Spectroscopic Study of Boundary Layer Between Electrode and Arc Plasma

为了进一步了解等离子体电弧过程，采用等离子体光谱法观察了电弧放电形态，分析了金属蒸气对直流和交流弧焊的影响。研究发现，电弧电压和阳极热输入随工作气压的升高而增大。阳极热输入和电弧压力受工作气体种类的影响。指出阳极热输入和电弧压力共同控制熔池金属蒸气现象。在交流电弧焊中，焊缝金属表面的情况可分为白区和亮区两种。对于各种铝合金，阴极斑点从焊池一直延伸到清洗区。此外，不同铝合金的阴极光斑数、半径和速度也不同。同时指出，铝合金的功函数和蒸气压对熔池金属蒸气的产生起着共同的控制作用。

In order to make a further understanding of plasma arc processes, we observed the arc discharge morphologies and analyzed the effects of metal vapor on D.C. and A.C. arc welding by means of plasma spectroscopic method.It is found that the arc voltage and anode heat input increase with elevating of working gas pressure. The anode heat input and arc pressure are influenced by kind of working gases. It is suggested that both anode heat input and arc pressure control the phenomena of metal vapor from weld pool.In A.C. arc welding, the conditions of weld metal surface can be classified into two types, the White zone and Bright zone. For all kinds of Al alloys, cathode spots extend from weld pool to cleaning zone. Besides, different cathode spot number, radius and velocity are observed with different Al alloys. It is also suggested that both work function and vapor pressure of Al alloy control the phenomena of metal vapor from weld pool.