The behaviour of a cenosphere-resin composite under hydrostatic pressure

Abstract

Most deep submersible vehicles make use of a buoyancy material known as syntactic foam. This material is a composite made up of closely packed hollow glass microspheres embedded in a resin matrix. Typically the microspheres have diameters in the range 50–150μ. They are relatively expensive to manufacture and it is principally their cost which determines the cost of the syntactic foam. The ash from generating stations which burn pulverized coal contains a small proportion of hollow glassy microspheres, known as cenospheres, and these have about the right size distribution for use in syntactic foam. The ash disposal method used in certain British generating stations is such that the cenospheres can readily be collected as a useful lightweight product. Some preliminary pressurization experiments on a syntactic foam made with cenospheres have been carried out and these suggest that cenospheres will probably perform as well as the manufactured microspheres for at least some applications.