刚玉骨料种类对高纯刚玉制品性能的影响

Effect of corundum aggregate kind on properties of high purity corundum refractories

为对比电熔白刚玉和板状刚玉对高纯刚玉砖性能的影响,分别以粒度≤3 mm电熔白刚玉和板状刚玉为骨料,≤75μm的氧化铝粉和d_(50)≈3. 5μm的氧化铝微粉为基质,采用机压成型,分别于1 650、1 700、1 750和1 800℃保温3 h烧成制备了w(Al_2O_3)≥99. 0%的高纯刚玉试样。对两种烧后试样的常温和高温力学性能、高温蠕变性、抗热震性以及抗渣性进行了测定和分析。结果表明:无论是以板状刚玉还是电熔白刚玉为原料的高纯刚玉制品,其最佳烧成温度均为1 750℃;以板状刚玉为骨料制备试样的力学性能更优,抗渣渗透性更好,且试样的抗蠕变性好。分析原因主要为:板状刚玉颗粒结晶小,表面粗糙,骨料与基质的结合性好,显微结构中多为微细、非贯通气孔;电熔白刚玉中存在少量的β-Al_2O_3团聚体析晶物,高温蠕变时形成了较多液相。因此,以板状刚玉为骨料制备的高纯刚玉耐火制品综合性能更优。

High purity corundum brick specimens with w (Al2O3)≥99.0% were prepared using white fused corundum and tabular corundum (≤3 mm) as aggregates,alumina powder (≤75 μm) and alumina micropowder (d50≈3.5 μm) as matrix,machine-shaping,and firing at 1650,1700,1750 and 1800 ℃ for 3 h,respectively to compare the effect of two kinds of corundum aggregates on the properties.The mechanical properties at room temperature and high temperatures,hot creep resistance,thermal shock resistance and slag resistance of the fired specimens were measured.The results show that,1750 ℃ is the optimum firing temperature for high purity corundum refractories made of tabular corundum or white fused corundum.The specimens with tabular corundum aggregates have better mechanical properties,slag penetration resistance and creep resistance than ones with white fused corundum aggregates.The main reasons may be that the tabular alumina particles have small crystals and rough surfaces,thus the specimens with tabular corundum have non-interpenetrating micro-pores in the microstructure,and good combination between aggregates and matrix.There are a small amount of β-Al2O3 crystal agglomerates in white fused corundum,which form some liquid during hot creep.So the tabular alumina is the ideal raw material for high purity corundum refractories.