激光频率对激光溅射法制备多晶硅薄膜压阻特性的研究

采用脉冲激光溅射法制备硼掺杂多晶硅薄膜,研究了不同频率下多晶硅薄膜的晶粒尺寸以及压阻性能。用扫描电子显微镜表征在不同的激光频率沉积的多晶硅薄膜的表面形貌,以及悬臂梁实验测定在不同的激光频率下沉积的多晶硅薄膜的应变系数。结果表明溅射频率对激光溅射法制备的硼掺杂多晶硅薄膜的晶粒尺寸和压阻性能都有着明显的影响,当频率为3 Hz时多晶硅薄膜的晶粒尺寸较大,约为35~65μm,并且多晶硅薄膜有着良好的压阻性能,其应变系数为36.8,电阻的温度系数为-0.036%/℃,应变系数的温度系数为-0.09%/℃。     

脉冲激光沉积磷掺杂多晶硅薄膜的压阻性能

采用脉冲激光沉积法(PLD)制备磷掺杂多晶硅薄膜,研究磷掺杂分数对多晶硅薄膜压阻性能的影响。结果表明,随着磷掺杂分数增大,多晶硅薄膜的应变系数先增大后减小。在磷掺杂分数为0.3%(质量分数)时,电阻横向应变系数的绝对值达到最大,为24.3,电阻纵向应变系数的绝对值达到最大,为12.6。横向电阻应变的非线性在1%~2.5%之间,电阻的温度系数为0.05%/℃,应变系数的温度系数为-0.06%/℃。     

应变电测与传感器技术的新发展及应用

首先介绍应变电测与传感器技术的新发展:(1)各种新型特殊电阻应变计:高温600～800℃密封焊接式应变计,900℃粘贴式动态应变计,低温-269～-196℃电阻应变计,防水应变计,大应变15%～30%电阻应变计等。(2)新型应变计式传感器:土木、机械用力传感器,钢筋计,土压力计,扭矩传感器,六分力传感器,另有应变传感器可安装在结构上测量应变,可重复使用,配合应变测试仪器使用,还可进行无线遥测。(3)新型数据采集仪器:高速静态数据采集仪,最多达1000通道,可测应变、温度、应变式传感器、直流电压等,精度0.05%,采集速度每通道0.04s,多通道总计0.4s采集完成;小型多通道动态应变和温度记录仪,最多有80通道,其中应变最多达64通道,其余为热电偶、电压测量通道;超动态电阻应变仪,频响可达200～500kHz,另有数据采集和分析软件可快速分析处理数据。其次介绍近来在土木工程、铁路工程、机械工程和航空航天工程以及医学、体育等领域中的若干应用实例。     

高温灵敏系数标定影响因素分析

高温应变计是高温结构强度测试、疲劳测试和寿命评估的主要测量传感器,其灵敏系数测试的准确性影响高温应变测试中应变修正数据的真实性。对应变计灵敏系数原理进行分析,明确灵敏系数是应变计输出与应变之间的关系,对砝码加载四点式简支梁结构和纯弯矩钢架梁结构灵敏系数测量模型进行分析,确定产生标准应变的影响因素。常温灵敏系数标定的影响因素有试验梁尺寸、试验梁轴向力,实际灵敏系数测试结果表明简支梁灵敏系数略大,分散明显较大。高温下应变计的输出与载荷应变、应变计热输出、试验梁尺寸变化、弹性模量变化和摩擦力变化有关,对热输出消除方法进行探讨,理论上明确温度下简支梁尺寸变化、弹性模量变化误差高达22%,钢架梁的刚性封闭静态力学平衡系统的温度影响误差较小。利用自研框架式高温裸栅应变计、高温陶瓷胶,进一步用简支梁、钢架梁实际测试灵敏系数随温度变化验证了理论分析的正确性。     

用应变计在低温下测量应变和位移

在低温下测量应变和位移，电阻应变计测量系统以其精度和易操作而特别著名，在低温条件下测量时，重要的是要掌握应变计的基本性能，例如，视应变和应变灵敏系数与温度的关系，研究位移测量时有多种应变计装置，粗略可分为棒式和夹式丙类，以满足不同的测量目的，其主要性能决于所用的应变计，各个领域的位移测量。采用应变计显然是有益的。     

测定碳复合材料高温力学性能的高温电阻应变计

根据应用于航空、航天等重要工程的新型碳复合材料研制的需要,我们近年来开展了测定碳复合材料高温力学性能用的高温电阻应变计及其粘结剂的研究工作.首先我们采用现有4107胶制400℃粘贴式应变计对碳/陶瓷复合材料测定了400℃应力-应变性能,在粘结强度和传递应变能力方面都得到了较好的效果.然后,我们主要研制了新型高温应变测定550℃下碳/陶瓷复合材料力学性能,其关键是研制适用于碳复合材料的高温粘结剂.      

