Abstract Two lightweight Al2O3-C refractories containing microporous corundum aggregates were fabricated by using flake graphite and microcrystalline graphite as the carbon source. The effect of these carbon sources on the microstructure and mechanical properties of lightweight Al2O3-C refractories with a silicon additive was then investigated. Using microcrystalline graphite resulted in more SiC whiskers in the microporous corundum aggregates compared to the specimens using flake graphite because microcrystalline graphite had a higher reactivity. The higher amount of SiC whiskers led to a more intertwined and compacter microporous aggregate/matrix interface structure. Due to the improved microporous aggregate/matrix interface together with the reinforcing effect of the well-developed SiC whiskers, the crack propagation along the aggregate/matrix interface was suppressed, whereas the percentage of cracks propagating within the aggregates was enhanced. Therefore, the lightweight Al2O3-C refractories using microcrystalline graphite had a similar apparent porosity of 24.5%, a similar bulk density of 2.71 g/cm3 but a 14.3% increased cold modulus of rupture (25.6 MPa), a higher fracture energy and a somewhat higher toughness than the ones using pricier flake graphite. Overall, the study provides a framework for the industrial application of lightweight Al2O3-C refractories with significantly improved mechanical properties.

中文翻译：

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不同碳源的轻质Al2O3-C耐火材料的显微组织和力学性能

摘要 以片状石墨和微晶石墨为碳源，制备了两种含微孔刚玉骨料的轻质Al2O3-C耐火材料。然后研究了这些碳源对含硅添加剂的轻质 Al2O3-C 耐火材料的微观结构和机械性能的影响。与使用片状石墨的试样相比，使用微晶石墨在微孔刚玉聚集体中产生更多的 SiC 晶须，因为微晶石墨具有更高的反应性。更高数量的 SiC 晶须导致更紧密和更紧密的微孔骨料/基质界面结构。由于改进的微孔骨料/基体界面以及发达的 SiC 晶须的增强作用，沿骨料/基体界面的裂纹扩展被抑制，而裂纹在骨料内传播的百分比得到提高。因此，使用微晶石墨的轻质 Al2O3-C 耐火材料具有相似的表观孔隙率 24.5%、相似的体积密度 2.71 g/cm3 但冷断裂模量 (25.6 MPa) 增加了 14.3%、更高的断裂能和稍微比使用价格较高的片状石墨的具有更高的韧性。总体而言，该研究为轻质 Al2O3-C 耐火材料的工业应用提供了一个框架，其机械性能显着提高。与使用价格较高的片状石墨相比，体积密度相似，为 2.71 g/cm3，但冷断裂模量 (25.6 MPa) 增加了 14.3%，断裂能更高，韧性稍高。总体而言，该研究为轻质 Al2O3-C 耐火材料的工业应用提供了一个框架，其机械性能显着提高。与使用价格较高的片状石墨相比，体积密度相似，为 2.71 g/cm3，但冷断裂模量 (25.6 MPa) 增加了 14.3%，断裂能更高，韧性稍高。总体而言，该研究为轻质 Al2O3-C 耐火材料的工业应用提供了一个框架，其机械性能显着提高。