电爆炸法制备纳米颗粒收集方法

Collection method for nanoparticles prepared by electric explosion

金属丝电爆炸法制备纳米材料因其负载可大程度的过热和爆炸产物非平衡扩散过程得到了研究人员的广泛关注,认为是制备新型功能材料的有效方法。研究了不同收集方法对电爆炸法制备钛纳米颗粒的影响,并结合电学、光学、自辐射图像和形貌分析等诊断手段分析了不同方法下产物特性的成因。结果表明,钛丝电爆炸呈现周期型放电模式,产物通道在放电结束前(约40μs)可膨胀至约1.7 cm处,此后有尖状突刺发展(波阵面后湍流区),其速度约为55 m/s。为研究爆炸产物不同状态下纳米颗粒形成特性,使用了3种不同的产物收集方法,分别为:①在金属丝径向1.5 cm处放置硅片收集;②在腔体出口处预置滤网收集;③在金属丝一侧电极上通过定向喷涂收集。产物形貌表征结果表明,使用不同收集方法时产物特征存在明显差别,前2种方法爆炸产物先与介质混合再沉积于硅片,得到的产物分别为分散、链状的球状纳米颗粒和密集、堆叠的纳米颗粒团簇;后一种方法电爆炸产物具有较高的密度和定向速度(对硅片),硅片以金属丝为轴心远近呈现出粉末状和烧结块状两种不同形式。

Using electrical explosion of wires to produce nanopowders has attracted wide interest because of the considerable overheat of the metal and the non-equilibrium process and it is considered to be an effective method to prepare expensive or difficult materials and powders with new properties.An experimental study on exploding Ti wire in atmosphere under a microsecond time-scale pulsed current was conducted.The influences of different collection methods on preparing Ti nanoparticles via electrical explosion were investigated.The reasons for different products characteristics were studied combined with the methods of electrical,radiant,self-emission images and the morphology characterization.Experimental results indicate that Ti explosion belongs to periodical discharge mode,the products channel expands to 1.7 cm before the end of discharge(about 40μs),and then there develops cuspate protrusions with a speed of 55 m/s.To investigate the formation characteristics of nanoparticles under different states of exploded products,three methods were used for collecting products,namely:①Placing a silicon wafer at 1.5 cm in radial direction;②Placing a silicon wafer on the exit of the cavity;③Collecting by directional spraying on one electrode of the wire.The characterization results of products morphology show that products have prominent discrepancies under different collection methods.Products of the former two methods mix with ambient medium and then sedimentate to the silicon,producing dispersive and catenulate nanoparticles and dense and stacked clusters respectively.For the last method,the exploded products possess relatively greater density and directed velocity(toward silicon wafer),presenting two forms as powders and sintered chunks(near the wire axis).