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

本文研究了利用发光杂化等离子体制备纳米结构Ti-DLC薄膜。一种沉积装置由直流等离子炬、衬底支架和真空室组成。在火炬出口处安装直径为10mm的孔口，可在火炬和燃烧室之间产生压力差。腔室由5000 L/min的干泵抽气。孔板和大型真空泵使腔内压力保持在20- 100pa，即使火炬中的压力为1atm。火炬采用钛空心阴极，钛通过电弧放电蒸发，然后用等离子体射流喷射到基材上。腔内压力低到足以产生缓慢的放电。13.56MHz射频电源连接到基板支架，以产生辉光放电等离子体，并在基板上添加负偏置。以C_2H_2和CH_4为反应物，制备Ti-DLC薄膜。典型沉积条件为：直流电压和电流：13-15 V，30-150 A；火炬氩气：0.5-1.6 L/min；CH_4和C_2H_2流量：0.02-1 L/min；射频功率：100-150W；负偏置电压：100-400V。SEM观察和EDAX分析结果表明，薄膜中不仅含有纳米尺寸（l-50nm）的Ti颗粒，还含有碳基体中的大液滴。根据拉曼光谱确定碳基体为DLC。采用旋流发生器减少液滴，发现在旋流中向等离子炬注入C_2H_2和Ar时，大部分液滴被消除。随着Ti含量从0 vol.%降低到30 vol.%，沉积膜的硬度从13 gpa提高到30GPa。在l h沉积时，膜厚约为5um，与不锈钢球的摩擦系数为0.3。分散的Ti纳米颗粒降低了残余应力。这些结果表明，采用电弧辉光混合等离子体CVD可以制备出高生长速率的Ti-DLC厚膜。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