J. Deng et al. /Ceramics International 36(2010)299-306 Fig 9. Wall surface profiles of the worn CwS nozzles after 120 h operation: (a) N5 stress-free nozzle, ( b)INI layered nozzle, and (c) LN3 layered nozzle. (d) Fig. 10. SEM micrographs of the wall surface of the CwS nozzles after 120 h operation:(a)wall surface of N5 stress-free nozzle, (b)enlarged SEM micrograph corresponding to(a),(c)wall surface of LNI layered nozzle, and(d)enlarged SEM micrograph corresponding to(c) impact the wall surface of the nozzle at low angles. As resistance of the layered nozzles may be explained by their high erodent particles in CWS were much softer than the ceran surface hardness(see Table 3) nozzles, sliding abrasive particles in the CwS can act as a The damage of ceramics subjected to temperature gradient polishing medium on the nozzle wall surface. Therefore, the environments is another major limiting factor in relation to eroded wall surface of the nozzle is very smooth(see Fig. 10), service requirements and lifetime performance. Repetitive and the hardness of the CWs nozzles plays an important role thermal shock also results in thermal fatigue hich has a with respect to their erosive wear. The ceramic nozzles with significant effect on the life of the Cws nozzles. For high hardness had smaller erosion rates. The high erosion determination of the thermal stresses inside the nozzle whenimpact the wall surface of the nozzle at low angles. As the erodent particles in CWS were much softer than the ceramic nozzles, sliding abrasive particles in the CWS can act as a polishing medium on the nozzle wall surface. Therefore, the eroded wall surface of the nozzle is very smooth (see Fig. 10), and the hardness of the CWS nozzles plays an important role with respect to their erosive wear. The ceramic nozzles with high hardness had smaller erosion rates. The high erosion resistance of the layered nozzles may be explained by their high surface hardness (see Table 3). The damage of ceramics subjected to temperature gradient environments is another major limiting factor in relation to service requirements and lifetime performance. Repetitive thermal shock also results in thermal fatigue, which has a significant effect on the life of the CWS nozzles. For determination of the thermal stresses inside the nozzle when Fig. 10. SEM micrographs of the wall surface of the CWS nozzles after 120 h operation: (a) wall surface of N5 stress-free nozzle, (b) enlarged SEM micrograph corresponding to (a), (c) wall surface of LN1 layered nozzle, and (d) enlarged SEM micrograph corresponding to (c). Fig. 9. Wall surface profiles of the worn CWS nozzles after 120 h operation: (a) N5 stress-free nozzle, (b) LN1 layered nozzle, and (c) LN3 layered nozzle. 304 J. Deng et al. / Ceramics International 36 (2010) 299–306