热处理温度对MgO--MgAl_2O_4--ZrO_2共晶材料力学性能的影响

Effect of Heat Treatment Temperature on Mechanical Properties of MgO--MgAl_2O_4--ZrO_2Eutectic Materials

以分析纯的MgO、活性α--Al2O3、电熔单斜ZrO2和电熔镁砂为原料,研究了热处理温度对MgO--MgAl2O4--ZrO2共晶材料力学性能和热震稳定性的影响。结果表明:随热处理温度从1 650℃提高到1 740℃,MgO--MgAl2O4--ZrO2共晶体的生成比例逐渐增加,材料断裂韧性、断裂表面能、高温抗折强度和抗热震稳定性逐渐提高。经过1 740℃热处理后,MgO--MgAl2O4--ZrO2共晶材料的力学性能明显改善,其断裂韧性、断裂表面能、高温抗折强度分别为MgO--Al2O4--ZrO2非共晶材料的1.65倍、2.04倍、5.91倍,MgO--ZrO2材料的1.49倍、1.72倍、2.22倍。MgO--MgAl2O4--ZrO2共晶材料因能吸收裂纹并阻止裂纹扩展而具备优异的抗热震稳定性能,其抗热震稳定性参数Rst值和R′′′′值分别为MgO--MgAl2O4--ZrO2非共晶材料的1.29倍、1.81倍,MgO--ZrO2材料的1.50倍、3.29倍。

The effect of heat treatment temperature on the mechanical properties and thermal shock resistance of MgO- MgA12 O4-ZrO2 eutectic materials was investigated using analytically pure MgO, active a-A1203, fused m-ZrO2 and fused mag- nesia as raw materials. The results show that the proportion of generated MgO-MgA12 O4-ZrO2 eutectic materials increases with increasing the heat treatment temperature from 1 650 ℃ to 1 740℃, and its fracture toughness, fracture surface energy, high-temperature modulus of rupture and thermal shock resistance are improved gradually. The mechanical properties of MgO- -MgA12 O4-ZrO2 eutectic materials at I 740 ℃ are improved. The fracture toughness, fracture surface energy and high-temper- ature modulus of rupture of MgO-MgA1204-ZrO2 eutectic materials are 1.65 times, 2.04 times and 5.91 times greater than those of MgO-MgA12 O4-ZrO2 noneutectic materials, respectively, and they are 1.49 times, 1.72 times and 2.22 times greater than those of MgO-ZrO2 materials, respectively. The MgO-MgAl2O4-ZrO2 eutectic material has a superior thermal shock re- sistance since this material absorbs the cracks and prevents the crack propagation. The thermal shock resistance parameters, i. e. , Rst andR＇＂ values, are 1.29 times and 1.81 times greater than those of MgO-MgA1204-ZrO2 noneutectic materials, re- spectively, and they are 1.50 times and 3.29 times greater than those of MgO-ZrO2 materials, respectively.