Development of SiC/(W,Ti)C Gradient Ceramic Nozzle and Study on Its Erosion Mechanism

Idea of functionally gradient material(FGM) theory was used to the design of ceramic nozzle.The purpose was to reduce the stress at the entrance of the nozzle during abrasive jet machining process.The stress states of the nozzle were analyzed by finite element method.Results show that the minimum stress appeared in entrance area of the gradient ceramic nozzle,and so SiC/(W,Ti)C gradient ceramic nozzle were produced.The erosion behavior of the SiC/(W,Ti)C gradient ceramic nozzle was investigated in comparison with common ceramic nozzles.The SiC/(W,Ti)C gradient ceramic nozzles exhibited an apparent increase in erosion wear resistance over the common ceramic nozzles under the same test conditions.This is because that the stress state at gradient ceramic nozzle was changed and its mechanical properties were improved.The wear mechanism of gradient ceramic nozzle was fatigue and fracture at nozzle entrance,micro-cutting between extrance and exit,and fracture due to fatigue and brittle fracture.