Advanced Pulsed Wire Discharge Technologies for Nanosized Powder Synthesis

Summary form only given. Pulsed wire discharge (PWD) has been proved an effective method for synthesizing nanosized powders of metal or various compound materials. In order to widen the application fields of PWD, advanced technologies are being developed for powder size control and chemical reaction enhancement. The size of particles synthesized by PWD is basically determined by the gas pressure if the PWD plasma is generated in a constant-pressure ambient gas. However, this can be changed by using a time-varying pressure so that both the average powder size and the size distribution profile can be controlled within a certain range. In the experiment, a high-speed gas puff is used to provide the high gradient of the ambient gas pressure during the wire explosion. Experimental results have shown that smaller particle size and narrower size distribution can be obtained by applying a gas puff to PWD. In order to enhance the chemical reaction between the ambient gas and the wire material, preionization technology has been developed to create active gas species before the nanosize powders are formed. It is initially tested in the experiment for enhancement of nitridation of aluminium nitride powders