直流电弧喷射等离子体炬阳极喷嘴积碳现象的研究

Study on Carbon Balls in Anode Nozzle of DC Arc Jet Plasma Torch

采用高功率直流电弧等离子体喷射化学气相沉积工艺,制备了不同厚度的自支称金刚石厚膜。实验发现,等离子体炬阳极喷嘴积碳是沉积过程中最突出的问题之一。从理论和实验两个方面研究了阳极积碳产生的原因,并通过激光拉曼光谱分析了碳球的结构和成分。结果表明,碳球由金刚石层、混合层和最外面的石墨层构成。详细分析了甲烷浓度、冷却水温度、放电电弧的局部高温、阳极喷嘴的表面质量对积碳形成的影响,并提出了改进措施。

The free-standing diamond film wafers with different thickness were prepared by high power DC arc plasma jet CVD method. The question of carbon balls in anode nozzle was one of the most serious problems during the deposition. The reasons were firstly studied with theoretical analysis and experimental investigation. Structures and compositions of the carbon balls were examined by Raman spectra. The results indicated that carbon balls were consisted of three layers, which were diamond film, mixed layer and outermost graphite. Effect on the formation of carbon balls was studied in detail by methane concentration, temperature of cooling water, local high temperature of discharge arc, surface finish of anode nozzle. The ways to solve this problem are presented.