750℃高温电阻应变计的研究与应用

本文介绍了笔者近年来研制成功的几种新型应变计及其应用技术,以及应变计热输出、零点漂移、输出变化率等温度特性对高温应变测量的影响,以及Fe-Cr-Al应变合金的氧化和相变对应变计温度特性的影响。着重指出Fe-Cr-Al的温度自补偿的范围是有限的,期望通过热处理实现全范围温度自补偿的目的,还难于达到,而且可能产生较大的,难以估量的测量误差。在此基础上总结了对提高测量精度很有益的一些基本规律。     

浅析称重传感器的温度自补偿

1 电阻应变计的温度自补偿。对电阻应变计的温度效应来说,主要由两个因素引起,一个是应变合金丝（或箔）材料的电阻随温度变化而变化,另一个是传感器弹性体和应变合金丝（或箔）材料线膨胀系数不同引起的附加变形,使应变计电阻也产生了相应的变化.如果不考虑粘合剂的影响,当温度变化△t时,设应变计电阻丝栅电阻的改变量为△R1,则△R1=Rα△t（1）式中：R为应变计电阻;α为应变合金丝栅的电阻温度系数.     

空间太阳电池玻璃盖板表面超薄ITO防静电层的设计及制备工艺

ITO/MgF2复合薄膜既具有较好的表面导电性能又具有较高的透过率,可应用于空间太阳电池玻璃盖板表面。文章主要对ITO/MgF2复合薄膜中表层的超薄ITO薄膜进行了研究。利用TFCalc软件模拟了ITO薄膜厚度对ITO/MgF2复合薄膜光学性能的影响,根据模拟结果采用电子束蒸发法在衬底上依次沉积MgF2薄膜和氧化铟锡(ITO)薄膜,研究了ITO薄膜工艺参数(沉积速率、沉积温度和工作气压)和ITO薄膜厚度对ITO/MgF2复合薄膜光电性能及微观结构的影响。当ITO薄膜沉积速率为0.05nm/s、沉积温度为400℃、工作气压为2.3×10~(-2) Pa、厚度为10nm时,表层ITO薄膜基本连续,其方块电阻(1.94kΩ/)已符合设计需求,ITO/MgF2复合薄膜在可见光区间(400~800nm)的平均透过率达到89.00%。     

溶胶-凝胶法制备的ITO薄膜电学及光学性能的研究

以无机盐为出发原料．采用溶胶-凝胶法制备了氧化铟锡(ITO)透明导电薄膜。进一步研究了热处理气氛、温度、Sn掺杂量时In2O3薄膜电学及光学性能的影响。分别在氮气、真空和空气3种环境下对薄膜进行热处理．结果表明真空热处理后薄膜的导电性最好。研究了薄膜方块电阻随锡掺杂量的变化．发现薄膜的方阻随掺锡量的增加先减小后增加,并在掺杂量为7mol％左右时达到最低;另外探讨了热处理温度对薄膜光电性能的影响．结果发现薄膜方块电阻随热处理温度的升高而减小．且热处理温度高于700℃后变化不显著,薄膜在可见光区平均透过率随热处理温度升高呈上升趋势。本研究所制得的薄膜可见光区(400-800nm)平均透过率可达85％、方阻约为66Ω。     

Temperature-Independent Conductive Ceramic for High-Temperature Strain-Sensing Applications

Temperature-independent properties are critical for high-temperature thin-film strain gauges (TFSGs). In this study, by controlling the electron scattering and tunneling effects in the TiB₂/SiCN composites, the environmental interference of temperature fluctuations is successfully eliminated, and a temperature-independent TFSG is fabricated. The effects of pyrolysis temperature and TiB₂ content on the microstructural evolution and electrical properties of the ceramic films are studied. The temperature insensitivity is mainly attributed to the balance between the intrasheet resistance with a positive temperature coefficient of resistance (TCR) and the intersheet resistance with a negative TCR. This composite shows nearly constant resistance values over an ultrawide temperature range of 300–700 °C, with less than 0.05% deviation of the normalized resistance and TCR values as low as 1.6 ppm °C⁻¹. In addition, the TiB₂/SiCN films exhibited stable piezoresistive responses, with a gauge factor of 4.28, and the temperature-independent strain response in the high-temperature range is verified.     

