原位自生Al_2O_3-TiC_p/Al基复合材料的热力学分析

采用熔铸法制备了原位自生Al2O3-TiCp/Al基复合材料。借助差示扫描量热仪(DSC)、扫描电子显微镜(SEM)、能谱分析仪(EDS)、X射线衍射仪(XRD)等测试技术,对Al-TiO2-C体系的热力学进行了详尽的分析,讨论了过量铝对Al-TiO2-C体系反应的影响。结果表明,通过控制反应温度等工艺参数完全可以获得原位自生Al2O3-TiCp/Al基复合材料,避免副产物Al3Ti和Al4C3的产生。Al-TiO2-C体系原位合成Al2O3-TiCp/Al基复合材料存在着复杂的化学反应。首先在无过量铝的情况下,Al与TiO2发生置换反应,生成了Al2O3和游离态[Ti],而后游离态[Ti]与C结合生成TiC;而存在过量铝的情况下,首先发生铝热反应生成Al3Ti,进而Al3Ti与C结合生成TiC。最终完全获得Al2O3-TiCp/Al复合材料。随着过量Al含量由0增加至70%,Al与TiO2反应生成Al2O3的反应起始温度不断降低。

Thermodynamic Analysis of In-situ Al_2O_3-TiCP/Al Composites by MC Technique

The in situ Al_2O_3-TiCp/Al composites were successfully fabricated by melting and casting technique in the Al-TiO_2-C system. The thermodynamic mechanism of the composites was investigated by means of DSC and SEM and EDS and XRD techniques et al. The results showed that the ideal composites can be obtained by controlling and adjusting process parameters, avoiding to formation of Al_3Ti and Al_4C_3. the chemical reactions were complicated in the Al-TiO_2-C system. Little overdose aluminum caused that the displacement reaction occurred between Al and TiO_2 with releasing much heat, and Al_2O_3 and free Ti were formed, then the active Ti combined with C and produced TiC; more overdose aluminum caused the thermit reaction happened between Al and TiO_2, and was generated, then Al_3Ti combined with C and produced TiC. With the overdose aluminum increasing, the initial reaction temperature between Al and TiO_2 decreased.