Fracture toughness and hardness investigation in ZrB2-SiC-ZrC composite

Goal of this research is survey the effect of ZrC on fracture toughness and hardness of ZrB2-30 vol%SiC. So, ZrB2-30 vol%SiC composites with different amount ZrC (4, 8 and 12 vol %) were SPSed at 1800 degrees C, for time of 9 min and under the pressure of 30 MPa. Microstructural evaluations were done by scanning electron microscopic (SEM). Densification was measured by Arashmidous method. Fracture toughness and hardness were determined by Indentation method and Macro-Vickers respectively. With increase in ZrC amount, SST rises from 1263 degrees C to 1345 degrees C and 1389 degrees C. Increase in ZrC addition up to 8 vol% resulted accompanied with hardness ascent nealy 5 GPa but in higher amount of 12 vol%, aslight decrease was happened. It was cleared with ZrC ascent up to 8 vol %, fracture toughness was enhanced from 4.8 MPa m(0.5) up to 6.6 MPa m(0.5), but with more addition up to 12 vol %, fracture toughness was decreased to 5.9 MPa m(0.5).