Gradient structures in ceramic nozzles for improved erosion wear resistance

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, a (W,Ti)C/SiC gradient ceramic nozzle was produced by hot pressing. The purpose is to reduce the tensile stress at the entry region of the nozzle during sand blasting processes. The erosion wear behavior of the gradient ceramic nozzle was investigated in comparison with the common ceramic nozzles. Results showed that the gradient ceramic nozzles exhibited an apparent increase in erosion wear resistance over the common ceramic nozzles. The mechanism responsible was explained as the formation of compressive residual stresses in nozzle entry region in fabricating process of the gradient ceramic nozzles, which may partially counteract the tensile stresses resulting from external loadings. It is indicated that gradient structures in ceramic nozzles is an effective way to improve the erosion wear resistance of common ceramic nozzles.