【作者】 李晓敏；

【导师】 朱正吼；

【作者基本信息】 南昌大学 ， 材料学， 2013， 博士

【摘要】 大型装备及重点工程领域常需对壳体、管道等曲面异构组件间的连接状态、使用过程中的受力情况进行实时检测,以准确掌握关键材料及其部件的使用状态、库存性能等重要信息,从而使曲面异构组件间的接触应力敏感性能的测量成为力传感器领域的重要课题。本文以FeCuNbSiB软磁粉为功能填充粒子,以三元嵌段有规共聚硅橡胶为基体材料,采用机械共混和精密铸压热成型方法制备了FeCuNbSiB软磁粉/硅橡胶柔性力敏复合薄膜(简称“FeCuNbSiB/SiR复合薄膜”),较系统地研究了FeCuNbSiB/SiR复合薄膜的制备工艺、微观结构、理化特性等；并循序渐进地设计和开发了FeCuNbSiB/SiR复合薄膜在不同加载方式下的力敏特性测试技术和力敏性能表征方法。在此基础上系统研究了FeCuNbSiB/SiR复合薄膜在不同加载方式下的力敏特性,经大量实验,优化出具有优良力敏性能的FeCuNbSiB/SiR复合薄膜,并针对复合薄膜特有的力敏特性,初步探讨了FeCuNbSiB/SiR复合薄膜的力敏机制；最后,依据优化的力敏薄膜,试制出了柔性接触应力传感器原理样机。本文研究主要取得以下结果：(1)在复合薄膜制备方面：研究和开发了以FeCuNbSiB软磁粉为功能填充粒子、以三元嵌段有规共聚硅橡胶为基体的FeCuNbSiB/SiR力敏复合薄膜,实验可制备的复合薄膜尺寸范围为：长度≤200mmm、宽度≤100mm、厚度50μm～2000μm。研究了软磁粉成分、相结构、粉体粒度及表面性质对复合薄膜物化性能的影响,并对橡胶配方进行优化,解决了软磁粉在橡胶中的均匀分散、橡胶与软磁粉界面控制、复合薄膜厚度控制等问题。研究表明,FeCuNbSiB/SiR复合薄膜的物理机械性能达到了柔性力敏传感器要求,其拉伸强度4.73MPa、扯断伸长率168%、压缩永久变形量3.28%、回弹性51.8%、绍尔A硬度75度。(2)在复合薄膜力敏特性测试和性能表征方面：针对压应力条件下复合薄膜的应力阻抗测试问题,循序渐进地设计开发了静态加载、动态加载、环境温度湿度体系下的加载、静态与动态加载体系下的应力阻抗测试系统,有效地消除了测试系统的不稳定、接触误差等。经过多次反复实验,最终确定“LCR测试+感抗补偿分析”的方法对复合薄膜的力敏特性进行测试,并用Z-σ标准等效曲线表征复合薄膜的力敏特性,用Z-σ标准等效曲线的标准偏差衡量复合薄膜的力敏稳定性,用应力阻抗效应SI%表征复合薄膜力敏灵敏度。优化定型后的复合薄膜力敏性能测试体系由TH2816LCR数字电桥、LYYL-500N高档型微机控制压力试验机、感抗补偿电路等组成,复合薄膜体系采用电容方式连接。测试表征条件定型为：复合薄膜标准规格20mm×20mm、测试频率1kHz、压应力动态加载/卸载速度不大于0.5mm/min、压应力保持加载时间120s。(3)在复合薄膜力敏特性研究方面：研究表明,在测试频率小于100kHz范围内复合薄膜具有良好的力敏特性。随测试频率升高,复合薄膜的力敏敏感度下降；随着压应力增大,复合薄膜的阻抗值下降,力敏敏感度也随之下降。在0.1MPa-0.54MPa压应力范围内,复合薄膜力敏敏感度增幅最大,且呈线性变化；当压应力在0.54MPa-1.5MPa范围内,复合薄膜力敏敏感度增幅渐趋平缓。复合薄膜的厚度、软磁粉粒径、含量及其分散均匀性是影响其力敏特性的主要因素,且上述各因素间存在较强的关联性,其最佳条件的优选需结合软磁粉及其复合薄膜制备工艺的难易程度、可操作性、质量稳定性,特别是实际应用对复合薄膜厚度的限制条件进行综合考虑。通过对复合薄膜力敏特性内外影响因素的优化,复合薄膜具有较佳力敏特性所具备的条件为：测试频率小于100kHz,压应力小于0.5MPa,FeCuNbSiB软磁粉粒径(10-30)μm,且经480℃×1h热处理,FeCuNbSiB软磁粉含量在(22.5-35)vO1%之间,复合薄膜厚度小于300μm,环境温度13℃-50℃。优化后的复合薄膜(FeCuNbSiB软磁粉含量为27.5vO1%、厚度为200+2μm)具有优异的应力敏感性能,在连续加/卸载速率不大于0.5mm/min或保压条件下,测试频率1kHz、压应力0.2MPa-1.0MPa范围内具有良好的力敏稳定性和灵敏性。复合薄膜的SI%值为6%-23%,测试标准偏差稳定在0.02～0.05,在小于0.3MPa的压应力范围内复合薄膜的力敏特性更优。(4)在复合薄膜力敏机制研究方面：通过对复合薄膜的阻抗值Z及分量LC、R和相位角0的频谱特性分析,复合薄膜在交流测试电路中呈现压-容和压-阻特征。整体测试系统的等效电路可以看做是复合薄膜的总电容C与总电阻R并联后再与电路中的电感L串联的结构。影响复合薄膜压-容和压-阻特性的关键因素是复合薄膜模量和粉体含量。研究还发现,该柔性力敏复合薄膜在测试频率为50kHz时具有较为显著的交流阻抗双逾渗特性。(5)通过柔性电路印刷及热压封装技术实现了对优化后的FeCuNbSiB/SiR柔性力敏复合薄膜的封装；复合薄膜进行封装后其应力敏感性能无明显影响,由此制得的柔性接触应力传感器原理样机具有良好的力敏特性和阻抗蠕变性能。FeCuNbSiB/SiR复合薄膜符合柔性接触应力敏传感器的基本要求,具有耐环境性好、绝缘、厚度可控等突出优势,可以作为力敏薄膜使用,有望成为新一代接触应力传感器敏感元材料,具有很好的应用前景。更多还原

