不同铝基原料对MgO-Al-C材料性能和显微结构的影响

以烧结镁砂骨料、电熔镁砂细粉、Al粉、N220炭黑为原料,酚醛树脂为结合剂,制备MgO-Al-C材料,研究了三种铝基原料(造粒氧化铝微粉、氧化铝空心微珠、六铝酸钙)对其常温抗折强度、高温抗折强度、抗热震性及抗氧化性的影响,并借助XRD和SEM对其物相组成及显微结构进行分析。结果表明,造粒氧化铝微粉是多孔结构,可吸收热应力,加入量为1%(质量分数,下同)时,可提高材料的常温抗折强度和抗热震性,明显改善材料的抗氧化性。氧化铝空心微珠是中空结构,可缓冲热应力,加入量为3%时,可明显提高材料的常温抗折强度,并具有较高的抗热震性和抗氧化性。六铝酸钙的热膨胀系数较低,可赋予材料较好的韧性,加入量不超过5%时,样品具有较好的抗热震性。

Effects of Different Aluminum-Based Materials on Properties and Microstructure of MgO-Al-C Materials

MgO-Al-C materials were fabricated using sintered magnesia aggregates, fused magnesia fine powder, Al powder, N220 carbon black as raw materials, and phenolic resin as a binder. The effects of three aluminum-based raw materials (granulated alumina micro-powder, alumina hollow micro-beads, calcium hexaaluminate) on the cold modulus of rupture, high modulus of rupture, thermal shock resistance and oxidation resistance of samples were investigated, the phase composition and microstructure were analyzed via SEM and XRD. The results show that granulated alumina micro-powder has a porous structure that can absorb thermal stress inside the MgO-Al-C materials. When the granulated alumina micro-powder is added at 1% (mass fraction, the same below), it can increase the cold modulus of rupture and thermal shock resistance of the MgO-Al-C materials, and significantly improve the oxidation resistance. Alumina hollow micro-beads has a hollow structure, which can buffer thermal stress inside the MgO-Al-C materials. When the added amount of alumina hollow micro-beads is 3%, the cold modulus of rupture of the MgO-Al-C materials can be significantly improved, and the material has high thermal shock resistance and oxidation resistance. Calcium hexaaluminate has a lower coefficient of thermal expansion, which can give the MgO-Al-C materials better toughness. When the added amount of calcium hexaaluminate is less than 5%, the MgO-Al-C materials have better thermal shock resistance.