高温氮气下镁碳耐火材料的物相重构与微结构演变  

Phase reconstruction and microstructure evolution of magnesia-carbon refractories at high temperatures in nitrogen

作　　者：闫明伟 杨裕民 仝尚好 张佳钰 孙广超 刘开琪[1,2] Yan Mingwei;Yang Yumin;Tong Shanghao;Zhang Jiayu;Sun Guangchao;Liu Kaiqi

机构地区：[1]中国科学院过程工程研究所多相复杂系统国家重点实验室,北京100190 [2]中科院过程工程研究所南京绿色制造产业创新研究院,江苏南京211135 [3]中航天水高新磨具有限公司,甘肃天水741024 [4]洛阳利尔功能材料有限公司,河南洛阳471039

出　　处：《耐火材料》2022年第2期93-100,共8页Refractories

基　　金：国家重点研发计划课题(2019YFC1904304);多相复杂系统国家重点实验室自主研究课题(MPCS-2021-C-01);中科南京绿色制造产业创新研究院资助(E0010717)。

摘　　要：以电熔镁砂、鳞片石墨和金属铝粉为原料,酚醛树脂为结合剂,在氮气气氛中,经1300~1600℃热处理后制备了镁碳耐火材料。分析了镁碳耐火材料的物相重构和微结构演变,揭示了化学气相沉积反应形成两种不同形貌氧化镁的机制。结果表明:在1300~1500℃时,试样的非氧化物组成为碳化铝(Al_(4)C_(3))、氮化铝(AlN)和镁铝氮化物(Mg_(3)Al_(n)N_(n+2),n=2或3);在1600℃时,热处理后试样中碳化铝和氮化铝的衍射特征峰值强度急剧降低,出现氮碳化铝(Al_(7)C_(3)N_(3))的尖锐衍射特征峰。铝热还原MgO和碳热还原MgO产生了Mg(g)。在试样表面,Mg(g)与氧气反应形成MgO晶须;在试样内部,Mg(g)与氧气发生CVD化学沉积反应形成立方MgO晶体。在热处理后试样的微区组织结构中,片状AlN与片状Mg_(3)Al_(n)N_(n+2)存在一定的位相关系,二者伴生存在,形貌难以区分。Magnesia-carbon refractories were prepared using fused magnesia,flake graphite and metal aluminum powder as starting materials,phenolic resin as the binder,heat-treating at 1300-1600℃in a nitrogen atmosphere.The phase reconstruction and the microstructure evolution of the obtained magnesia-carbon refractories were analyzed.The formation mechanisms of magnesia crystals with different morphologies by chemical vapor deposition were revealed.The results show that at 1300-1500℃,the non-oxides within the samples are aluminum carbide(Al_(4)C_(3)),aluminum nitride(AlN)and magnesium aluminum nitride(Mg_(3)Al_(n)N_(n+2),n=2 or 3);at 1600℃,the diffraction characteristic peak intensity of Al _(4)C_(3) and AlN decreases sharply,and sharp diffraction characteristic peaks of nitrogen aluminum carbide(Al_(7)C_(3)N_(3))appear.Mg(g)is produced by the aluminothermic reduction and carbothermal reduction of magnesia.On the surface of the samples,Mg(g)reacts with oxygen to form MgO whiskers.Inside the samples,Mg(g)and O_(2)(g)undergo a CVD chemical deposition reaction to form cubic MgO crystals.There is a phase relationship between flake AlN and flake Mg_(3)Al_(n)N_(n+2),and they are so associated with each other that the morphology is difficult to distinguish.

关 键 词：镁碳耐火材料 物相重构 非氧化物 氧化镁 

分 类 号：TQ175[化学工程—硅酸盐工业]