Cavitation erosion in coal fly ash-based glass-ceramics

Coal fly ash-based glass-ceramics were produced by the sinter-crystallization of secondary raw materials derived glasses, and their resistance to cavitation erosion was investigated. Four different glasses were prepared using fly ash and fly ash-glass cullet mixtures with different CaO sources. The viscosity behavior of the parent glasses was analyzed using hot-stage microscopy and the Vogel-Fulcher-Tammann equation. Mechanical properties were determined and correlated with cavitation resistance. Cavitation erosion behavior was evaluated using the ultrasonic vibration method in accordance with ASTM G32. The cavitation rate ranged from 0.0013 to 0.0079 mg/min. SEM analysis revealed that cavitation damage occurred mainly through pit formation. The results indicate that cavitation resistance is governed not only by hardness, but also by the balance between hardness and fracture toughness. The study demonstrates that coal fly ash can be successfully used to produce glass-ceramics with good cavitation resistance.