加入纳米碳酸钙对铬刚玉浇注料力学性能的影响

Effect of Nano-CaCO_3 on mechanical property of chrome-containing corundum castables

以板状刚玉、氧化铝微粉、氧化铬微粉(平均粒径<5μm)、铝酸钙水泥(Secar 71)、商品纳米碳酸钙(平均粒径<100 nm)为主要原料,FS10为减水剂,制备了不同纳米碳酸钙加入量(0、0.2%、0.4%、0.6%、0.8%、1%)的铬刚玉浇注料试样,测定了其经1 000及1 600℃热处理后的显气孔率、体积密度和强度,并用扫描电子显微镜(SEM)观察了材料的微观结构。结果表明,在减水剂加入量一定时,随纳米碳酸钙加入量的增大,浇注料的流动性显著下降,显气孔率逐渐升高,冷态和热态强度逐渐降低;在浇注料流动值基本一致的情况下,随纳米碳酸钙加入量的增大,浇注料的显气孔率明显增大,但其冷态和热态强度皆逐渐提高,这主要是由于纳米碳酸钙在高温下分解产生的CaO和结构中的A l2O3原位反应形成铝酸钙物相的缘故。

The chrome-containing corundum castables specimens with different nano-CaCO3 additions （0,0.2%, 0. 4% ,0.6% ,0.8% and 1 % ） were prepared using tabular corundum, alumina micropowder, chrome oxide micropowder （average particle size 〈 5 μm）, calcium aluminate cement （ Secar 71 ）, commercial nano- CaCO3 （average particle size 〈100 nm） as main starting materials and FSIO as water reducer. The specimens heat treated at 1000 ℃ and 1600 ℃ were characterized in terms of apparent porosity, bulk density, strengths and microstructure. The results show that： （1）when the water reducer addition is kept invariable, with increase of nano-CaCO3 addition, the flowability of the castables becomes poor, apparent porosity gradually increases, and cold and hot strengths gradually decrease; （2）when the flowability of the castables is at similar level, apparent porosity noticeably increases, cold and hot strengths gradually increase,which is mainly attributed to calcium aluminate formation from the in-situ reaction between Al2O3 and CaO derived from decomposition of nano-CaCO3 at high temperature.