WEAR BEHAVIORS OF BORON CARBIDE CERAMIC NOZZLES IN DRY ABRASIVE BLASTING SURFACE TREATMENTS

摘要

Boron carbide nozzles were produced by hot pressing. The erosion wear behaviors of this nozzle caused by abrasive particle impact were investigated by dry abrasive blasting surface treatments. Silicon carbide and aluminum with different hardness were used as the erodent abrasive particles. Results showed that the hardness of the erodent particles played an important role with respect to the erosive wear. As the hardness of the erodent particles increases, there is a dramatic increase in erosion rate of the nozzles. The nozzle entry bore section suffered form severe abrasive impact under large impact angles. At the beginning, wear in the nozzle entrance section become a maximum, after several hours operation, a tapered shape entrance bore was developed. The wear mechanisms of the boron carbide nozzle in this area appeared to be entirely brittle in nature with the evidence of large scale chipping, and exhibited a brittle fracture induced removal process. On the nozzle center wall section, most of the particles traveled parallel to the nozzle wall, and the bore profile generally become convergent owing to a decrease in material removal rate. The wear mode in this area changed from impact to sliding erosion, and the wear mechanisms appeared to be the lateral cracking propagation due to a surface fatigue fracture mechanism.