Erosion wear behaviours of SiC/(W,Ti)C laminated ceramic nozzles in dry sand blasting processes

In sand blasting processes, the nozzle entry region suffers form severe abrasive impact, which may cause large tensile stress and lead to an increased erosion wear at the nozzle entry area. In this paper, SiC/(W,Ti)C laminated ceramic nozzles were produced by hot pressing. The purpose is to reduce the tensile stress at the entry region of the nozzle. Due to the different thermal expansion coefficients and shrinkage of the SiC and (W,Ti)C solid-solution, the entry region of the SiC/(W,Ti)C laminated ceramic nozzles in the fabricating process exhibit a compressive residual stress. The value of this residual stress was calculated by means of the finite element method. The erosion wear behaviour of the laminated ceramic nozzle and of a stress-free nozzle, with the same composition, was assessed by dry sand blasting. Results showed that the laminated ceramic nozzles have superior erosion wear resistance to that of the homologous stress-free nozzles. 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, and leads to an improvement of erosion wear resistance. It is indicated that laminated structures in ceramic nozzles is an effective way to improve the erosion wear resistance of the stress-free nozzles. (c) 2006 Elsevier B.V. All rights reserved.