纳米氧化铝超塑性及其对轻量刚玉材料微结构的影响

Superplasticity of Nano-alumina and Its Effect on the Microstructure of Microporous Alumina

高温工业炉衬耐火材料轻量化可大大降低工业窑炉能耗,对整个高温工业节能减排具有举足轻重的意义,也是目前国内外本领域所关注的重要课题,其关键在于形成大量微纳米封闭气孔。本文采用高温弹性模量、高温应力-应变等测试手段,首先对不同晶型纳米氧化铝的超塑性进行了对比研究;基于优势晶型纳米氧化铝超塑性,引入纳米铝溶胶,通过构建纳-微米双尺度烧结模型,制备了轻量刚玉材料。结果表明:与普通氧化铝微粉相比,纳米氧化铝表现出更好的高温超塑性,其中,纳米γ-Al_2O_3较为显著,其应变量为普通氧化铝微粉的3倍;引入纳米铝溶胶,发挥纳米氧化铝超塑性,可使材料闭口气孔率增加,体积密度降低,晶内气孔数量增加,制备出显气孔率较低、闭口气孔率较高、平均孔径较小的轻量微孔刚玉材料。

A lightweight industrial furnace wear lining refractory can greatly reduce the energy consumption and play a decisive role inthe high temperature industrial energy conservation; it is also one of the important issues that international refractory researchers focuson. The key challenge lies in the formation of closed micropores in prepared refractory materials. In this paper, firstly, the superplasticityof nano-alumina with different crystal types was investigated by means of high temperature elasticity modulus instrument and stress-strain gauge. Based on the superplasticity of nano-alumina with appropriate crystal type, lightweight alumina materials were fabricated byintroducing nano-alumina sol to form a pile-up of nano-micro double scales. Experimental results showed that compared to common aluminamicropowder, the nano-alumina exhibited better superplasticity. This is especially true for nano-sized y-A1203, whose elasticity modulus was3 times as high as that of common alumina micropowder. Owing to the superplasticity of nano-alumina sol, its introduction led to a lowerbulk density and an increase in closed porosity and quantity of intracrystalline pores of materials. Lightweight microporous alumina with lowapparent porosity, high closed porosity and small pore size could be obtained by introducing an appropriate amount of nano-alumina sol.