不同粒度莫来石球形骨料对Al_2O_3-SiO_2浇注料性能的影响

Effect of spherical mullite aggregates with different grain sizes on properties of Al_2O_3-SiO_2castables

由于球形骨料的流动性高,有利于致密堆积,可制备高性能耐火材料,因此,在以传统不规则形状莫来石骨料(以下称"传统骨料")、矾土均化料细粉、SiO_2微粉、纯铝酸钙水泥等为原料制备的低水泥Al_2O_3-SiO_2浇注料基础上,研究分别用粒度为8~5、5~3、3~1和≤1 mm的球形莫来石骨料(以下称"球形骨料")逐级取代同粒度的传统骨料对浇注料施工性能以及热处理后强度的影响,并借助SEM分析了试样的显微结构。结果表明:1)不同粒度球形骨料的引入均有效地改善了浇注料的流动性,降低了加水量,其中以引入3~1和5~3 mm的改善效果较好,使浇注料的加水量从采用传统骨料的5.8%(w)减少至5.2%(w);2)与传统骨料相比,除≤1 mm的球形骨料外,均可提高浇注料的可泵送性;3)球形骨料的引入提高了浇注料的致密度和常温耐压强度,但对浇注料的常温抗折强度影响不大,其中3~1 mm的球形骨料对浇注料强度的提升较大;4)热处理后浇注料的显微结构分析表明,球形骨料与基质边界结合紧密,与传统骨料的相当。

Compared with traditional aggregates,spherical aggregates have better flowability,which are in favor of dense packing and are expected to develop high performance refractories. Based on low cement AI2Q-SiO2 castables prepared with traditional mullite aggregates, homogenized bauxite powder, microsili- ca,and pure calcium aluminate cement,spherical mullite aggregates （8-5,5-3,3-1 and ≤1 mm） were used to replace the traditional aggregates with the same grain size, and the effect on workability and strength after heat treatment was researched. Microstructure of the specimens was analyzed by SEM. The results show that：（1）the introduction of the spherical aggregates with different grain sizes effectively im- proves the flowability of castables,and reduces the water requirement,especially,the introduction of 3 -1 and 5 - 3 mm spherical aggregates reduces the water requirement from 5.8% for the traditional aggregates to 5.2% ; （2） compared with the traditional aggregates, spherical aggregates improve the pumpability of castables except for ≤1 mm of spherical aggregates; （3）the introduction of spherical aggregates is favor- able for density and cold crushing strength of the castables, but has little effect on CMOR. The introduction of 3- 1 mm spherical aggregates enhances the strength of the castables obviously; （4）microstructure analysis shows in the heat-treated specimens, spherical aggregates have strong boundary bonding with the matrix,similar to the traditional aggregates.