复合添加炭黑对低碳铝碳材料显微结构与性能的影响

以板状刚玉颗粒、活性氧化铝微粉、Si粉为主要原料,以N220或N990炭黑为碳源,以热固性酚醛树脂为结合剂,在埋炭条件下制备低碳铝碳材料,研究添加不同炭黑对所制得试样显微结构、抗折强度及热震稳定性的影响。结果表明,添加N220炭黑有利于促进材料的致密化和有效发挥纳米炭黑粒子对热应力的吸收作用,降低热冲击对材料结构的破坏,而添加N990炭黑有助于改善铝碳材料的孔结构,有利于试样在高温下形成长径比更大的碳化硅晶须,从而提高材料的力学性能;复合添加N220、N990炭黑能提高低碳铝碳材料试样的强度和抗热震性。材料热震后的抗折强度为7.44 MPa、残余强度保持率为53%~62%。

Effect of combined addition of carbon black on microstructure and properties of low carbon Al2O3-C refractories

Low carbon Al₂O₃-C refractories were prepared under carbon embedded atmosphere with tabular corundum particles, reactive alumina micro-powders and Si powders as the main raw materials, carbon black (N220 and N990) as the carbon source and thermosetting phenolic resin as the binder. The effects of addition of different kinds of carbon black on the microstructure,flexural strength and thermal shock resistance of the refractories were investigated. The results show that the addition of carbon black N220 can promote the densification of the material, effectively improve the thermal stress absorption capacity by the nano carbon black particles, and reduce the thermal shock damage in the material. With the addition of carbon black N990, the pore structure of the Al₂O₃-C refractories is refined, which is beneficial to the formation of SiC whiskers with larger length/diameter (L/D) ratio at high temperature,and therefore improve the mechanical properties of the material. In addition, the combined addition of carbon black N220 and N990 can improve the strength and thermal shock resistance of low carbon Al₂O₃-C refractories. The flexural strength and residual strength ratio of the material after thermal shock test are 7.44 MPa and 53%~62%, respectively.