添加剂对MgO-CaO浇注料性能的影响

Influence of additive on properties of MgO-CaO castables

以36％（质量分数，下同）的镁钙砂（5～3mm）、16％的镁钙砂（3～1mm）和20％中档镁砂（≤1mm）为骨料，21％～28％的高纯镁砂粉（≤0．088mm）为细粉，外加3％的硅灰为结合剂，分别比较了不同量的3种添加剂ZrO2（分别为2％、4％、6％）、Al2O3（分别为3％、5％、7％）、TiO2（分别为2％、4％、6％）对MgO—CaO浇注料性能的影响。结果表明：加入ZrO2可提高MgO—CaO浇注料的体积密度和常温抗折强度，Zr02含量为4％的效果最好；加入Al2O3时，随Al2O3量的增加，MsO—CaO浇注料的体积密度和常温抗折强度增大，但高温下形成的低熔点铝酸盐相也较多，可能导致材料的高温性能下降，综合考虑认为，Al2O3以添加3％较好；加入TiO2可显著促进材料的烧结，使其结构致密，体积密度提高，常温抗折强度提高，TiO2含量为2％～4％时，对改善材料性能的作用较理想，但超过4％时，材料的性能开始变差；添加剂ZrO2、Al2O3、TiO2均能改善MgO—CaO浇注料的抗热震性，其中，添加ZrO2的试样抗热震性最好，其次为加Al2O3的加TiO2的稍差。

Magnesia - calcia castables were prepared with 36% MgO - CaO clinker （5 - 3 mm）, 16% MgO - CaO clinker（3- 1 mm） and 20% middle grade magnesite （≤1 mm） as aggregate,21% -28% high purity magnesite powder （≤0.088 mm） as fines,silica fume as binder. The influence of additives such as ZrO2 （2% ,4% ,6%, respectively）, Al2O3 （ 3%, 5%, 7%, respectively ）, TiO2 （ 2%, 4%, 6%, respectively ） on the properties of MgO -CaO castables has been studied. The results indicate. （1）Adding ZrO2 can enhance bulk density and cold modulus of rupture of MgO -CaO castables. The optimum addition of ZrO2 is 4%. （2） With the increase of AI2Q addition, bulk density and cold modulus of rupture increase, but the amount of low-melting aluminate phase formed at high temperature increases which may result in decreasing high temperature properties. The optimum addition of AI20~ is 3%. （3）Adding TiO2 can accelerate the sintering obviously which results in the densification of the structure and the increase of bulk density and cold modulus of rupture. The properties of the castables are better when the addition of TiO2 is 2% N4%. But the properties will decrease when the addition of TiO2 is more than 4%. （4）Thermal shock resistance of MgO - CaO castables can be improved by adding ZrO2,Al2O3 and TiO2,and ZrO2 has the best effect,then Al2O3 and the last TiO2.