Spectroscopic Study of Boundary Layer Between Electrode and Arc Plasma

为了进一步了解等离子弧焊接过程，采用等离子体光谱分析方法，观察了等离子弧焊过程中的放电形态，分析了金属蒸气对直流电弧焊和交流弧焊的影响，发现随着工作气体压力的升高，电弧电压和阳极热输入增加。工作气体种类对阳极热输入和电弧压力均有影响。认为阳极热输入和电弧压力共同控制着熔池中的金属蒸气现象。在交流弧焊中，焊缝金属的表面状态可分为白区和亮区两种类型。对于各种铝合金来说，阴极斑点从熔池延伸到清洁区。此外，不同铝合金的阴极光斑数目、半径和速度也不同。提出了铝合金的功函数和蒸气压共同控制熔池中金属蒸气的现象。

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.