Tribology design of micromachine surfaces using the modofication of Fullerene C_<60>

本研究的目的是开发超光滑富勒烯C_2<60>薄膜，以解决微机械的微摩擦学问题。为此，利用分子束外延（MBE）技术，用从努森池中升华出的C_2对二硫化钼（MoS_2）和高取向石墨（HOPG）表面进行了改<60>性。用<60>反射式高能电子衍射（RHEED）对分子束外延生长的C_2薄膜的生长和结构进行了原位分析，发现<60>C_2薄膜为密排外延生长，晶格常数为1.0nm。10个单层以上的厚膜也显示出具有面心立方结构的光滑表面。原子力显微镜（AFM）观察到厚C_2<60>膜具有三重对称畴结构，这与RHEED的结果一致，C_2膜的三重畴<60>结构是瑞士巴塞尔大学的研究小组和本研究首次发现的<60>。C膜具有超低摩擦力<60>。超过10个单层的厚膜也表现出低摩擦。MoS_2和HOPG基片的摩擦系数分别为0.019和0.012。这可能是由于分子束外延生长的C_2膜结构均匀、光滑所致。分子束外延生长的C_2膜对空气中的水分子具有疏水性<60>。这表明分子束外延生长的C_2膜在微机械领域具有良好的微摩擦学应用前景<60>。

The objective of this study was to develop ultrasmooth Fullerene C_<60> films for solving microtribological problems of micromachines. For this purpose, molecular beam epitaxy (MBE) has been used to modify molybdenum disulfide (MoS_2) and highly oriented pyrographite (HOPG) surfaces with C_<60> sublimated from the Knudsen cell. The growth and structure of MBE grown C_<60> have been analyzed in-situ with the reflection high energy electron diffraction (RHEED), and it was found that the C_<60> films show close-packed epitaxial growth with its lattice constant of 1.0nm. Thick film with more than 10 monolayrs also showed smooth surface having fcc structure. Atomic force microscopy (AFM) signified that thick C_<60> films have three-fold symmetry domain structure, which coincides with the results obtained by RHEED.The three-fold domain structure of C_<60> has only been made clear by the research group in Basel University, Switzerland and by this study.Microtribolgical properties of MBE grown C_<60> films have been conducted in an ordinary atmosphere using AFM and friction force microscopy (FFM). Ultralow friction was found for C_<60> films. Thick films with more than 10 monolayrs also showed low friction. Friction coefficients of 0.019 and 0.012 were found for MoS_2 and HOPG substrates, respectively. These values are much lower than those reported by the other three research groups, and this may be caused by the uniform and smooth film structure prepared by MBE.Hydrophobic property against water molecules contained in air was found for MBE grown C_<60> films. This strongly suggests microtribological applications of MBE grown C_<60> films to micromachine.