冲击板用镁质浇注料的组成对其性能的影响

Effects of composition of magnesia based castables for impact plate on its properties

以高纯镁砂、电熔镁砂、α-Al2O3微粉、亚白刚玉粉、镁铝尖晶石粉及SiO2微粉为原料,制备了冲击板用镁质浇注料。研究了添加MA尖晶石(质量分数分别为0、5%、8%、12%)及α-Al2O3微粉与亚白刚玉粉混合物(质量分数分别为5%、10%、15%、20%)对浇注料性能的影响。结果表明:(1)MA尖晶石添加量为8%时,经1550℃3h和1100℃3h烧后试样的抗折强度都比较高,两者强度比接近1,可判断材料的抗剥落性和抗热震性较好;固定MA尖晶石添加量为6%,α-Al2O3微粉与亚白刚玉粉混合物加入量在5%～10%范围内,试样高、中温烧后强度比更趋近1,具有更好的抗剥落性和抗热震性。(2)SEM分析显示了方镁石与MA尖晶石颗粒多呈直接结合,这有利于提高材料的高温强度。(3)添加的MA尖晶石作为晶核,能促进α-Al2O3微粉和亚白刚玉粉与MgO反应形成原位尖晶石,同时促进烧结和部分抑制MA尖晶石生成时过度的体积膨胀。

Magnesia based castables for impact plate was prepared with high purity magnesite, fused magnesite, α-Al2O3 micropowder, sub-white corundum powder, magnesia -alumina spinel powder and uf-SiO2 as staring materials. The effects of MA spinel additions （mass percent, 0,5% ,8% ,12% ） and the mixture addi- tions （mass percent： 5%, 10%, 15% ,20% ） of α-Al2O3 micropowder and sub-white corundum powder on thermal shock resistance of the castables were studied. The results show that. （ 1 ） When MA spinel addition is 8% ,MOR of the castables fired at t 550 ~C 3 h and 1 100 ~C 3 h are high and their ratio is about 1 ,which can prove the castables have good spalling resistance and thermal shock resistance. Keeping MA spinel addition at 6% ,the MOR ratio of specimens with 5% -10% of the mixture of α-Al2O3 micropowder and sub- white corundum powder fired at high and middle temperature is near t,so they have better spalling resistance and thermal shock resistance. （2）SEM analysis shows the direct bond between periclase and MA spinel is good for improving the hot strength. （3）MA spinel as crystal seed can accelerate reactions between MgO and α-Al2O3 micropowder and sub-white corundum powder forming in-situ spinel,and improve sintering and restrain partially the excess volume expansion caused by forming MA spinel.