Fe--Sialon复合材料中 Fe3 Si 合成热力学分析及实验验证

对淤泥沙原料中Fe3 O4及其中间产物FeO和Fe可能参与的反应进行了热力学分析。结合绘制的不同CO分压下Fe-Si体系在C和SiO2过量下的优势区相图及Fe-O-N体系热力学参数状态图,得出体系中Fe元素最终以Fe3 Si形式存在,为淤泥沙合成O′-Sialon-SiC-Fe3 Si (即Fe-Sialon)复合材料提供了热力学理论依据。在热力学分析的基础上,以淤泥沙为主要原料,采用碳热还原氮化法制备了Fe-Sialon复合材料,并借助X射线衍射仪和扫描电子显微镜对烧结体的物相和显微形貌进行了表征,得出产物的主晶相为O′-Sialon,还含有少量的SiC和Fe3 Si相,晶粒呈现为纤维状、絮状或短柱状,与热力学分析结果( Fe元素最终以Fe3 Si存在)吻合。

Thermodynamic analysis and experimental confirmation of Fe3 Si synthesis in Fe--Sialon composites

A thermodynamic analysis was performed on possible reactions of Fe3 O4 in sediment material, intermediate product FeO, Fe, and other matters. In combination with the predominant area phase diagram of the Fe-Si system under different carbon mon-oxide partial pressures and excess carbon and silicon dioxide as well as the thermodynamic parameter state diagram of the Fe-O-N sys-tem, it is found that Fe finally exists in the form of Fe3 Si, which provides a thermodynamic theoretical basis for using sediment to syn-thesize O′-Sialon-SiC-Fe3 Si ( Fe-Sialon) composites. These Fe-Sialon matrix composites made from sediment were prepared by car-bothermal reduction-nitridation on the basis of thermodynamic analysis. X-ray diffraction and scanning electron microscopy results in-dicate that plentiful O′-Sialon phase and a small quantity of SiC and Fe3 Si phases appear in samples, and the crystalline grains are fi-ber-, cotton-, or short column-shaped, which is consistent with thermodynamic analysis results.