D Jianxin et al. Materials Science and Engineering A 444(2007)120-129 5e1115KvX1.5②K三9.0un Fig. 17. SEM micrographs of the entry bore surface of the worn CN-2 stress-free ceramic nozzle. (a) 05081115Kv 5ee1115K Fig. 18. SEM micrographs of the entry bore surface of the wom laminated ceramic nozzle: (a and b) GN-2 laminated nozzle, (c and d) GN-3 laminated nozzle. 4. Conclusions in nozzle entry region in fabricating process of the laminated ceramic nozzles, which may partially counteract the tensile Sic/W, Ti)C laminated ceramic nozzles were produced by stresses resulting from external loadings. Laminated struc hot pressing. The purpose is to reduce the tensile stress at the ture in ceramic nozzles is an effective way to improve the entrance area of the nozzle during dry sand blasting processes erosion wear resistance of the stress-free ceramic nozzles Particular attention was paid to the erosion wear behaviours of 2. The ceramic nozzle laminated both in entry and exit area this kind laminated ceramic nozzle. Results showed that (GN-3)exhibited higher erosion wear resistance over the one laminated only in entry area(GN-2) 1. The laminated ceramic nozzles(GN-2 and GN-3)have supe- Acknowledgements rior erosion wear resistance to that of the homologous stress ee ceramic nozzle(CN-2). The mechanism responsible was This work was supported by the"National Natural explained as the formation of compressive residual stresses F oundation of China (50475133)", "Natural Science Founda-128 D. Jianxin et al. / Materials Science and Engineering A 444 (2007) 120–129 Fig. 17. SEM micrographs of the entry bore surface of the worn CN-2 stress-free ceramic nozzle. Fig. 18. SEM micrographs of the entry bore surface of the worn laminated ceramic nozzle: (a and b) GN-2 laminated nozzle, (c and d) GN-3 laminated nozzle. 4. Conclusions SiC/(W,Ti)C laminated ceramic nozzles were produced by hot pressing. The purpose is to reduce the tensile stress at the entrance area of the nozzle during dry sand blasting processes. Particular attention was paid to the erosion wear behaviours of this kind laminated ceramic nozzle. Results showed that: 1. The laminated ceramic nozzles (GN-2 and GN-3) have supe￾rior erosion wear resistance to that of the homologous stress￾free ceramic nozzle (CN-2). The mechanism responsible was explained as the formation of compressive residual stresses in nozzle entry region in fabricating process of the laminated ceramic nozzles, which may partially counteract the tensile stresses resulting from external loadings. Laminated struc￾ture in ceramic nozzles is an effective way to improve the erosion wear resistance of the stress-free ceramic nozzles. 2. The ceramic nozzle laminated both in entry and exit area (GN-3) exhibited higher erosion wear resistance over the one laminated only in entry area (GN-2). Acknowledgements This work was supported by the “National Natural Science Foundation of China (50475133)”, “Natural Science Founda-