红柱石粗颗粒预烧温度对莫来石-刚玉材料抗热震性的影响

Influence of pre-firing temperature of andalusite aggregates on thermal shock resistance of mullite-corundum refractories

为了研究经过预烧的红柱石粗颗粒对莫来石-刚玉耐火材料抗热震性的影响,将20%(w)的未经预烧或分别经1 300、1 400、1 500、1 600℃保温3 h预烧的南非红柱石粗颗粒(5～3 mm)分别与莫来石颗粒(3～1和≤1 mm)以及板状刚玉粉、活性氧化铝粉和SiO_2微粉配料,制样,于1 450℃保温3 h烧后制成莫来石-刚玉试样,检测其烧后线变化率、弹性模量、抗热震性,并进行显微结构分析。结果表明:随着红柱石粗颗粒预烧温度的提高,试样的常温抗折强度逐渐提高,但抗热震性能变差。这是由于随着红柱石粗颗粒预烧温度的提高,红柱石粗颗粒与基质的热膨胀系数差值变小,产生的微裂纹尺寸逐渐减小,且在热震过程中能够阻止新裂纹产生和裂纹扩张的微裂纹减少。

This work researches the effect of pre-fired andalusite aggregates on the thermal shock resistance of mullite-corundum refractories.Andalusite aggregates (5-3 mm) from South Africa (original or pre-firing at 1300 ℃,1400 ℃,1500 ℃ and 1600 ℃ for 3 h) were mixed with mullite particles (3-1 mm and≤1 mm),tabular corundum powder,active alumina powder and silica fume.The mixtures were shaped and fired at 1450 ℃ for 3 h into the mullite-corundum specimens.The linear change rate,elastic modulus and thermal shock resistance of the specimens were tested.The microstructure was analyzed.The results indicate that the cold flexural strength of the specimens increases gradually,but the thermal shock resistance gets worse with the rising preheating temperature of andalusite.The reasons are that with the rising pre-firing temperature,the difference between the thermal expansion coefficients of andalusite aggregate and the matrix decreases,so the generated microcracks get smaller,and the microcracks preventing the crack generation and growth during the thermal shock get less.