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Zhao evaluate during C211 2006 Elsevier Ltd. All rights reserved. abrasive particles and carrier gas coming out from a nozzle impinges on the target surface and erodes it. The fine par- mass flow rate and impact angle 57, the erodent abrasive properties 810, the nozzle material and its geometry section in sand blasting (see Fig. 1), the nozzle entry region suers form severe abrasive impact, which may cause large tance 1922. Residual stresses arise from a mismatch between the coecients of thermal expansion (CTE), sin- tering rates and elastic constants of the constituent phases and neighbouring layers, and the residual stress field depends on the geometry of the layered structure and on the thickness ratio among layers 2326. Toschi 22 * Corresponding author. Tel.: +86 531 88392047. E-mail address: (D. Jianxin). International Journal of Refractory Metals Ceramic materials; Laminated materials; SiC 1. Introduction Sand blasting treatment is an abrasive machining pro- cess and is widely used for surface strengthening 1, surface modification 2, surface clearing and rust removal 3,4, etc. It is suitable for the treatment of hard and brittle mate- rials, ductile metals, alloys, and nonmetallic materials. In the sand blasting process, a very high velocity jet of fine 1116, and the temperatures 17,18. Ceramics, being highly wear resistance, have great potential as the sand blasting nozzle materials. Several studies 11,15 have shown that the entry area of a ceramic nozzle exhibited a brittle fracture induced removal process, while the center area showed plowing type of material removal mode. As the erosive particles hit the nozzle at high angles (nearly 90C176) at the nozzle entry Erosion wear of laminated Deng Jianxin * , Liu Lili, Department of Mechanical Engineering, Shandong Universit Received 31 March 2006; Abstract SiC/(W,Ti)C ceramic nozzles with laminated structures were produced and exit region of the nozzle. Finite element method was used to coecients and shrinkage of the SiC and (W,Ti)C solidsolution the laminated ceramic nozzle was assessed by sand blasting; the results nozzle with the same composition. The experimental results have shown resistance to that of the homologous stress-free nozzles. 0263-4368/$ - see front matter C211 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijrmhm.2006.06.005 ceramic nozzles Jinlong, Sun Junlong y, Jinan 250061, Shandong Province, PR China accepted 30 June 2006 by hot pressing in order to reduce the tensile stress at the entry the residual stresses due to the dierent thermal expansion the sintering process of the composite. The erosion wear of were compared with those obtained with an unstressed reference that the laminated ceramic nozzles have superior erosion wear Materials 25 (2007) 263270 element method. The erosion wear ofthe laminatedceramic nozzles was investigated in comparison with an unstressed reference nozzle with the same composition. 2. Materials and experimental procedures 2.1. Preparation of SiC/(W,Ti)C laminated ceramic nozzle materials The starting materials were (W,Ti)C solidsolution pow- ders with average grain size of approximately 0.8 lm, pur- ity 99.9%, and SiC powders with average grain size of 1 lm, purity 99.8%. Six dierent volume fractions of (W,Ti)C (55, 57, 59, 61, 63, 65 vol.%) were selected in designing the SiC/(W,Ti)C laminated nozzle material with a six-layer structure. The compositional distribution of the laminated ceramic nozzle materials is shown in Fig. 2.Itis indicated that the compositional distribution of the lami- 264 D. Jianxin et al. / International Journal of Refractory Metals TiC : E 480 GPa; m 0:25; a 8:5C210 C06 K C01 ; k 21:4W=mK: SiC : E 450 GPa; m 0:16; a 4:6C210 C06 K C01 ; k 33:5W=mK: Owing to the symmetry, an axisymmetric calculation was preferred. Presume that it was steady state boundary conditions. The results of the distribution of the axial stresses in the GN-3 laminated nozzle in fabricating process at dierent showed higher cumulative mass loss under the same test conditions. The worn ceramic nozzles were cut after operation in longitudinal directions for failure analysis. Fig. 10 shows the photos of the inner bore profile of the GN-3 and CN-2 nozzles after 540 min operation. It is showed that inner bore diameter of the worn CN-2 nozzle along the nozzle longitudinal directions is larger than that of the worn GN-3 laminated nozzles, especially at the nozzle entry region. The results of the nozzle entry bore diameter variation with the erosion time of for GN-3 and CN-2 nozzles are shown in Fig. 11. It is indicated that the entry bore dia- meter enlarges greatly with the operation time for CN-2 stress-free nozzle. While the entry bore diameter increases slowly with the operation time for GN-3 laminated nozzle. Fig. 12 shows the comparison of the erosion rates for GN-3 and CN-2 nozzles in sand blasting processes. It is obvious that the erosion rate of the stress-free nozzles is higher than that of the laminated nozzles. 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