HEAT ACCUMULATING BLOCKS BASED ON THE PYROPHYLLITE AND THERMALLY EXPANDED GRAPHITE

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-56-8 / ISSN 1314-2704, June 28 - July 6, 2016, Book1 Vol. 2, 1089-1096 pp

ABSTRACT
Electrically conductive composites are widely employed as electrical heating elements, heat accumulation blocks and others. By the mechanical mixing the thermally expanded graphite (TEG), pyrophyllite and kaolin (as binder) the electroconductive composite materials were obtained. These materials have heat accumulation properties and can be used in the autonomous heating system as a heat accumulation blocks. The prospects of using pyrophyllite as a matrix and the possibility of partial replacement of kaolin were shown. A comparative analysis of main functional properties of composite was made. Based on pyrophyllite and kaolin a manufacturing technology of heat accumulation blocks was obtained. Analysis of obtained microphotographs of the material shows that the structure of the material is highly porous and layered. Layered structure provides high sensitivity of resistive properties of the strain in the direction perpendicular to the layers. Microphotographs showed that TEG particles in the forming process create flat agglomerates that are evenly distributed on the volume of ceramic matrix. The influence of ratio of pyrophyllite and kaolin on the porosity and electrical resistivity of a new composite material was investigated. It was shown that replacing kaolin by pyrophyllite makes possible to increase significantly the electrical conductivity of composites.

Keywords: thermally expanded graphite (TEG), pyrophyllite, kaolin, heat accumulation blocks