function of temperature has been noticed using ESEM. Thermal treatment of fly ash particles produces a very rough surface, often resulting from the formation of surface deposits, as well as pitting of the particle surface. Energy depressive X-ray analysis provided detailed information on the chemical nature of fly ash particles. No significant changes in elemental concentration were noticed, although oxygen concentration reduced upon calcination. A correlation of the surface microscopical quantitative information with the elemental analysis is presented, which can be very helpful for engineering applications where fly ash particles are used as metal filler.