Fabrication and Performance of Symmetrical Gradient Ceramic Nozzles

Abstract

A model for the design of symmetrical gradient ceramic nozzles is presented. The purpose is to form compressive residual stresses at the entry and exit of the ceramic nozzle, and to reduce the erosion wear at these areas during abrasive air-jet machining. A SiC/(W,Ti)C ceramic nozzle with symmetrical gradient structure at its entry and exit was produced by hot pressing. The residual stresses inside this layered nozzle in the fabricating process were calculated by means of the FEM. The mechanical properties at individual layers were measured, the microstructure was examined. The erosion wear of this symmetrical gradient ceramic nozzle was investigated and compared with an unstressed reference nozzle. The production of symmetrical gradient structures with compressive residual stresses within the entry and exit of the nozzle has been proved to be a suitable way to obtain ceramic nozzles with superior erosion resistance.