基于功能特性的MEMS表面结构三维测量评定探索

MEMS表面结构质量对其功能特性具有重要的影响,本文专门探索研究了MEMS表面结构三维测量评定,主要分析了其表面结构质量对其功能特性影响,并举例进行了分析;提出了基于功能特性的MEMS表面结构三维测量评定综合参数、测量评定流程方案.     

机械零件织构化表面减摩性能研究进展

表面织构作为一种新兴的表面技术，良好的减摩效果引起国内外学者的广泛关注，现已被大量应用于工程领域。然而织构化表面的减摩效果受众多因素影响，不同工况因其特有的属性，表面减摩机制亦各不相同，对织构化表面提升材料的减摩耐磨机制尚不明确。从不同工况下织构的减摩性能出发，探究其减摩机制的异同并分析其原因，归纳不同类型织构的减摩理论及存在的问题；对当下织构加工方式优劣进行分析，并对织构技术未来的发展趋势进行展望和预测。     

载能电刀仿生防粘表面技术

微创手术具有创伤小、疼痛轻、恢复快等优点已逐渐成为外科手术主流。微创手术组织的切割、止血常采用载能手术器械如电刀、电凝钩来完成,组织粘刀严重,会引起结痂、粘刀撕裂,造成二次创伤引起医疗事故。如何解决载能手术刀粘刀是微创手术器械面临的重要技术难题,本研究师法自然,从自然中汲取表面超滑防粘创新灵感,在揭示猪笼草湿滑防粘机制的基础上,提出液膜式防粘新策略,研究了仿生防粘表面结构高温防粘机理以及制备工艺方法。通过软组织载能切削试验测试了仿生防粘表面防粘性能、以及组织热损伤与耐久性,试验结果证实了仿生防粘表面的防粘效果得到显著提升,组织粘附力降低80%、组织粘附量降低88%、创口损伤面积减小82.6%、热损伤面积减小71%,满足了载能微创手术器械防粘技术要求。     

加成型硅胶基防粘涂层性能研究

本文以加成型硅胶基材料为主要成膜物质,通过添加一定量的POSS和纳米SiO_2降低涂层的表面张力,得到具有防粘性能的涂层。研究了涂层的接触角、表面粗糙度和表面防粘性能,得出当POSS质量含量为3%时,接触角为92.9°,表面粗糙度值为25.2nm,此时涂层表面的防粘力达到一个较低值。随着聚氨酯胶带与涂层表面接触时间的延长,涂层表面的防粘力呈逐渐增大的趋势。     

复合润滑结构表面在油润滑下的减摩性能*

为研究不同表面处理方式对巴氏合金/45钢配副表面减摩性能的影响,采用热压固化工艺将六方氮化硼封装于表面织构内,制备复合润滑结构表面;在油润滑下进行销-盘磨损试验,使用递归定量分析（Recurrence quantification analysis,RQA）参数划分磨损过程;研究复合润滑结构表面在磨合期和正常磨损期的减摩性能,并与纯织构表面减摩性能进行对比。结果表明：复合润滑结构表面拥有较低摩擦因数和显著减摩效果,其减摩性能优于纯织构表面;相比无织构表面,复合润滑结构表面在磨合期内的平均摩擦因数下降77.9%,在正常磨损期内的平均摩擦因数下降73.5%且磨合期的时长缩减75.0%;较大织构孔径的复合润滑结构表面的减摩效果更好且磨合期更短;纯织构和复合润滑结构表面的减摩效果均在较高速度和载荷下更显著;各试样表面在磨合期的摩擦因数越低,对应进入正常磨损期后就越低。     

超声振动减摩性能的实验研究及理论分析

以超声减摩的核心构件压电振子为研究对象，在测量压电振子参数的基础上通过改变压电振子的工作电压，测量压电振子振动时辐射端面与特定的工作表面间的摩擦系数的变化规律，通过有限元法计算压电振子的振动模态，分析超声振动的减摩机理，以便进行适当的结构设计，利用超声振动的减摩性能制造出超声波悬浮轴承。研究证明，超声振动具有良好的减摩性能，压电振子处于纵向振动模态时减摩效果最好。     

超细蛇纹石粉体的材料特性、摩擦学介入行为及其工业应用

采用X射线衍射分析(XRD)、差热分析(DTA)、氮吸附-脱附(Nitrogen adsorption-desorption)等方法测试超细蛇纹石粉体在物理形态、表面特征、晶体结构、热反应和相变等方面的材料特性。初步分析其之所以能成为减摩修复剂主要功能组分的材料学基础。采用扫描电子显微镜(SEM)和纳米压痕法(Nano-indentation)等手段对摩擦磨损试验的试件进行摩擦因数、表面形貌和表面硬度的观测,证实在润滑油中介入以这种粉体为主的功能材料可使摩擦表面改性,继而提高表面摩擦学性能。而以超细蛇纹石粉体为主要原料的金属减摩修复剂在铁路内燃机车柴油机应用的初步成效,则从生产实践上证明这种功能物质介入摩擦副的有效性和它的实用价值。     

