3Ti/Si/2C/0.2Al粉体在空气中燃烧合成Ti3SiC2

采用机械活化的3Ti/Si/2C/0.2Al单质粉体为原料，在空气中发生自燃反应，成功地合成了Ti₃SiC₂基材料. 采用XRD、SEM和EDS等手段,分析了合成产物的相组成和微观结构特征. 结果表明，机械合金化3Ti/Si/2C/0.2Al单质混合粉体，不仅细化了粉体颗粒，而且产生严重的晶格畸变，从而明显提高了粉体的反应活性. 把机械活化的粉体暴露在空气中，会发生剧烈的燃烧反应，并引发自蔓延反应，合成Ti₃SiC₂，冷却后变成多孔块体产物. 燃烧产物由Ti₃SiC₂、TiC和微量氧化物组成. 产物中Ti₃SiC₂含量约为83wt%. 产物表层比较致密和均匀，而内部则粗糙且多孔. 产物的表面是以Al₂O₃和TiO₂为主相的氧化膜，氧化物颗粒大小约为2~4μm. 氧化膜厚度约为5~10μm，比较致密. 内部为Ti3SiC2和TiC材料，板条状Ti₃SiC₂晶粒长约20~40μm，宽约2~4μm，发育完善. 粒状TiC晶粒大小约为3μm.

Combustion Synthesis of Ti3SiC2 in Air from 3Ti/Si/2C/0.2Al Powder Mixtures

Ti₃SiC₂ based material was successfully synthesized by self combustion in air using mechanically activated 3Ti/Si/2C/0.2Al powders as starting materials. Phase composition and microstructure of the material were characterized by means of XRD and SEM, the composition of sample was determined through EDX. Mechanical alloying of 3Ti/Si/2C/0.2Al powder mixtures may refine the powder particles and produce the severe lattice distortion, which significantly improves the reaction activities of the powders. When the powder mixture is exposed to the air, it self-ignited spontaneously and self-propagating high temperature synthesis (SHS) of titanium silicon carbide (Ti₃SiC₂) is induced. After cooling, a porous sample is obtained. The sample is composed of Ti₃SiC₂,TiC and tiny amounts of oxide. The content of Ti₃SiC₂ in the sample is about 83wt%. Surface of the sample is relatively uniform and dense, but the fracture is rough and porous. Surface layer of the sample consists mainly of Al₂O₃ and TiO₂ grains with a size of 24μm. The oxidation film thickness is 510μm. The inner of the sample is a mixture of Ti₃SiC₂ and TiC. Lath Ti₃SiC₂ grains are 2040μm in length and 24μm in width. TiC grains are about 3μm in dimension.