摘要:
丝电爆制备纳米粉时,电流从电极导入金属丝的过程直接影响电极烧损和粉末中微米级大颗粒产生.分别通过接触和气体放电两种方式导入电流进行电爆试验.结果表明,光测量装置检测到的丝端部光电流几乎与回路放电电流同时产生,而中间位置的光电流则要滞后一段时间;由探针收集的产物确定,金属丝端部主要形成熔融粒子,中间部分主要形成气相粒子.分析可知,接触方式导入电流时,丝端部也存在气体放电现象,大电流主要通过气体放电形成的等离子体导入.等离子体对电流的旁路作用会阻碍能量向金属丝沉积,这是产生微米级大颗粒和＂积瘤＂主要原因.通过气体放电方式导入电流时,电极烧损明显减轻,并可以避免＂积瘤＂产生.
关键词:
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丝电爆
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气体放电
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光照度
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能量密度
Abstract:
In the process of nanopowder production by the wire electrical explosion,the ablation of electrodes and the formation of micronsize particles are directly influenced by the way the current is injected into the metal wire from the electrodes.Through the channels which are provided by the ＂contact＂ between the electrodes and the wire ends,as well as the ＂breakdown＂ between them,a series of experiments of electrical explosion is carried out.Results show that the photocurrent detected by photodiodes at the wire ends almost occurs simultaneously with the circuit discharge current,however it at the central section lags behind the circuit discharge current obviously.The initial explosion product of the wire ends is liquid,and that of the other parts of wire is gas.Those results indicate that when the current folows into the ＂contact＂,the phenomenon of gas discharge also occurs at the wire ends.Because the plasma provides another current path,the energy density of the wire ends is decreased.Hence,the wire ends cannot explode and form remainder on the electrodes.When the current flows into the ＂breakdown＂,the electrodes ablated is slightly obvious,and there was no remainder on the electrodes.
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