含氟聚氨酯大分子单体自组装薄膜的制备及摩擦性能

用己二酸和乙二醇在一定的条件下通过酯化和缩聚两步反应合成聚己二酸乙二醇酯（PEA）,测所得聚酯二元醇的酸酯（Av）和羟值（Qv）,得到合成聚氨酯大分子单体的原料.聚己二酸乙二醇酯（PEA）与等量的甲苯-2,4-二异氰酸酯（TDI-100）反应,加入十三氟-1-辛醇封端,得到含氟聚氨酯大分子单体（FPUOH）.利用分子自组装技术在玻璃基片表面制备含氟聚氨酯薄膜,对其进行结构表征和性能测试.亲水性测试结果表明,自组装薄膜与水的接触角为76.8°,证明了自组装薄膜制备的成功.微摩擦测试结果表明,含氟聚氨酯大分子自组装薄膜修饰的基底具有很好的减摩润滑效果,当载荷为400mN时,自组装薄膜的稳定摩擦系数达到0.09,适合作为轻载荷下的润滑防护保护膜.     

A New Process and Technology for Rapid Prototyping of A μ-Micro Motor

A new process and technology of rapid prototyping for a μ-micro motor is presented as a nontraditional machining and an advanced manufacturing technology (AMT) to be realized by using masks, including the operation principle of the motor, structure design, technique, driven circuit, and quality examination with Raman spectrum. The μ-micro motor is fabricated by the micro electro-mechanical systems (MEMS) process, the structure design must be considered to fabricate or assembly the parts during machining the motor in the meantime. The research proved that integration of IC (integrated circuit) process and MEMS using masks is effective in obtaining the rapid prototyping manufacturing of the μ-micro motor. With the mature technique to fabricate the motor, there are advantages to produce the motor in short time and with lower cost than before. The motor is a common power source of micro machines in military and civilian applications, for example, applied to micro robot, micro bio medicine, and micro machine. The size of the motor is 190 μm in maximum diameter by 125 μm in height that is bulk machined in array with the number of hundreds of micro motors on a substrate.     

基于Mo/SiO2布拉格声反射器的体声波谐振器的制备及其性能分析

采用射频反应磁控溅射法在p型(100)单晶硅衬底上交替沉积Mo/SiO2薄膜作为布拉格声学反射层,通过原子力显微镜(AFM)及扫描电子显微镜(SEM)分别表征声反射层薄膜的表面和截面形貌,研究溅射工艺条件对SiO2薄膜微观形貌的影响.采用MEMS工艺流程制备基于c轴择优取向AlN压电薄膜的SMR型谐振器.并对谐振器的S11参数进行测试分析,得到谐振器的中心频率为1.7 GHz,表明实验所制备的SMR型谐振器在质量传感方面具有一定的应用前景.     

射频分布式MEMS移相器Bragg频率的研究

详细讨论了Bragg频率产生的原因及其分析方法，并依据微波网络理论对不同结构参数MEMS移相器的Bragg频率进行了分析比较.计算结果表明Bragg频率随共平面波导信号线宽度增大、随微桥周期间距增大而降低.对特征阻抗50 Ω、周期间距300 μm、中心信号线宽度分别为50 μm和100 μm的MEMS移相器，Bragg频率相应为38.1 GHz和27.6 GHz；对中心信号线宽度为100 μm的移相器，当周期间距增加为567 μm时，Bragg频率进一步下降到19.6 GHz.对Bragg频率的研究为分布式MEMS移相器优化设计提供了重要依据.     

脉冲加热下微尺度表面流动沸腾

利用微机电系统(MEMS)加工技术,在梯形微通道内集成特定形状(60 μm×100 μm)的Pt微加热器,通过改变脉冲加热电压及水的流速,采用高速摄像机观察并记录微加热器表面的流动沸腾现象,根据脉冲宽度2 ms下不同流速及热流时微加热器表面的核态沸腾及膜态沸腾现象得到了沸腾流型图.结果表明：在一定流速条件下,随着微加热器的热流增加,核态沸腾及膜态沸腾相继出现在微加热器表面,且核态沸腾开始向膜态沸腾转变;同时,增加水的流速,可使微加热器上发生核态沸腾及膜态沸腾所需的热流量增大.     

