高强隔热刚玉-镁铝尖晶石-莫来石多孔陶瓷材料的制备

以氧化铝、石英粉和电熔镁砂为主要原料,以纸浆废液为结合剂,通过原位反应烧结制备复相高强隔热陶瓷,研究MgO添加量对所制备多孔陶瓷的显气孔率、抗折强度、耐压强度和抗热震性能的影响。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和电子万能试验机对材料的物相组成、显微结构和力学性能进行表征,并对多孔陶瓷的显气孔率和抗热震性能进行测试。结果表明:5%(质量分数)电熔镁砂与氧化铝、石英粉在1450℃下原位反应烧结3h可制备得到刚玉-镁铝尖晶石-莫来石多孔复相陶瓷,耐压强度达270.25MPa,抗折强度超过45MPa,同时显气孔率达26.46%,常温导热系数为1.469W·m^-1·K^-1,隔热性能良好,且3次热震后的残余抗折强度保持率超过27%,是极具应用前景的工业窑炉内衬材料。其中MgO含量变化会直接影响该多孔陶瓷三相组成、相形态、气孔孔径及分布,使得多孔陶瓷抗折强度、耐压强度和抗热震性能呈现非单调变化的规律。

Preparation of corundum-spinel-mullite porous ceramics with high strength and thermal insulation

Composite ceramics with high strength and thermal insulation were fabricated via an in-situ reaction sintering method using alumina,silica and fused magnesia as starting raw materials,and sulphite liquor as binders.The effect of MgO addition on apparent porosity,flexural and compressive strength,and thermal shock resistance of samples was investigated.The phase compositions,microstructure characteristics and mechanical properties were characterized by means of X-ray diffraction(XRD),scanning electronic microscopy(SEM)and electronic universal testing machine,the apparent porosity and thermal shock resistance of porous ceramics were also characterized.The results show that corundum-spinel-mullite porous composite ceramics are fabricated with 5%(mass fraction)fused magnesia,alumina,and silica sintering at 1450℃for 3h via an in-situ reaction.The porous ceramics possess high compressive strength of 270.25 MPa,high flexural strength of over 45MPa and apparent porosity of 26.46%.It exhibits good thermal insulation performance with a thermal conductivity of 1.469W·m^-1·K^-1 at room temperature,and the retention percent of residual flexural strength exceeds 27%after 3 thermal shocks.It is a promising lining material for kilns.The change of MgO content influences directly the three-phase compositions,phase morphology,pores size and distribution,which leads to non-monotonic variation of flexural strength,compressive strength and thermal shock resistance of the porous ceramics.