常压等离子体弧清洗焊接预处理新方法

A New Method of Welding Pretreatment of Atmospheric Pressure Plasma Arc Cleaning

大气常压等离子体弧清洗是一种新颖的焊接预处理方法。针对预处理时厚度方向清洗界面移动、计算区域变化、边界条件非线性的难题,利用导热微分方程和阿伦尼乌斯定律,建立了大气常压等离子体弧清洗反应动力学模型并确定了频率因子、活化能等反应动力学参数,从而揭示了清洗百分比随清洗时间、金属零件表面氛围温度的变化规律,并进行了表面水滴接触角测量、X射线光电子能谱分析等相关实验验证。结果表明,大气常压等离子体弧可以快速清除表面污染物,有效实现焊接前的表面预处理。工件表面污染物的清洗百分比随大气常压等离子体弧清洗时间的增大而增大,直至该污染物被彻底清除;此外,清洗对象等离子体弧热流作用侧的表面氛围温度对清洗百分比有着重要影响,清洗百分比随氛围温度的增加而增加。

The atmosphere atmospheric plasma arc welding cleaning is a novel pretreatment method. According to the mobile cleaning interface, changeable calculation region and non-linear boundary conditions along the thickness direction,a mathematical model of reactive kinetics in the metal sulface contaminant cleaning using APPA has been developed, by means of thermal conduction differential equation and arrhenins equation. Afterwards, reactive kinetics parameters such as activation energy and pre-exponential factor are calculated. On this basis, the intrinsic relationship between contaminant removal percentages, removal rate and influencing factors such as cleaning time and ambient temperature of APPA cleaning are revealed and validated with related experiments results. The results indicate that contaminant removal percentages increase with cleaning time increasing until the contaminant is drastically cleaned by APPA. Furthermore, the ambient temperature of APPA on the contaminant suuface affects the removal percentages strongly. The removal percentages increase with the increase of the ambient temperature. To avoid the damage of metal substrate surface because of higher temperature and ensure the removal rate of the contaminant, the appropriate temperature which lies between the contaminant decomposition temperature and damage temperature of metal substrate.