稀土纳米膜的制备及摩擦学性能

在单晶硅和玻璃基片上用自组装的方法制备了稀土纳米膜,利用原子力显微镜(AFM)、接触角测量仪等测试手段对制备的薄膜进行了表征;并用自行研制的滑动往复式微摩擦测试系统测试了其摩擦特性.研究结果表明,在玻璃和单晶硅基片表面都成功地组装上了稀土自组装薄膜,未经表面改性的单晶硅和玻璃基片的摩擦系数分别为0.80和0.79,在其表面制备稀土纳米膜后的摩擦系数分别降低至0.16和0.11,同时耐磨性及摩擦稳定性都得到显著提高,显示了稀土纳米膜在微机构表面改性的潜在应用前景.     

纳米二氧化硅/硅异质结的表面光伏特性

采用溶胶 -凝胶法在P型单晶硅的表面镀上一层纳米二氧化硅薄膜 ,应用表面光电压谱 (SPS)、漫反射光谱 (DRS)和傅里叶红外光谱 (FTIR)研究其室温下的光伏、光吸收特性 .结果表明 :在单晶硅表面镀上一层纳米二氧化硅薄膜后 ,漫反射吸收系数F(R)比单晶硅提高了约 5 0 % ,相应的光电压信号提高了约两个数量级 .在 40 0～ 80 0℃热处理温度范围内随着温度的升高 ,纳米复合材料SiO2 /Si的光伏效应增强 ,红外光谱中的Si-O键振动吸收峰降低 ,二氧化硅薄膜中欠氧状态加剧 .     

可见光区三层减反射膜的设计

本文通过对可见光区减反射薄膜材料的选择和设计，采用计算机模拟，找出了在３５０～７５０ｎｍ范围内具有最好光谱中性的减反射膜系ＳｉＯ２ＴｉＯ２ＳｉＯ２玻璃基底，其结构为     

微机电系统微米间隙的预击穿和击穿特性研究

为了预测和评估微机电系统(MEMS)中微电极结构的绝缘性能,采用MEMS加工工艺,制备了电极间隙为5～40 μm的金属铝薄膜电极,研究了试样在直流电压下的预击穿过程中电流-电压关系曲线以及击穿电压随电极间隙的变化规律,并利用扫描电子显微镜(SEM)进行了微电极表面的微观分析.研究结果表明:预击穿过程的电流-电压曲线说明,在击穿之前电流的变化主要包括自由带电粒子的定向迁移阶段、电流密度达到饱和阶段以及碰撞电离持续发展形成电子雪崩阶段;场致电子发射的Fowler-Nordheim曲线表明,当微电极的间隙大于5 μm时,其击穿特性仍然符合巴申曲线,与相关文献的研究结论一致;微电极击穿阈值均大于相同间隙的宏观金属电极的击穿阈值;微电极击穿后在阳极表面有坑洞产生,而在阴极表面存在溅射沉积现象.     

Scale dependence of tensile strength of micromachined polysilicon MEMS structures due to microstructural and dimensional constraints

The success of microelectromechanical systems (MEMS) as a key technology in the 21st century depends in no small part on the solution of materials issues associated with the design and fabrication of complex MEMS devices. The reliable mechanical properties of these thin films are critical to the safety and functioning of these microdevices and should be accurately determined. In order to accomplish a reliable mechanical design of MEMS, a new microtensile test device using a magnetic-solenoid force actuator was developed to evaluate the mechanical properties of microfabricated polysilicon thin films with dimensions of 100—660 mm length, 20—200 mm width, and 2.4 mm thickness. It was found that the measured average value of Young抯 modulus, 164±1.2 GPa, falls within the theoretical bounds. The average fracture strength is 1.36 GPa with a standarddeviation of 0.14 GPa, and the Weibull modulus is 10.4—11.7, respectively. Statistical analysis of the specimen size effect on the tensile strength predicated the size effect on the length, the surface area and the volume of the specimens due tomicrostructural and dimensional constraints. The fracturestrength increases with the increase of the ratio of surfacearea to volume. In such cases the size effect can be tracedback to the ratio of surface area to volume as the governing parameter. The test data account for the uncertainties inmechanical properties and may be used in the future reliability design of polysilicon MEMS. The testing of 40specimens to failure results in a recommendation for design that the nominal strain be maintained below 0.0057.     

