Milling time and sintering parameters optimization to fabricate ZrB2-30 vol% SiC composite with highest thermal shock resistance

The goal of this research is to investigate the thermal shock resistance of ZrB2-30 vol% SiC, consolidated by spark plasma sintering (SPS). So, ZrB2 and SiC powders were mixed with high energy mill for different milling time of 3, 9 and 15 h. Then sintering process was done for different soaking times (4, 8 and 12 min) and temperatures (1600, 1700 and 1800 degrees C) under the 40 MPa pressure. Thermal shock resistance was evaluated by water quenching method. The samples were placed in the furnace at various temperatures of 450 degrees C to 1600 degrees C, then cooled down in the water quickly. Flexural strength determined by three-point bending test before and after thermal shock cycle. The morphology of fracture was studied by scanning electron microscopy (SEM). According to the result, with the increase in the SPS temperature, the grain size was increased to some extent, and the microstructure was improved. Flexural strength increased due to porosity reduction, and the thermal shock resistance increased. Increasing the soaking time led to reduction in the flexural strength and thermal shock resistance. Finally, it was cleared that the milling ascent, improved the thermal shock resistance.