ATOMIC-FORCE MICROSCOPY DETERMINATION OF THE TOPOGRAPHY OF FLY-ASH PARTICLES

We report on the first AFM images to our knowledge of the surface topography of fly-ash glassy spheres. Optically, two types of spheres are observed: large ones (more than 100 mu m diameter) appear dark, small ones (up to 10 mu m diameter) appear clear. Both were observed by AFM. The light spheres do not appear to present much structure on their surface. In contrast, the dark spheres present numerous craters typically of 300 nm diameter and 10 nm depth. Small particles, the largest of about 110 nm and the smallest 13 nm in size, were also observed on top of the largest glassy spheres.