ABSTRACT
This chapter discusses the physical properties of different types of condensed silica fume, with special attention to their variability with time from a given source. Condensed silica fume, being only a by-product, varies in its degree of purity and consistency because these are not major concerns for silicon or ferrosilicon production. Grain size distribution of condensed silica fume particles can be determined using an electron microscope. Condensed silica fume from Si manufacture is expected to be the finest because the production of silicon metal is associated with the highest energy input and temperature. Specific surface area of condensed silica fume is most commonly measured by nitrogen adsorption method. Condensed silica fume particles observed through an electron microscope appear in the form of a cluster of particles. X-ray diffractograms of samples of different types of condensed silica fume show them to be vitreous.
