由于尺度效应和表面效应的作用，MEMS涂层接触表面的黏着力和多尺度粗糙度成为影响其接触性能的重要因素。然而现有涂层接触模型没有同时考虑上述因素，难以合理解释MEMS涂层表面微/纳尺度下的接触行为。本项目拟开展如下研究：（1）考虑材料原子之间相互作用建立涂层单峰黏着接触模型，推导等效Tabor参数，研究由黏着引起的突跳现象及界面力和接触半径与表面分离距离的关系。（2）将上述单峰黏着接触模型与多尺度粗糙表面的分形几何表征耦合，建立多尺度粗糙表面的涂层黏着接触模型，获得黏着参数表达式，揭示多尺度粗糙度和层状材料特性对涂层黏着接触行为的影响。（3）采用原子力显微镜测量涂层表面形貌，由功率谱图获得分形参数，测量力-位移曲线，对多尺度粗糙表面黏着接触模型进行验证。（4）构建微/纳尺度黏着接触下涂层/基体界面的分层模型，阐释黏着作用对界面分层失效的影响机制。本研究将为MEMS涂层可靠性设计提供理论依据。

Because of the size effect and surface effect, the adhesive force and multi-scale roughness of coating surfaces for MEMS become the significant factors which influence the contact characteristics. However, these two factors have not been included simultaneously in the existing contact models for coatings, which were difficult to reasonably elucidate the contact behaviors at the micro and nano scales of coating surfaces for MEMS. This project intends to undertake the following studies. (1) An adhesive contact model of coatings at the asperity level will be established considering the molecular interaction inside the material, and an equivalent Tabor parameter will then be derived. Furthermore, the adhesion-induced snapping phenomenon and the formulae for the interfacial force and contact radius with the separation distance between surfaces will be studied. (2) An adhesive contact model of coatings with multi-scale rough surfaces will be developed by combining the fractal geometry characterization of multi-scale rough surfaces and the adhesive contact theory of coatings at a single asperity level. An expression for adhesion index will be derived and the influence of multi-scale roughness and layered material properities on the adhesive contact behaviors will be revealled. (3) The surface topography of coatings will be measured by the atomic force microscope, and the fractal parameters will be obtained from the power spectrum. Also, the force-displacement curve will be obtained from AFM experiment in order to validate the contact model of multi-scale rough surfaces. (4) The delamination model of the coating/substrate interface under adhesive contact at the micro and nano scales will be developed so that the influence of adhesion effect on the interfacial delamination will be illustrated. The objective of this project are to provide the key theoretical basis of reliably design for MEMS coatings.