Al_4O_4C的碳热还原合成及其反应动力学

CARBOTHERMIC REDUCTION SYNTHESIS AND REACTION DYNAMICS OF ALUMINUM OXYCARBIDE

以氧化铝(Al2O3)和石墨(C)为原料,采用碳热还原工艺合成铝氧碳(Al4O4C),借助于X射线衍射仪和场发射扫描电子显微镜研究了加热温度和保温时间对合成铝氧碳(Al4O4C)的影响。结果表明:提高加热温度,可加快Al2O3和C反应生成Al4O4C的反应速率;延长保温时间可增大Al2O3和C反应生成Al4O4C的反应程度。在反应初期主要为固-固反应,Al2O3和C直接接触反应生成Al4O4C和一氧化碳(CO);后期主要为气-固反应,Al2O3和CO气体反应生成Al4O4C和二氧化碳(CO2)。计算得到气-固反应的频率因子和活化能分别为338.66和264.19kJ/mol。

Aluminum oxycarbide（Al4O4C） was synthesized by a carbothermic reduction process using alumina（Al2O3） and graphite（C） as starting materials.The effects of heating temperature and keeping time on the synthesis of Al4O4C were investigated via X-ray diffractometer and field emission scanning electron microscope.The results show that the reaction speed and extent of Al2O3 and C in the formation of Al4O4C increase with the increasing of heating temperature and keeping time.The main reaction in the initial stage is solid-solid reaction.Al4O4C and carbon monoxide（CO） can be formed by the direct contact of Al2O3 and C.The main reaction is gas-solid reaction in the later stage,and Al2O3 and CO react in the formation of Al4O4C and carbon dioxide（CO2）.The calculation frequency factor and activation energy of the gas-solid reaction are 338.66 and 264.19 kJ/mol,respectively.