大面积工件自源自偏压空心阴极放电及用于高硬超厚DLC薄膜沉积研究

With the development of Industry, people pay more and more attention on precision and life of friction pairs. However there are still some problems on precision plasma surface treatment of large components using PVD/CVD techniques due to the shortage of proper plasma sources. SWRI in US invented large area DLC coating technique based on cage-mesh hollow cathode discharge with the components immersed. However its application is limited due to a lower hardness of deposited films. It is attributed to the shortage of ion bombardment. Thus we proposed an method with the components biased relative to the cage mesh. The experimental results have demonstrated that our idea is correct. However the manipulation of large components in the cage is relatively difficult. Finally we utilize a novel hollow cathode structure, in which the component is not in the cage. The component is set to be a part of hollow cathode and the cage is on the top of the component. The diodes are utilized to make the component and cage work together as hollow cathode and also make the component be biased relative to the cage. Consequently the ion bombardment effect is achieved and a novel technique is proposed for plasma surface modification for large area components based on self source/self bias hollow cathode discharge. Our preliminary results have demonstrated the feasibility of this technique. This project will focus on development of serial power supply with phase adjustment, effect of additional bias on hollow cathode discharge and effect of bias on microstructure and stress. All these are helpful for the deposition of harder and thicker DLC films for large components in industries.

随着工业发展，人们对摩擦副精度和寿命要求越来越高，但大型零部件（如大型模具）PVD/CVD精密等离子体表面处理因缺乏合适等离子体源一直很难解决。美国SWRI发明了一种将工件置于笼网中/空心阴极放电的大厚度DLC沉积方法。但膜层硬度低，应用受限，我们认为是膜层缺乏离子轰击造成，于是提出工件相对笼网施加偏压的方法。但在笼网内操作大工件很难，且放电不稳。为此我们摒弃原有空心阴极结构，工件不再放置笼网内，而是在外面做为空心阴极一部分，并巧妙利用二极管单向导通特性解决了工件“既要和笼网在一起构成空心阴极，又要与笼网分离相对笼网施加偏压”的矛盾，实现了膜层离子轰击效应，据此本项目提出一种大面积工件自源自偏压空心阴极放电新方法。前期试验证明了该方法可行性。课题研究包括相位可调串联电源研制，笼网空心阴极放电及附加电场影响，偏压对膜层结构和应力影响等，进而为工业应用大型零部件高硬超厚DLC沉积提供支撑。

针对笼形空心阴极制备的DLC薄膜缺少离子轰击，硬度较低的问题，本项目开发了一种相位可控脉冲高压电源（下称脉冲电源），实现了工件和笼网之间不等电势，为DLC膜层生长过程提供了有效的离子轰击，以此电源为基础提出了自源自偏压笼形空心阴极放电制备大面积DLC薄膜的方法，包括脉冲电源的设计、电源参数和笼网结构对空心阴极放电的影响、偏压幅值对DLC薄膜生长、结构及性能的影响、探索了提高大面积DLC薄膜均匀性的方法。.设计了相位可控的脉冲高压新型电源，利用电路仿真软件进行电路优化、电路安装与调试。将研制的新型电源嵌入到笼网空心阴极系统中，研究了笼网内大面积高密度等离子体放电特性。.增大笼网高度可以提高笼网发射电子的面积，促进空心阴极放电，在笼网高度为200 mm时放电电流最高，薄膜的沉积速率可达6μm/h。减小网眼大小会增加空心阴极放电电流。放电伏安曲线和光谱显示，施加偏压促进了乙炔（C2H2）和Ar/C2H2/ TMS混合气体放电强度。随着偏压的增加，Si-DLC薄膜的沉积速率和表面粗糙度先降低后增高，薄膜逐渐致密化，施加-200 V偏压的薄膜sp3含量较高，表现出较好的耐磨性、较低的摩擦系数和磨损率。 与不施加偏压相比，施加偏压制备薄膜的膜层厚度、硬度、耐磨性和均匀性等性能均得到提升。.利用大小笼网的组合实现了大面积、多点式Si-DLC薄膜的制备模式，可根据实际需求在不同表面制备DLC薄膜，有利于工业化应用。.通过本项目的资助，进行国际访问交流2次，作出大会报告及邀请报告15次，分会场报告1次。项目资助发表文章24篇，其中SCI论文16篇，EI 论文2篇，中文核心期刊论文6篇。申请发明专利 4 项目。举办高离化率磁控多弧应用技术研讨会3次（2017年、2018年、2019年）。