The Effect of Thermal Shock on Bending Strength of Zirconia Ceramics

This research aims to investigate the effect of thermal shock on bending strength of zirconia stabilized with 3% mol Yttria known as 3Y-TZP (Tetragonal Zirconia Polycrystal stabilized with 3 %mol Yttria). The zirconia powder with mean particle size of 0.2 - 2 µm was obtained from Good fellow UK. Zirconia powder was uniaxially pressed with a pressure of 100 MPa to produce cylindrical green body with a diameter of l5 mm and thickness of 8 mm and green body specimens of rectangular cross-section bar (8x5x50 mm3). The cylindrical green body was pressureless sintered at various temperature of 1250, 1300, 1350, 1400 and 1450 oC for 1 hour. The density of each sintered specimens was measured using Archimedes method. It was found that 1450oC was the best sintering temperature. The rectangular green bodies were then pressureless sintered in a furnace at temperatures 1450 oC for 1 hour with a heating rate of 5oC/min. The sintered samples were polished. Group of the sintered samples were then heated up with a heating rate of 5 oC /minute to various temperature of 25, 225, 275, 325 and 425 oC with a holding time of 1 hour. They were then thermal shocked by rapid cooling (quenching) to a water media with a temperature of 25 oC. The strength of samples was evaluated using four point bending test. The results shows that the thermal shock resistance of the specimen is 200 oC and 250 oC where the bending strength decreases drastically