Wear behavior of ceramic nozzles in coal water slurry burning

In this paper, Al2O3/(W,Ti)C ceramic composite and WC/Co cemented carbide were prepared for the use of nozzle materials in coal water slurry (CWS) burning. The wear behavior of nozzles made from these materials was compared by determining the cumulative volume loss and the erosion rates. Results showed that the hardness of the nozzles plays an important role with respect to its erosion wear in CWS burning processing. The Al2O3/(W,Ti)C nozzles possessing high hardness exhibited lower erosion rates, while the WC/Co cemented carbide nozzles with a low hardness showed higher erosion rates under the same test conditions. Examination of eroded bore surface of the nozzles showed that wear of the WC/Co cemented carbide nozzle occurred by a preferential removal of the metal binder followed by pluck out of the exposed WC grains, while the primary wear mechanisms of Al2O3/(W,Ti)C ceramic nozzle exhibited polishing action in the hole and thermal shock damage with chipping at the bore exit. (C) 2003 Elsevier Ltd and Techna Group S.r.l. All rights reserved.