一种微型直接甲醇燃料电池的制作与测试

微型直接甲醇燃料电池(micro direct methanol fuel cell,μ-DMFC)具有发电效率高、环境污染少、安全、携带方便等优点,在小型民用电源和单兵携带电源上具有广泛的应用.讨论了微型直接甲醇燃料电池(micro direct methanol fuel cell,μ-DMFC)的特点,研究了运用微机电系统(micro-electro-mechanical systems,MEMS)工艺,设计并且制作μ-DMFC的过程.主要是运用MEMS 工艺制作μ-DMFC的流场板;制备膜电极(membrane electrode assembly,MEA);通过改进μ-DMFC的封装结构,采用聚二甲基硅氧烷(polydimethylsiloxane,PDMS)和金属夹具对μ-DMFC进行封装,有效地避免甲醇的渗漏;并且通过测试μ-DMFC的I-V特性,比较了不同封装结构下,μ-DMFC的电性能.实验结果表明,封装结构改进后的μ-DMFC,最大电流密度为14.82 mA/cm2,最大输出功率为0.661 mW.     

具有斜拉梁的串联接触式射频微机电系统开关

为解决悬臂梁结构的射频微机电系统开关在残余应力的作用下会发生翘曲的问题,提出在悬臂梁的顶端引入斜拉梁的方法。使用Al/Au复合桥膜作为射频微机电系统开关的上电极,实现了Au-Au接触,利用BorofloatTM玻璃作为衬底,使用电阻对导通状态下的射频信号与驱动电极旁路进行隔离,使它的射频性能不受驱动电压的影响。测试表明:隔离度在12 GHz的频率下,插入损耗和隔离度分别为-0.29 dB和-20 dB。该射频微机电系统开关适合于DC-X波段的应用。     

高强度激光三倍频增透膜的制备

激光技术的发展对增透膜的要求越来越高.采用溶胶-凝胶工艺,运用提拉法镀膜技术与氨处理的后处理工艺,制备了高强度的纳米多孔SiO2增透膜.利用分光光度计研究了提拉速度对透射光谱的影响.结果表明,可以通过控制提拉速度来控制薄透射峰值的位置.经过氨处理,薄膜的机械强度比未采用氨处理的薄膜大大增强,并利用红外光谱、原子力显微镜(AFM)等分析手段分析了薄膜强度增强的机理.最后在石英玻璃基底上镀制了激光三倍频增透膜,该薄膜在355nm处透射率为99.58％,满足了实际应用的需要.     

QK3玻璃基底上可见光区宽带增透膜研究

以QK3为基底设计了一种宽带可见光区增透膜（增透波长0．4-0．8μm）,工艺实现采用了电子束蒸发物理气相沉积的方法,薄膜材料仅含有TiO2和SiO2,并分别作为高低折射率材料。利用Edinburgh光谱仪对双面镀制该膜系样品的透过率进行测量,结果表明平均透过率达97．73％。环境测试表明,薄膜具有良好的稳定性和牢固度。该增透膜可以应用于可靠性要求较高的环境中。     

掺杂Co的介孔SiO_2的制备与表征

利用溶胶-凝胶法,在碱性条件下,以正硅酸乙酯和KH550(γ-氨丙基三乙氧基硅烷)为硅源,CTAB为模板制备掺杂Co的介孔SiO2,并用BET、XRD、FT-IR、XPS对所得介孔SiO2进行表征.结果表明:所得介孔SiO2上负载了钴纳米粒子,煅烧温度在400℃的样品的比表面积最大,当温度逐渐提高时所得样品比表面积反而减小;当n(SiO2)∶n(CTAB)为1∶0.20时,所得样品比表面积(514.2 m2.g-1)相对较高,所制备的样品呈双介孔结构.     

