Abstract In this study, five mullite-corundum gas-permeable refractories reinforced by SiC whiskers were prepared with spherical porous mullite-corundum aggregates. The influence of the silicon powder content on the microstructure, phase composition, mechanical and gas-permeability properties were investigated through XRD, SEM and EDS. It was found that the silicon powder content strongly affected the mechanical and gas-permeability properties by changing the formation and distribution of mullite and SiC whiskers. SiC whiskers were formed both in the matrix and inside the pores of the aggregates. As the silicon powder content increased, the amount of SiC whiskers in the pores of the aggregates as well as at the aggregate/matrix interface increased, meanwhile more mullite was also formed at the interface. However, when the silicon powder content was larger than 9 wt%, much less mullite was observed at the interface, reducing the bonding between particles in the matrices. The formation of SiC whiskers and mullite at the interface improved the mechanical properties at a small expense of air permeability. The optimized refractory contained 6 wt% silicon powder which combined the highest cold and hot flexural strength (17.0 MPa and 10.2 MPa, respectively), as well as the best strain at fracture and a homogeneous gas permeability.

中文翻译：

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碳化硅晶须增强莫来石-刚玉透气耐火材料

摘要 本研究采用球形多孔莫来石-刚玉骨料制备了五种碳化硅晶须增强的莫来石-刚玉透气耐火材料。通过XRD、SEM和EDS研究了硅粉含量对显微结构、相组成、机械性能和透气性能的影响。研究发现，硅粉含量通过改变莫来石和 SiC 晶须的形成和分布，强烈影响机械和气体渗透性能。SiC 晶须在基体中和聚集体的孔内形成。随着硅粉含量的增加，聚集体孔隙中以及聚集体/基体界面处的SiC晶须数量增加，同时界面处也形成了更多的莫来石。然而，当硅粉含量大于 9 wt% 时，在界面处观察到的莫来石少得多，从而减少了基质中颗粒之间的结合。界面处 SiC 晶须和莫来石的形成以少量的透气性为代价提高了机械性能。优化的耐火材料含有 6 wt% 的硅粉，它结合了最高的冷热弯曲强度（分别为 17.0 MPa 和 10.2 MPa），以及最佳的断裂应变和均匀的气体渗透性。