Cenospheres are hollow ceramic microspheres with special characteristics that enable them to be used in a wide number of applications.
Cenosphere are light weight, inert hollow sphere of silica alumina filled with gas which naturally occurs in the combustion of coal. The sphere is nature's most efficient shape with the lowest surface area compares to volume. It is this shapes which cenosphere such a wide range of uses other than simply being used as lightweight fillers.
Cenosphere are having unique combination of low specific gravity, controlled size, and high compression, good thermal and accountable insulating property. Cenospheres are hard and rigid, light, waterproof, innoxious, and insulative. This makes them highly useful in a variety of products, notably fillers. Cenospheres are now used as fillers in cement to produce low density concrete. Recently, some manufacturers have begun filling metals and polymers with cenospheres to make lightweight composite materials with higher strength than other types of foam materials.
Cenosphere have a high melting point of 1200-1800 °C They are there fore excellent for use in high temperature insulating refracteries and fire resistance coating and panels.