熔盐法制备Mo2C改性低密度C/C复合材料及其机理研究

Fabrication of Mo2C interlayer modified low-density C/C composite with molten salt method and study of the mechanism

摘要:

采用熔盐法对低密度C/C复合材料进行Mo2C改性,分析Mo2C的形成机理以及熔剂组成和反应温度对制备Mo2C改性C/C复合材料的影响,并研究了Mo2C改性对C/C复合材料微观组织结构的影响。结果表明：仲钼酸铵与C反应生成Mo2C的过程主要由三个阶段组成：仲钼酸铵分步分解为MoO3；MoO3还原为MoO2；MoO2与C反应生成Mo2C。适宜的反应参数为：以LiCl-KCl为熔剂,反应温度为1000℃。Mo2C颗粒在C相表面形核后首先形成花状聚集的Mo2C涂层,并随反应温度提高最终形成完整的Mo2C层。Mo2C与C界面结合良好,生成Mo2C过程的催化石墨化和应力石墨化作用使基体炭的有序度提高。

Abstract:

Low-density C/C composite was modified with Mo2C interlayers through molten salt method. The formation mechanism of Mo2C layers was analyzed; the effects of flux composition and reaction temperature on the abrication of Mo2C interlayers were studied; the influence of Mo2C-modification on the microstructure of C/C composite was also observed. Results show that the reaction between ammonium paramolybdate and C for the formation of Mo2C layers is mainly consist of three steps: decomposition from ammonium paramolybdate to MoO3, reduction of MoO3 to MoO2, carbonization of MoO2 to Mo2C. The appropriate flux of LiCl–KCl and the suitable reaction temperature as 1000℃ is determined according to the experimental results. Flower-like Mo2C layers are formed and then continuous Mo2C layer cover the surface of C phase with the increase of reaction time and temperature. The Mo2C/C interface showcases good bonding state. The pyrolytic carbon phase near the interface shows high order degree as the result of catalytic graphitization and stress graphitization. Modification of Mo2C interlayer for the C/C composite can facilitate the infiltration of Cu and its joining with Cu.