几种极压抗磨剂对Si3 N4陶瓷/GCr15钢副摩擦磨损性能的影响

利用MPX-2000型盘销式摩擦磨损试验机对Si3N4陶瓷与GCr15钢摩擦副在P120、T302、T306、T307、T321 5种极压抗磨添加剂作用下的摩擦磨损性能；采用SHIMADZU SSX-550型扫描电子显微镜观察盘试件的磨损表面形貌。结果表明：5种添加剂对该摩擦副均具有较明显的减摩抗磨作用，但是添加剂对该摩擦副的减摩和抗磨作用效果并不同步，P120的抗磨作用最好，T321的减摩效果最佳；综合考虑减摩抗磨时，添加剂P120的作用效果最佳；添加剂主要是通过物理和化学吸附膜对该摩擦副起到减摩抗磨作用；从SEM照片看，盘试件磨损表面主要表现为擦伤和粘着特征。     

MEMS中的摩擦学研究及发展趋势

对近年国内外MEMS摩擦学研究的新进展作了综述，介绍了MEMS系统的纳米摩擦学特性，讨论了包括环境条件、材料处理、表面改性、固体薄膜润滑、分子超薄膜润滑等在解决MEMS摩擦和润滑问题上的研究状况，并提出了当前相关研究中所遇到的问题，及今后MEMS摩擦学发展的方向。     

高载荷条件下的材料表面摩擦因数测量

针对材料表面高载荷条件的要求，提出了测量摩擦因数的方法，并进行了相应测试装置的设计，该测试装置由正向加载装置、侧向加载装置和数据处理装置3部分组成。可以用来测量高载荷条件下材料表面的静摩擦因数和滑动摩擦因数，同时得到整个滑动过程中摩擦因数变化情况。利用该装置对某国防减摩涂层进行了测试，结果表明在高载荷条件下该涂层对碳钢表面具有较好的减摩效果。     

Fe3Al基复合材料摩擦表面的分形特性研究

利用结构函数法对Fe3A l基复合材料干滑动摩擦表面的分形特性进行了研究,并计算其分形维数。结果表明Fe3A l基复合材料摩擦表面具有明显的分形特征,分形维数和摩擦因数以及磨损率之间有着密切相关性,随着分形维数的增大,摩擦因数和磨损率都逐渐减小,磨损率尤为明显,说明材料摩擦表面形貌特征对其摩擦学性能具有显著影响。     

基于分形理论的柱塞泵/马达配流副润滑特性研究

为研究配流盘表面形貌对配流副润滑特性的影响,采用分形理论模拟配流盘表面形貌,建立轴向柱塞泵配流副润滑模型,使用有限差分法对模型进行求解,探讨分形参数对表面轮廓的影响,并进一步分析分形参数和配流副工况参数对油膜承载力、摩擦力、摩擦转矩和摩擦因数的影响。结果表明：分形维数越大,表面轮廓形貌复杂度越高,且粗糙表面高度随尺度系数减小而降低;随着缸体倾角和转速的增大,油膜承载力提升,但摩擦力、摩擦转矩和摩擦因数也随之升高;配流副润滑性能与分形维数呈现正相关的关系,选取较大的分形维数有利于提升配流副的润滑性能;尺度系数越小其摩擦力越小,但承载力也减小,因此需选择适中的尺度系数。     

Si_3N_4陶瓷旋转超声磨削加工的表面摩擦特性

为了探索结构陶瓷材料在摩擦过程中表面形貌的变化规律及其对摩擦特性影响,分析了摩擦过程中材料的接触过程及力学关系,并对旋转超声磨削加工的Si3N4陶瓷试样开展了摩擦表面形貌、摩擦因数等特性的试验研究。首先根据接触特点和材料特性,基于分形理论推导出接触面总载荷计算公式,基于该公式建立了结构陶瓷摩擦因数分形模型。分析结果表明:当初始表面轮廓分形维数分别为1.4,1.45,1.5和1.55时,摩擦因数与摩擦后表面轮廓分形维数呈类似正态分布曲线。然后通过旋转超声磨削加工的Si3N4陶瓷试样面面接触摩擦试验,研究了摩擦后陶瓷材料表面微观形貌和摩擦因数变化规律,分析了各因素对摩擦因数的影响。试验结果表明:产生微观裂纹是Si3N4陶瓷摩擦后表面微观形貌的显著特点;温度值等于160℃是Si3N4陶瓷摩擦因数由下降转为上升的拐点;当施加载荷为360N和往复频率为80Hz时,摩擦因数最大。得到的结果为通过表面形貌控制提高结构陶瓷耐磨性能提供了技术支撑。     

超声电机定子和转子接触微观表面分析和形貌模拟

研究了行波超声电机定、转子接触表面的摩擦特性,测试了摩擦副表面的粗糙度、功率谱函数和分形维,利用分形几何模拟了摩擦层表面的表面形貌.研究表明,摩擦材料层表面特性对电机的运行特性的影响不能忽视;相对于摩擦材料铜表面是光滑的.研究有助于分析超声电机定、转子接触表面的微观力学特性,建立超声电机的接触模型.     

