微型机电系统（MEMS）是面向21世纪的关键技术，微型机械的设计与制造在很大程度上取决于材料问题的解决。影响微型机械装置功能和可靠性的薄膜材料力学性能需要精确的评价。利用电磁力驱动，设计了一种微拉伸装置，从而精确地测定了长度为100-660μm，宽度为20-200μm，厚度为2.4μm的多晶硅薄膜的力学性能。结果表明，测得的平均弹性模量为164 GPa±1.2 GPa，与理论计算值相当。平均拉伸强度为1.36 GPa±0.14 GPa，其威布尔分布参量为10.4-11.7。统计分析表明，由于微结构和尺寸的约束使得多晶硅薄膜的拉伸强度表现出对微构件长度、表面积和体积的尺寸效应。拉伸强度随表面积与体积之比值增加而增加，这一比值可作为尺寸效应的控制参量。测试数据解释了微构件力学性能参量的离散性，并可用于多晶硅微机械的可靠性设计。最后，提出了应变设计准则，允许应变为0.0057。

The increasing use of small micromechanical devices and advanced sensors has led to concern about the failure modes and reliability of these structures. The enormous promise will not materialize without substantial progress in overcoming the stiction, friction and wear associated with such devices and understanding the mechanical behavior of MEMS materials and structures. Self-assembled monolayers (SAMs) are release and anti-stiction coatings for MEMS. In this paper, the anti-stiction properties of octadecyltrichlorosilane (OTS) SAM were calculated. The microtribological properties of OTS SAM were investigated with a ball-on-flat microtribometer. The influence of OTS SAM on the mechanical properties of micromachined polysilicon films for MEMS was investigated with an accurate evaluation using the microtensile test device. It was concluded that the OTS SAM has good anti-stiction properties and low friction coefficients. The hydrophobic property of OTS is the main factor leading to an increase in the average fracture strength of micromachined polysilicon up to 32.46%. Thus, the operational stability and lifetime of MEMS can be raised when coated with self-assembled monolayers.

A new microtensile test device using a magnetic-solenoid force actuator was developed to evaluate the mechanical properties of microfabricated polysilicon thin films that were 100-660mm long, 20-200mm wide, and 2.4-mm thick. It was found that the measured average value of Young's modulus, 164 GPa

The nanoindentation fracture of multilayer hard coatings of TiNrTi C,N.rTiC, Al2O3rTiCrTi C,N.rTiC, TiNrTi C,N.rTiCrTi C,N.rTiC and TiNrTi C,N.rTiCrTi C,N.rTiCrTi C,N.rTiC, deposited on cemented carbide using a CVD technique was studied. Based on an analysis of the energy released in cracking, the calculated fracture toughness values of these coatings were 2.18, 1.74, 3.40 and 3.90 MPa m1r2, respectively. Both load-penetration depth and loadl penetration depth squared plots have been demonstrated to be necessary if a more complete understanding of the coating system behaviour is to be gained. The interfacial failure and the critical load of interfacial failure of these coatings were also discussed. A step was found in the forcel displacement curves at the onset of coating fracture. A straight line segment in the oad-penetration depth squared curves was discussed. The hardness, fracture toughness and anti-wearability of these coatings were compared. The results show that the fracture toughness and anti-wearability are getting higher with the layers increasing.

In the present study, high-Tc superconducting thin YBa2Cu3O7 films and polysilicon films were prepared to investigate the initial sliding friction properties using a ball-on-flat tribometer when samples were moved against a sapphire ball or a steel ball in ambient environment. The surface topography was measured with atomic force microscope (AFM). After five times testing, the experimental results indicate that the friction coefficient of YBa2Cu3O7 films is lower than that of polysilicon films when sliding against a sapphire ball and almost the same when sliding against a steel ball. In particular, the initial friction of YBa2Cu3O7 films is more stable when sliding against a sapphire ball. However, the initial friction of polysilicon films fluctuates during a cycle period when sliding against a sapphire ball. They are both stable when sliding against a steel ball. Although, the surface profile of the YBa2Cu3O7 film is rough and can be seen to be rougher than the polysilicon film, but the friction coefficient of the YBa2Cu3O7 film is lower than that of polysilicon film. Also, although the topography of YBa2Cu3O7 films changes during friction, the friction coefficients are stable. This clearly shows that the initial sliding friction of YBa2Cu3O7 films under microfriction is stable. The observation signifies YBCO film is a good film to prevent stick-slip motion in ambient environment. The wear properties of YBa2Cu3O7 films suggest that the superconducting outgrowths (CuO) are loose and they can be easily removed.