Samples of refractory materials with adhering coal-ash deposits were collected from the burner quarl regions of boilers at two power stations. The degree of slag/refractory interaction was evaluated from polished cross-sections. Silicon carbide refractory materials showed better resistance than alummosilicate materials to slag chemical attack and penetration. Quarl design had also played a significant role with less attack to quarls with reduced surface areas filled with rammable refractories of reduced thickness. Since a rammable refractory is cured in situ in a boiler, the refractory closest to the water tubes will not fully cure leading to a reduction in thermal conductivity. (C) 2003 Elsevier Ltd. All rights reserved.