Coefficients of elastic stiffnesses and thermal expansion of hot isostatically pressed, reaction‐sintered and technical fused‐mullite ceramics were measured between 100 and 1673 K in comparison with single crystal mullite employing resonant ultrasound spectroscopy and dilatometry, respectively. Additionally, chemical and phase compositions and the microstructure of the ceramics were studied using X‐ray diffraction techniques and scanning electron microscopy. Our studies revealed that despite polycrystallinity and slight porosity of up to 1.6%, the elastic behavior of the hot isostatically pressed ceramics is near to ideal aggregate elastic properties of mullite single crystal, for example, their bulk moduli fit within 0.7% to B = 170.0 GPa of single crystal mullite. On the other hand, with B = 155 GPa, the reaction‐sintered mullite behaves significantly softer. The difference can be explained with more tight grain to grain contacts in hot isostatically pressed ceramics as compared to reaction‐sintered materials. The thermal expansion of both types of ceramics almost coincides with the corresponding averaged behavior of single crystal mullite. For example, between 573 and 1273 K, the volume expansion coefficients of all these materials are (18.0 ± 0.3)·10⁻⁶ K⁻¹. Obviously, the microstructural features are less important for the macroscopic thermal expansion. Due to heterogeneous microstructure and high α‐alumina and zirconia contents, the corresponding properties of fused‐mullite refractory deviate strongly from those of the other mullite materials.

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莫来石陶瓷的热机械性能：新数据

与采用共振超声光谱法和膨胀计法测量的单晶莫来石相比，热等静压，反应烧结和工业熔融莫来石陶瓷的弹性刚度和热膨胀系数分别在100和1673 K之间。此外，还使用X射线衍射技术和扫描电子显微镜研究了陶瓷的化学和相组成以及微观结构。我们的研究表明，尽管多晶性和微孔率高达1.6％，热等静压陶瓷的弹性行为仍接近莫来石单晶的理想集合弹性，例如，它们的体积模量在0.7％以内，B  =  170.0 GPa单晶莫来石。另一方面，B  =  155 GPa，反应烧结的莫来石的行为明显较软。与反应烧结材料相比，热等静压陶瓷中的颗粒间接触更紧密，可以解释这种差异。两种陶瓷的热膨胀几乎与单晶莫来石的平均性能一致。例如，在573和1273 K之间，所有这些材料的体积膨胀系数为（18.0±0.3）·10 ^-6  K ^-1。显然，对于宏观的热膨胀，微观结构特征不那么重要。由于微观结构的异质性以及高的α-氧化铝和氧化锆含量，熔融莫来石耐火材料的相应性能与其他莫来石材料的性能有很大差异。