Abstract: Mullite-SiC brick recycled aggregates (MSRA) have high water absorption and apparent porosity,which limits their extensive application in refractory castables.In this work,Al₂O₃-SiC-C castables were fabricated using brown alumina,alumina sol modified MSRA,silicon carbide,white fused alumina,and reactive alumina as the primary raw materials.The influences of the alumina sol modified MSRA addition (0,14%,18%,22%,26%,and 30%,by mass) on the properties of the castables were investigated.The results indicate that alumina sol can generate an Al₂O₃ coating on the surface of MSRA,which fills the internal pores of recycled aggregates and reduces the water absorption.After heat treating at 1 450 ℃,the castable achieves the optimal comprehensive performance at an alumina sol modified MSRA addition of 18%:the corresponding bulk density,apparent porosity,cold modulus of rupture,cold compressive strength,and MOR retention ratio after thermal shock are 2.98 g·cm^-3,16.7%,17.4 MPa,73.3 MPa,and 36%,respectively.The alumina sol modified MSRA facilitates the in-situ formation of mullite at the aggregates-matrix interface,which can effectively deflect cracks,prolong crack propagation paths,and consequently improve the thermal shock resistance of the castables.

Key words: mullite-SiC brick, recycled aggregates, alumina sol, Al₂O₃-SiC-C castables

摘要： 废弃硅莫砖再生骨料(MSRA)较高的吸水率和显气孔率限制了其在耐火浇注料中的广泛应用。以棕刚玉、铝溶胶改性MSRA、碳化硅、白刚玉和活性氧化铝为主要原料,制备了Al₂O₃-SiC-C浇注料。研究了铝溶胶改性MSRA添加量(质量分数分别为0、14%、18%、22%、26%和30%)对该浇注料性能的影响。结果表明:铝溶胶可在MSRA表面生成一层Al₂O₃涂层,填充硅莫砖再生骨料孔隙,降低吸水率。经1 450 ℃热处理后铝溶胶改性MSRA添加量为18%(w)时,浇注料的体积密度、显气孔率、常温抗折强度、常温耐压强度及热震后的抗折强度保持率分别为2.98 g·cm^–3、16.7%、17.4 MPa、73.3 MPa和36%,各项性能最优。铝溶胶改性的MSRA在骨料基质界面处原位形成了莫来石,可有效偏转裂纹,增加裂纹扩展路径,提升浇注料的抗热震性能。

关键词: 硅莫砖, 再生骨料, 铝溶胶, Al₂O₃-SiC-C浇注料