Al-MgAl_2O_4和Al-MgO-MgAl_2O_4体系中生成MgAlON的形貌

Morphology of MgAlON phases in Al-MgAl_2O_4 and Al-MgO-MgAl_2O_4 systems

为研究镁质原料对金属复合耐火材料中原位生成MgAlON形貌的影响,以金属Al粉为金属相,富铝尖晶石粉和电熔镁砂粉为镁质原料,固定Al粉加入量为30%(w),镁砂加入质量分数分别0、10%和30%(则镁铝尖晶石粉加入质量分数相应为70%、60%和40%),在埋炭条件下于1 350℃保温2 h烧后,利用SEM观察AlMgAl_2O_4和Al-MgO-MgAl_2O_4体系的试样中生成MgAlON相的显微形貌,并通过热力学分析探讨不同形貌MgAlON相的生成机制。结果表明:不加镁砂的Al-MgAl_2O_4体系中生成了板片状的MgAlON相,其形成机制为镁铝尖晶石参与反应的固-液-气或固-气反应。在加镁砂的Al-MgO-MgAl_2O_4体系中,加入少量(质量分数10%)镁砂时,生成了粒状和片状的MgAlON;镁砂加入量较多(质量分数30%)时,生成了粒状MgAlON,其形成机制为气-气反应,同时粒状MgAlON的粒径随着镁砂粉加入量的增多而增大。

In order to research the influence of magnesia based materials on morphology of MgAlON phases in-situ formed in metal composite refractories,aluminum powder was used as the metal phase,alumina-rich spinel powder and fused magnesia powder as starting materials to prepare metal composite refractories by keeping aluminum powder addition at 30 mass%, adding magnesia powder of 0, 10 mass% and 30 mass%, respectively （the corresponding additions of magnesium aluminate spinel powder are 70 mass%, 60 mass% and 40 mass% ） ,then carbon embedded firing at 13.50℃ for 2 h. The morphology of MgAlON phases in Al-MgAl2O4 and Al-MgO-MgAl2O4 systems was studied using SEM,and the formation mechanism of MgAlON phases with different morphologies was explained by thermodynamic analysis. The results show that tabular MgAlON phases form in the specimen without magnesia,and formation mechanism is sol- id-liquid-gas or solid-gas reaction with spinel material participated in. Granular and tabular MgAlON phases form in the Al-MgQ-MgAl2O4 adding 10 mass% magnesia. When adding 30 mass% magnesia,granular MgAlON forms, its formation mechanism is gas-gas reaction,and the particle size of the MgAlON phase increases with the magnesia addition increasing.