添加熔融石英对MgO材料抗热震性的影响

研究了不同粒度的熔融石英对MgO材料抗热震性的影响，采用XRD和SEM进行了矿物组成和显微结构分析，同时比较了热震前后试样孔径分布的变化。结果表明，加入熔融石英颗粒的试样，热震后抗折强度和耐压强度保留率明显大于未添加试样和添加熔融石英细粉试样的强度保留率。添加熔融石英后试样的热膨胀系数变小，高温下熔融石英粉易与MgO反应生成镁橄榄石，促进了试样烧结使致密度提高，由于热膨胀系数不匹配因而在熔融石英颗粒周边形成明显的微裂纹圈。因为微裂纹吸收热应力的作用，所以，加入熔融石英颗粒和细粉可以提高MgO材料的抗热震性，相比之下，添加熔融石英颗粒时效果更明显。

The Effect of Fused Silica Addition on Thermal Shock Resistance of MgO Material

The property of the thermal shock resistance of MgO material which was added fused silica of different particle sizes was studied, the mineral composition and microstructure was analyzed respectively by XRD and SEM. Meanwhile, the aperture distributions of samples before and after the thermal shock were compared. The result indicates that the retaining rate of CCS and MOR of the samples which were added fused silica particle is obviously greater than that of the original samples and the sample which added fused silica powder. The thermal expansion coefficient of the sample becomes smaller after adding the fused silica. Under high temperature, the fused silica reacted with MgO and generated M2S, which accelerated the sintering of sample and improved its density. Because of the mismatch of the thermal expansion coefficient, there is a circle of microcrack appeared. And because the microcrack absorbs the thermal stress, the thermal shock resistance of MgO material can be improved when adding the fused silica particle and powder. Especially, fused silica particles have obvious effect on improving the thermal shock resistance of MgO material