PTFE促发TiC陶瓷粉体低温固相合成研究

摘要

TiC powders were prepared at low temperature from the Ti-C system with polytetrafluoroethylene (PTFE) as a chemical activator. The reaction temperature, phase composition and morphology were determinedviadifferential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) to explore the reaction mechanism, respectively. The FESEM result shows that TiC powders with average particle size less than 100 nm are synthesizedvia low-temperature combustion synthesis at 530℃ by adding 3wt% PTFE into Ti-C system. Based on the most intensive diffraction peak (200) of the XRD pattern, the crystallite size of prepared TiC powders is calculated to be about 81 nm by the Scherrer formula, which is close to the average particle size observed from the FESEM image. It indicates that TiC particles consist of a single crystal as the result of fast, low-temperature, solid-state synthesis process. According to DSC results, the combustion synthesis mainly includes two reaction processes. Firstly, the initial reaction between titanium and PTFE particles releases a great amount of heat, and subsequently, the heat induced combustion reaction between titanium and carbon particles.%在 Ti-C 体系中引入 PTFE(聚四氟乙烯树脂)作为反应促进剂,实现了 TiC 粉体的低温固相合成。分别利用热分析仪、X-射线衍射仪和场发射扫描电子显微镜,测定了体系的反应温度,表征了生成物的物相和微观形貌,并对其反应过程和反应机理进行了分析。结果表明：当添加3wt% PTFE时,能够在530℃通过燃烧合成制备平均粒径小于100 nm的TiC陶瓷粉体,接近于利用Scherrer公式取XRD最强衍射峰计算出的平均晶粒尺寸81 nm,可以推测所合成的 TiC颗粒为单晶颗粒。燃烧合成过程分为两个步骤：首先,在低温下 PTFE和 Ti发生反应并释放出大量的热；然后,诱发Ti和C的固相反应生成TiC。