The interactions between coal-ash and a variety of refractory materials with a potential as refractory quarls have been studied in a 0.5 MW combustion test facility. A Clay-bonded SiC refractory has been found to react least with coal-ash, but not as a result of its lower surface temperatures. It is suggested that oxidation of the SiC leads to CO2 evolution from the surface of the refractory, hindering coal-ash penetration into the refractory. A technique for modifying the surface of rammable refractory materials, to reduce the adhesion strength of coal-ash deposits, is proposed. Initial results indicate that the technique can be successful and could easily be applied in a utility boiler. (C) 2003 Elsevier Ltd. All rights reserved.