3-巯丙基三甲氧基硅烷自组装膜的制备及其摩擦学性能

采用分子自组装技术在羟基化的玻璃基片表面制备了3-巯丙基三甲氧基硅烷单层膜(MPTS-SAM),运用原子力显微镜(AFM)观察了薄膜的表面形貌,使用X射线光电子能谱仪(XPS)分析了薄膜表面典型元素的化学状态,并运用静-动摩擦系数测定仪评价了薄膜的摩擦磨损性能.研究结果表明:在组装初期,硅烷水解产物主要是与基体表面的羟基发生聚合反应,表面出现岛状物;随着组装时间的增加,基体表面的有机硅烷分子之间发生聚合反应,当组装90min后,可以在基体表面形成完整的自组装薄膜.当组装MPTE-SAM后,基片表面的摩擦系数由无膜时的0.85降到了0.19,说明MPTE-SAM可以降低基片的摩擦系数,并且在较低载荷下具有较好的耐磨性能.     

Silicon-rutile - an ultra-high pressure (UHP) mineral from an ophiolite

Silicon(Si)-rutile separated from the Luobusa podiform chromitite in the Yarlung Zangbo ophiolite of southern Tibet is typically about 50 μm×50 μm×200 μm in size and consists mainly of SiO2 and TiO2. The average mineral formula is (Ti0.82Si0.18)O2. Powder X-ray diffraction data show that it is tetragonal in form, and the unit cell dimensions and other parameters are: a=4.591(2)?, c=2.946(2)?, v=62.09(5)?3, c/a=0.6415, with a molar volume about 5% smaller than rutile (JCPDS, 21-1276). The Si4+ ions in silicon rutile are six-coordinated, and are substituted for Ti4+ in the rutile structural sites. The Si-rutile, along with other associated ultra-high minerals discovered in the chromitite, such as octahedral silicate, silicon-magnesium spinel (Si4+ ions are six-coordinated), diamond, and intergrown of SiO2 and FeO phases, probably originated from the transition zone or the lower mantle, and were brought to shallow levels beneath an oceanic spreading ridge by an upwelling superplume.     

Preparation and characterization of SiO2 non-catalytic nucleation coating for the solidification of undercooled melt

SiO2 non-catalytic nucleation films were coated onto a ceramic substrate and the inner surface of a ceramic crucible by the Sol-Gel method. The surface morphology of the coatings was characterized with an atomic force microscope and a scanning electronic microscope. The non-catalytic effect of the coating on the heterogeneous nucleation of metal melts was tested through measuring the nucleation undercooling. Investigation results indicated that the prepared coating could act as a baffle-wall to prevent the metal melt from nucleating heterogeneously on the inner surface of the crystalline crucible. The tiny holes with a diameter below 2 μm and heaves on the coating surface have no evident effect on the undercooling of metal melts. For a poly-layer coating, the super-layer can cover the cracks in the sub-layers, which prevents the cracks in the coating from spreading in the direction vertical to the coating layers and thus eliminates the effect of cracks on the coating.     

具有斜拉梁的串联接触式射频微机电系统开关

为解决悬臂梁结构的射频微机电系统开关在残余应力的作用下会发生翘曲的问题,提出在悬臂梁的顶端引入斜拉梁的方法。使用Al/Au复合桥膜作为射频微机电系统开关的上电极,实现了Au-Au接触,利用BorofloatTM玻璃作为衬底,使用电阻对导通状态下的射频信号与驱动电极旁路进行隔离,使它的射频性能不受驱动电压的影响。测试表明:隔离度在12GHz的频率下,插入损耗和隔离度分别为-0.29dB和-20dB。该射频微机电系统开关适合于DC-X波段的应用。     

Al2O3或TiO2掺杂的ScSZ固体电解质纳米晶薄膜的制备及表征

利用溶胶-凝胶旋涂法,在单晶硅基片(100)上分别制得了厚度约为0.31μm的(Al₂O₃)_0.10(Sc₂O₃)_0.08(ZrO2)_0.82和0.36μm的(Sc₂O₃)_0.125(TiO₂)_0.175(ZrO₂)_0.70固体电解质纳米晶薄膜。烧结实验结果表明,两种薄膜均在650℃以上开始晶化,温度越高,晶化越完全,在800℃可完全晶化;所得纳米晶颗粒呈纯的萤石结构立方相;铝和钛掺杂的纳米晶颗粒的平均大小分别为47和51nm。铝掺杂的薄膜非常均匀致密,然而,钛掺杂的薄膜存在少量微气孔。