Properties and applications of a pitch carbon microsphere composite

Some properties and applications of a pitch carbon microsphere composite are described. The small hollow microspheres are made from the pitch which is usually a wasted by-product of petroleum refining. In contrast to high density composites or syntactic foams in which microspheres are inclusions within a continuous matrix, this composite is an aggregate of microspheres bonded together by a small amount of thermosetting polymer which does not form a continuous matrix. The result is a composite with low density and thermal expansion, modest strength and rigidity, and high porosity and carbon content. Mechanical, thermal, and sorption properties have been measured. Applications of the composite include honeycomb filler for high temperature or ionizing radiation fields and a wicking absorber for solar-powered stills.