Höchste Präzision in kurzer Taktzeit

Highest precision in short cycle time – highly sensitive thin fiim strain gauges produced in an industrial high‐rate‐sputtering system Commonly, sputtered strain gauges are already used for highly precise pressure sensors. By using special highly sensitive piezoresistive nanocomposites consisting of metal nanoparticles embedded in an insulating matrix made from diamond‐like carbon (DLC) the sensitivity to strain can be significantly increased. Essential parameters for the characterization of the thin films used as sensor layer are the strain sensitivity (described by the gauge factor) and the temperature coefficient of resistance (TCR). Conventionally used NiCr alloys have a gauge factor of approximately 2. By using metal‐DLC nanocomposite films a factor 5 to 10 higher strain sensitivity in combination with a TCR close to zero was reached on laboratory scale. At first, the highly sensitive films were produced by static deposition using a box coater which led to quite long process times. By using a dynamic deposition process in the same machine the throughput of samples was slightly increased. But for using these highly sensitive films on industrial scale much higher cost and process efficiency is necessary. Hence, the process was transferred to a highrate sputtering system. A 20 times higher throughput of samples was reached in combination with a higher strain sensitivity compared to the dynamic process in the box coater. The used high‐rate sputtering system is also commercially available with enlarged process chambers which enables for a further up‐scaling for efficiently industrial production.     

A temperature calibration of a temperature/strain transducer based on two strain gauges

The operation of a temperature/strain transducer, called “duplex gauge”, based on two electrical resistance strain gauges, that are temperature compensated for use on materials with different coefficients of linear expansion, was briefly recalled. Three steel specimens were equipped with “duplex gauges” and were subjected to temperature variations and no external loads were applied. The chosen experimental setup (i) to measure the outputs of the gauge temperature compensated for steel and titanium silicate and (ii) to impose known temperature, assured good accuracy and precision in evaluation of the temperature calibration curve. The obtained results showed that the strain differences could be considered, at least for the experimental arrangement examined, a linear function of temperature over the range of 20 to over 140°C. The prepared calibration chart, that allows the correction of temperature induced apparent strain, will be used in future research when generic temperature and strain fields are applied to specimens.     

Piezoresistive response of ITO films deposited at room temperature by magnetron sputtering

Indium tin oxide (ITO) thin films have been deposited on (100) Si substrates by RF magnetron sputtering from a compact target (90% In₂O₃–10% SnO₂ in weight) with 6 in. in diameter. In order to perform electromechanical characterizations of these films, strain gauges were fabricated. An experimental set-up based on bending beam theory was developed to determine the longitudinal piezoresistive coefficient (π_l) of the strain gauges fabricated. It has been confirmed that electrical resistance of the strain gauges decreases with load increases which results a negative gauge factor. A model based on the activation energy was used to explain the origin of this negative signal. The influence of the temperature on piezoresistive properties of ITO films was also evaluated.     

Development of a Vibrating Wire Strain Gauge for Measuring Small Strains in Concrete Beams

Abstract:  A vibrating wire strain gauge capable of measuring strains in concrete elements to an accuracy of better than 0.5  μ ɛ is presented. This offers some advantages over conventional electrical resistance gauges, the quoted accuracy of which is typically 3  μ ɛ , and which are often considered unsuitable for concrete because of their inability to span cracks. While vibrating wire gauges are potentially more accurate, they are prone to significant errors because of temperature changes. In the purpose-built gauge described here, temperature correction is achieved using an unstrained reference gauge. The vibration data are analysed using a moving-window Fourier transformation in order to identify and remove the geometrically nonlinear portion of the response. The resulting system is accurate, economical and easy to use. The gauges have been used to study the behaviour of cracked concrete specimens. Typical results are presented and discussed.     

MEASUREMENT OF INTERNAL STRAIN IN CONCRETE

Methods of strain measurement in concrete have been investigated experimentally. This paper reports work on embedded resistance strain gauges mounted on concrete and other forms of gauge carrier, techniques for strain gauging embedded steelwork, results of gauge factor tests on briquetted and unbriquetted vibrating wire gauges, and gauge responses to temperature variations. Proposals are outlined for future work particularly on stress meters as distinct from strain gauges.     

Measurement of surface strains in GRP products

Current work on fibre composite materials required the measurement of surface strains on glass reinforced plastics (GRP) products subjected to static loading. A study undertaken to account for anomalous results obtained with electrical resistance strain gauges showed that strains measured at a given load, increased with decreasing gauge length and foil gauge resistance. Measurement of localised strains using gauges of length up to 25 mm are subject to considerable discrepancy when compared with gauge lengths of less than 13 mm.