Microdevice for measuring friction and adhesion properties of sidewall contact interfaces of microelectromechanical systems

A microdevice was specifically designed to characterize the static and dynamic friction and adhesion characteristics of sidewall contact interfaces of microelectromechanical systems (MEMS). The microdevice was fabricated by surface micromachining and tested under conditions that accurately mimic those of typical MEMS contacts. The developed experimental scheme enables the direct measurement of the critical normal force at the instant of surface separation and the friction force at the onset of sliding. Additional capabilities include evaluation of the dynamic friction behavior, measurement of the electrical characteristics across the contact interface, and characterization of the tribological response under impact contact loading. The microdevice can operate over a wide range of normal forces and different environmental conditions. Because the design is independent of process environment, the microdevice can be used to study the effects of different surface treatments and variations in fabrication process steps on the tribological properties of MEMS contact interfaces. Characteristic results of static and dynamic friction behaviors, electrical contact resistance, and response to dynamic impact loading illustrate the experimental capabilities and versatility of the designed microdevice.     

基于分形接触的静摩擦系数预测

根据Ｍ－Ｂ分形接触模型对静摩擦系数进行预测。对分形参数Ｄ、Ｇ及材料参数φ对静摩擦系数的影响进行研究。结果表明静摩擦系数随载荷的增加而增加。这与在极低载荷下静摩擦系数很小的试验事实吻合,因此,Ｍ－Ｂ分形接触模型可能仅适用于载荷极小的情况。     

Friction Modifier Behaviour in Lubricated MEMS Devices

Low viscosity fluids could provide reliable lubrication for certain microelectromechanical system’s (MEMS) applications where high-sliding speeds and/or high sliding distances occur. However, while the use of low viscosity fluids leads to reduced hydrodynamic friction, high boundary friction can be a significant issue at low entrainment speeds. This article describes a series of tests of low viscosity fluids, blended with a friction modifier additive so as to provide a combination of both low hydrodynamic and low boundary friction at MEMS scales. The low viscosity fluids tested were hexadecane, low viscosity silicone oil, toluene and water. With the exception of water, the addition of the organic friction modifier octadecylamine to all these lubricating fluids produced a significant reduction in boundary friction. For a MEMS contact lubricated with silicone oil for instance, boundary friction was reduced from 0.5 to close to 0.05. The presence of the amine dissolved in the toluene had the effect of reducing boundary friction from 0.75 to 0.55; this was further reduced to 0.25 after the specimens had been immersed in the toluene-additive blend for 48 h. A water-soluble additive, diethylamine, was added to de-ionized water, at 0.1% by weight concentration. Although an initial reduction in boundary friction was observed (0.45–0.25), under these conditions the rapid onset of severe wear negated these effects. It is suggested that corrosion of silicon by water, followed by abrasion, is the cause of this accelerated wear.     

Molecular lubricants for silicon‐based microelectromechanical systems (MEMS): a novel assembly strategy

Microelectromechanical systems (MEMS) are poised to bring the next technology revolution. At present, many of these are fabricated from silicon using lithographic techniques developed in the microelectronics industry. Due to the large surface area to volume ratio on the micrometer scale, surface forces, such as adhesion and friction, are often detrimental to the fabrication and operation of MEMS devices. Thus, one of the key issues in MEMS is surface engineering to reduce adhesion and friction. Here, we present a general strategy for the efficient assembly of organic layers directly onto the silicon surface in both vacuum environment and solution phases via the robust Si–N or Si–O linkage. This is achieved by the reaction between an amine or alcohol functional group and a chlorinated Si surface. The resulting surface assemblies are thermally stable. Characterization by interfacial force microscope (IFM) reveals that these assemblies have very low surface energy and are mechanically stable. This revised version was published online in September 2006 with corrections to the Cover Date.     

In situ wear studies of surface micromachined interfaces subject to controlled loading

Friction and wear are major limiting factors for the development and commercial implementation of devices fabricated by surface micromachining techniques. These tribological properties are studied using a polycrystalline silicon nanotractor device, which provides abundant, quantitative information about friction and wear at an actual microelectromechanical system (MEMS) interface. This in situ approach to measuring tribological properties of MEMS, combined with high-resolution atomic force microscope (AFM) images of wear tracks, provides insight into the effects of different MEMS surface processing on wear. In particular, monolayer coatings have a significant positive effect, while surface texturing does not strongly affect performance.