【摘要】 研究了利用聚四氟乙烯作活化剂时Si/C混合粉末在氮气中燃烧合成Si3N4/SiC复合粉体。结果表明 :当聚四氟乙烯的加入量为 10 %(质量分数 )时可有效激励Si-C弱放热反应 ,使之以燃烧合成方式生成Si3N4/SiC复相粉。在埋粉条件下Si/C/SiC混合粉末也可以实现燃烧合成Si3N4/SiC复相粉。氮气参与反应时可进一步提高燃烧反应温度 ,并且首先以气相 -晶体生长机制生成Si3N4,然后在高温贫氮的反应前沿Si3N4分解 ,再与C反应生成SiC。在Si3N4/SiC复合粉中Si3N4形貌以晶须为主。综合X射线衍射分析、扫描电镜观察及原子力显微镜观察对实验结果进行了讨论 ,解释了Si3N4晶须的形成原理更多还原

【Abstract】 Combustion synthesis of Si₃N₄/SiC composite powders from Si/C powder mixture with the addition of polytetrafluoroe thylene（-C₂F₄-）_n as activator in pressurized nitrogen atmosphere was investigated. It is demonstrated that 10% （in mass） addition of （-C₂F₄-）_n can stimulate effectively the weak exothermic reaction between Si and C by self_sustaining combustion synthesis, and Si₃N₄/SiC composite powder can be formed even from Si/C/SiC compact sample . The combustion temperature can be enhanced further if the reaction is carried out in pressurized nitrogen atmosphere, where a sequential reaction takes place with the formation of Si₃N₄ via vapor_crystal mechanism as the first step followed by the decomposition of the nascent Si₃N₄ at the combustion wave zone and the reaction between Si and C, thus SiC is finally obtained. The Si₃N₄ morphology in the composite powder formed in N₂ is predominately in the form of whiskers in the as_synthesized Si₃N₄/SiC composites. The experimental results are discussed based on XRD analysis, SEM and AFM observation, and the formation mechanism of Si₃N₄ whiskers are explained then.更多还原