High-rate Synthesis of Hybrid Coating Films by Plasma-Spraying Enhanced Chemical

本文介绍了利用弧光混合等离子体制备纳米结构的Ti-DLC薄膜。一种沉积装置，由直流等离子体炬、基片固定器和真空室组成。在火炬出口处安装直径为10 mm的小孔，可以在火炬和燃烧室之间产生压差。腔内用5,000 L/分钟的干泵进行抽真空。小孔和大型真空泵能使燃烧室内的压力保持在20-100帕，即使火炬内的压力为1个大气压。该焊枪采用钛空心阴极，通过弧光放电蒸发钛，然后用等离子射流喷涂到基板上。腔体内的压力低到足以产生缓慢放电。将13.56 MHz射频电源连接到衬底支架上，产生辉光放电等离子体并在衬底上添加负偏压，以C2H2和CH4为反应气体进行了Ti-DLC薄膜的沉积。典型的沉积条件是AS…直流电压和电流：13-15V，30-150A；手电筒用Ar：0.5-1.6 L/分钟；CH4和C2H2流量：0.02-1 L/分钟；射频功率：100-150W：负偏压：100-400V。扫描电子显微镜观察和能谱分析表明，薄膜中不仅含有纳米尺寸(即L-50 nm)的钛颗粒，而且在碳基质中还存在较大的液滴。根据拉曼光谱确定碳基质为类金刚石。采用涡流发生器减少液滴，发现在等离子体炬中加入C2H2和旋流中的Ar时，大部分液滴被消除。随着薄膜中钛含量从0降低到30体积%，薄膜的硬度从13 Gpa增加到30 GPa.在L镀膜时，膜层厚度约为5um，与不锈钢球的摩擦系数为0.3。弥散分布的纳米钛颗粒似乎降低了残余应力。这些结果表明，利用弧光混合等离子体CVD技术可以快速制备出较厚的Ti-DLC薄膜。较少

This study presents fabrication of nano-structured Ti-DLC films using are-glow hybrid plasma. A deposition apparatus consists of a DC plasma torch, a substrate holder and a vacuum chamber. An orifice of 10mm diameter mounted at the exit of the torch can generate pressure difference between the torch and the chamber. The chamber is evacuated by a dry pump of 5,000 L/min. The orifice and the large-scale vacuum pump enable to keep the pressure in chamber at 20-100 Pa, even if the pressure in the torch is 1 atm. The torch employs hollow cathode made of Ti, the Ti is evaporated by the arc discharge, and then sprayed onto the substrate with a plasma jet. The pressure in chamber is low enough to generate a slow discharge. The 13.56MHz RF power supply is connected to the substrate holder to generate a glow discharge plasma as well as to add a negative bias on the substrate.Deposition of Ti-DLC films were performed using C_2H_2 and CH_4 as the reactant gases. Typical deposition condition was as … More follows : DC voltage and current : 13-15 V,30-150 A ; Ar for torch : 0.5-1.6 L/min ; CH_4 and C_2H_2 flow rate : 0.02-1 L/min ; RF power : 100-150W : negative biasing voltage : 100-400V. SEM observation and EDAX analysis results suggest that the film includes not only nano-size (I.e. l-50nm) Ti particles but also large droplets in carbon matrix. The carbon matrix was assured as DLC according to Raman spectrascopy. The swirl now generator was adopted to reduce the droplets, it was found that most of droplets were eliminated when C_2H_2, was supplied into the plasma torch together with Ar in the swirl flow. The hardness of the deposited film increased from 13 to 30GPa with decreasing the Ti content in the film from 0 to 30 vol.%. The thickness of the film was approximately 5 um in l h deposition and the friction coefficient was 0.3 against stainless steel ball. The residual stress seems to be decreased by the dispersed Ti nano-particle. These results lead to the conclusion that thick Ti-DLC film can be fabricated at high growth rate by the arc-glow hybrid plasma CVD. Less