超声波脉冲速度法研究镁铁铝材料的抗热震性

摘要

在高纯镁砂中分别添加一定量的电熔铁铝尖晶石和烧结铁铝尖晶石，制成化学组成相近的两种镁铁铝尖晶石试样，检测试样热震前及热震1～10次后的体积密度，并采用超声波检测仪检测超声波脉冲通过热震前试样及热震1～10次后试样的速度，进而计算试样热震前及热震1～10次后的弹性模量，用弹性模量随热震次数的衰减速率或保持率表征试样的抗热震性。结果表明：超声波脉冲通过两种镁铁铝试样的速度与试样经历的热震次数之间的关系较好地符合 ExpAssoc 函数；以烧结铁铝尖晶石制备的镁铁铝尖晶石试样的抗热震性比以电熔铁铝尖晶石制备的试样的好。%Two magnesia-hercynite specimens with the similar chemical composition were prepared through adding an appropriate amount of fused hercynite or sintered hercynite into high purity magnesia.The bulk density of the specimens endured 0 -10 cycles of thermal shocks was measured,respectively.The velocity of the ultrasonic pulse passing through the specimens endured different cycles of thermal shocks was test-ed.The elastic modulus of the specimens was calculated from the measured values of ultrasonic velocity. The degradation or retention of the elastic modulus vs the thermal shock cycles of the specimens was used to characterize the thermal shock resistance.The results show that an ExpAssoc approximation can be used to describe the changes of the ultrasonic velocities vs the thermal shock cycles.Compared with the specimen synthesized with fused hercynite,the specimen with sintered hercynite possesses better thermal shock resistance.