熔盐介质中制备镁橄榄石轻质材料的机理

Preparation Mechanism of Lightweight Forsterite Materials in Molten Salt Media

以天然镁橄榄石和复合熔盐Na2CO3+NaCl为原料,经过900～1200℃反应烧结10 h以及蒸馏水溶解熔盐处理等过程,获得具有小尺寸气孔、较高强度的镁橄榄石轻质材料。采用X射线衍射(XRD)分析物相组成及变化,扫描电子显微镜(SEM)观察材料的显微结构包括气孔大小及分布情况。结果表明:反应制备的烧结体在由原始Na2CO3-NaCl组成熔盐体系中,随着混合盐加入量的减少,经洗盐处理后的试样耐压强度增加,体积密度相应增加,而显气孔率减少;试样制备过程主要是盐熔化后,经过水溶解处理后,其占据的空间将形成气孔,而熔盐体系中Na2CO3会分解,CO2从烧结试样中逸出,从而烧结体中也形成了孔隙;混合盐与天然镁橄榄石中含铁杂质反应,生成可溶于水的化合物,在水处理阶段移出烧结体外。

High-strength lightweight materials with small-size pores were prepared using natural magnesium forsterite and composite Na2CO3＋NaCl molten salt as raw material.The specimens were treated at 900-1200 ℃ for 10 h,and then dissolved in distilled water.The phase composition and change were determined by X-ray diffraction analysis（XRD）,and pore size and distribution of microstructure of products were observed by scanning electron microscope（SEM）.The results showed that the sintered body was prepared by the composition of the original Na2CO3-NaCl molten salt,with the addition of mixed salt reduction,the compressive strength and bulk density of distilled water treated samples were increased,but the porosity of samples were reduced.The space of sintered materials were occupied by molten salt,after water-soluble,its occupied space formed pores,Na2CO3 was also broken down in the molten salt system,CO2 escaped from the sintered samples,so that the same porous were formed.The natrium element of mixed salt and natural part of forsterite impurities reacted,and the water-soluble compounds was dissolved in water,then getting out of the sintering body.