超薄ta-C碳膜的双弯曲磁过滤阴极电弧制备与摩擦润滑机制研究

Ultrathin tetrahedral amorphous carbon (ta-C) films, owning high hardness, good wear and corrosion resistance properties, are considered to be the best candidate as protective and lubricant coatings to meet the increasing demands of ultrahigh density and capacity data storage devices and MEMS components. Currently, magnetic filtering cathodic vacuum arc (FCVA) deposition technique is the most promising one due to its high ionization and high density plasmas, however, the co-deposited macro-particles is the key barrier to obtain ultrathin ta-C films with high performance. In this project, we focus on the study of deposition, characterization and friction behavior of the ultrathin ta-C films by a hybrid homemade deposition system, which is composed of a novel developed 45º double bent FCVA source and a DC magnetron sputtering source. Specifically, the influence of key deposition parameters (ion kinetic energy, density, distribution of plasmas and so on) on the evolution of kinetic growth, sp3/sp2 atomic bonds, and microstructure of ultrathin ta-C films are investigated systematically. Meanwhile, the mechanical and tribological properties of films are studied as well. Most importanly, molecule dynamics simulation (MD) from atomic scale viewpoint is employed to reveal the kinetic motion behaviors of deposited particles in the surface and interface region. Based on the experimental and calculation results, we aim to clarify the deposition mechanism and low friction lubrication mechanism of ultrathin ta-C films, to develop the novel synthesis techinque for ultrathin ta-C films with superhigh hardness, supersmooth surface, low friction coefficient and good wear resistance, to establish a novel non-destructive, fast, accurate ellipsometry characterizition method for carbon atomic bonds, and to provide the theroretical and experimental basis for designing and preparation ultrathin ta-C films with high performance to meet the lubricant coating demands of MEMS,data storage,and related components.

具有超薄、超光滑、超硬、良好耐磨性的四面体非晶碳膜(ta-C)是目前获得超高密度、大容量数据存储器和高可靠、低摩擦、长寿命运行微电子机械系统金属部件用关键润滑防护改性材料。磁过滤阴极电弧技术是制备ta-C碳膜的主要方法，然而由于石墨阴极弧斑不规则放电机理，大颗粒协同沉积污染严重，薄膜质量差。本项目采用自主研制的45度双弯曲磁过滤阴极电弧复合技术，设计制备超薄ta-C碳膜，改变沉积参数实现薄膜微结构和性能调控，通过对薄膜动力学生长、微结构、力学和摩擦学物性的演变规律研究，结合分子动力学模拟计算，旨在阐明超薄ta-C膜的生长机制及摩擦润滑机理，建立获得超硬、超光滑、低摩擦的高质量超薄ta-C膜可控制备方法，同时发展一种无损、快速、准确测量超薄ta-C碳键态结构与含量（sp3/sp2）的椭偏表征新方法，为研究发展金属表面改性用高性能碳膜材料的设计、制备、表征提供理论依据和方法。

针对金属表面改性技术领域中对高性能润滑防护ta-C材料的重大需求，以及超薄 ta-C膜生长机制和润滑机理不明确的关键科学问题，本项目通过分子动力学模拟和实验研究了ta-C薄膜的生长行为及应力特性；研究并发展了ta-C薄膜的椭偏与分光光度计联用表征方法；进一步采用自主研制的45°双弯曲磁过滤阴极电弧沉积系统，调控弧流、刻蚀工艺、负偏压等参数实现了ta-C薄膜的可控制备；建立了薄膜微结构与机械性能、摩擦性能的作用规律。主要结果概括如下：.1、结合分子动力学模拟与实验，阐明了超薄ta-C薄膜的生长模式与应力演变规律。发现随碳源入射角由0°增加到60°，畸变键长键角数目减少；当入射角为60°时，因无序的C-C键长和键角协同弛豫导致应力大幅降低，但因薄膜中sp3含量不变导致力学性能保持良好，这为高性能ta-C薄膜制备提供了新思路。.2、针对传统EELS、椭偏、Raman等方法在精确测量碳结构和膜厚等方面存在不足，创新发展椭偏联用分光光度计法，这不仅解决了ta-C薄膜键态含量和膜厚精确表征的难题，且为其他吸收薄膜的有关膜厚和光学参数精确测量提供了新途径。.3、调控工艺参数，实现了ta-C薄膜的设计与制备。通过电弧刻蚀技术结合弧流、偏压的优化调控，发现高密度的Ar+离子轰击有助于少量C+离子的预沉积，基体和薄膜间构筑了a-C/ta-C的梯度结构，从而实现强膜基结合突破。同时，采用高通量研发思路，获得了膜厚在4.7 nm到183 nm的ta-C薄膜在直径为7 cm范围的均匀、致密、光滑高质量制备。.4、揭示了ta-C薄膜的宏观和微纳摩擦相关机理。宏观摩擦发现随载荷增加，ta-C薄膜摩擦系数降低，磨损率增加，主要源于转移膜石墨化程度增加降低摩擦系数，但界面处铁的氧化物存在造成磨粒磨损加剧失效。微纳摩擦则发现超薄ta-C的摩擦力都随垂直载荷的增加而增大，大致呈线性关系，且满足修正的Amonton摩擦定律：Ff =Fadh +μFN，说明微纳尺度摩擦主要由表面粘附力主导，不饱和悬挂键含量是决定因素。.本项目发表论文8篇、专利4件、专著2部，国内外特邀报告6次，出访和来访交流30余人次。