氧化镁晶须在镁质材料表界面的生长机制

Growth mechanism of magnesium oxide whiskers on the surface and interface of magnesium-based materials

采用烧结镁砂、电熔镁砂、硅微粉为原料制备了镁质浇注料,发现在镁质浇注料中引入碳化硅粉可在浇注料表界面形成纤维针状MgO晶须。对比分析了碳化硅细粉添加量和热处理温度对氧化镁晶须的影响,在低氧分压区域在达到1450℃以上时镁热还原反应导致镁蒸气迁移至材料表界面,氧化后析出MgO晶须。添加量为3%~7%的97%碳化硅细粉的镁硅质试样表面在1500℃热处理3 h容易集聚氧化镁晶须,且随着碳化硅添加量的增加,晶须生成量及发育情况均得到改善。

For the magnesia based castable made up with sintered magnesia,fused magnesia,and silica powder,it was found that the addition of silicon carbide powder can create fibrous needle MgO whiskers on the surface and interface of the castable.The impact of the dosage of silicon carbide fine powder and heat treatment temperature on magnesium oxide whiskers are compared and analyzed.When the temperature reached above 1450℃in the low oxygen partial pressure region,the magnesium thermal reduction reaction will cause the migration of magnesium vapor to the material surface and interface,and MgO whiskers grow after oxidation.The surface of magnesium siliceous samples with addition of 3%to 7%of 97%silicon carbide fine powder is prone to agglomeration of magnesium oxide whiskers after 3 hours of heat treatment at 1500℃.Moreover,as the dosage of silicon carbide increases,the generation and growth of whiskers are improved.