机械化学还原法制备Al_2O_3-Mo_3Si/Mo_5Si_3纳米复合粉体

Preparation of Al_2O_3-Mo_3Si/Mo_5Si_3 nanocomposite powders by mechanochemical reduction method

以MoO3、Si粉和Al粉为原料,采用机械化学还原法制备了Al2O3-Mo3Si/Mo5Si3纳米复合粉体.利用X射线衍射(XRD)、激光粒度分析仪(LPS)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和差热-热重分析(DTA-TG)等对复合粉体和球磨过程中粉体的固态反应过程进行表征.结果显示,MoO3-Si-Al混合粉体球磨5h后转变为Al2O3-Mo3Si/Mo5Si3复合粉体,反应为机械诱导的自蔓延反应.球磨20h后,Mo3Si、Mo5Si3和Al2O3的晶粒尺寸分别为27.5、23.3和31.8nm,产物具有纳米晶结构,粉体平均粒度为3.988μm,颗粒呈球形,分布均匀.DTA分析表明,复合粉体在机械化学反应过程中首先发生MoO3和Al之间的铝热反应,之后将发生一系列Mo和Si之间的反应,生成Mo5Si3和Mo3Si.

Al2O3-Mo3Si/Mo5Si3 nanocomposite powders were synthesized by mechanochemical reduction method with MoO3,Si and Al powders as raw materials.The solid-state reaction process and synthesized composite powders were investigated by XRD,laser particles size analytic instrument,TEM,SEM and DTA-TG method.Experimental results indicated that Al2O3-Mo3Si/Mo5Si3 composite powders were obtained by milling of MoO3-Si-Al powders for 5 h by the mechanical induced self-propagating reactions.The grain sizes of Mo3Si,Mo5Si3 and Al2O3 were 27.5 nm,23.3 nm and 31.8 nm respectively after milling of 20 h.The composite powders possessed nano-crystalline structure and the average particle size was 3.988 μm,with spherical shapes and uniform distribution after 20 h.DTA analysis results showed that the first reaction was a thermite reaction of MoO3 and Al in the milling process,followed by a series of reactions to form Mo3Si and Mo5Si3 in the Mo-Si system.