【Abstract】 In the fields of large equipment and key engineering, it is necessary to detect the contact stress in the connection status and the use procedure of shell components, piping components and so on by real-time, of which the important information of active condition and inventory performance for the key materials and its parts can be grasped accurately. So the contact stress sensitivity measurement for the components with curved surface structure is becoming an important topic in the field of force sensor.A series of novel flexible stress sensitive composite film of FeCuNbSiB soft magnetic powder/silicone rubber ("FeCuNbSiB/SiR composite film") were successfully fabricated by mechanical blending and precise cast pressure hot forming method, using FeCuNbSiB soft magnetic powder as functional filler particles and ternary block silicone rubber as matrix. The preparation technics, microstructure, physical and chemical properties of FeCuNbSiB/SiR composite film were studied systematically in the paper. Then, the measuring technique and characterization methods for the stress sensitive characteristics of the composite film were designed and developed step by step. On this basis, the stress sensitive characteristics of the composite film under different loading mode was studied systematically and the composite films with excellent stress sensitive property were optimized through a large number of experiments. The stress sensitive mechanism of the FeCuNbSiB/SiR composite film was preliminary discussed based on the peculiar stress sensitive characteristics. Finally, the flexible contact stress sensor prototype system was trial-produced according to the optimized stress sensitive film. The major results obtained in the study are as follows.(1) On the respect of composite film preparation. FeCuNbSiB/SiR stress sensitive composite film was researched and developed based on FeCuNbSiB soft magnetic powder as functional filler particles with stress sensitivity and ternary block silicone rubber as matrix, of which the length, width and thickness of the composite film can be controlled in the range of less than200mm, less than100mm and 50-2000μm, respectively. The effects of filler particle types, phase structure, particle size and surface modification on the physical and chemical properties of FeCuNbSiB/SiR composite film were studied in detail and the rubber compounding was also optimized through vulcanization technology. Thus, such problems as uniform dispersion of soft magnetic powder into the rubber matrix, the interface control between rubber matrix and soft magnetic powder and the thickness control of the composite film, were solved successfully. It shows that the physical and mechanical properties of FeCuNbSiB/SiR composite film can meet the requirements of flexible stress sensitive sensor with4.73MPa tensile strength,168%elongation at break,3.28%compression permanent deformation,51.8%rebound resilience and75A shore hardness.(2) On the respect of the measuring technique and characterization methods for the stress sensitive characteristics of composite film. For the stress-impedance measurement of the composite film under axial forces, the stress-impedance measurement system was designed and developed from static loading, dynamic loading to the static and dynamic loading system, which can eliminate the instability of testing system, and contact error effectively."LCR testing puls inductive reactance compensation analysis" method was adopted to measure the stress sensitive characteristics of the composite film, Z-σ standard equivalent curve to represent the stress sensitive characteristics, standard deviation of Z-σ standard equivalent curve to evaluate the stability of stress sensitive characteristics and the stress impedance effect SI%to represent the sensitivity of the composite film. The optimized system for stress sensitive property measurement is composed by TH2816LCR digital electric bridge, LYYL-500N high-range computer control compression-testing machine, inductance compensation circuit and so on, and the composite film system was connected by capacitance mode. The measurement conditions are set as20mm×20mm for size,1kHz for frequency, less than0.5mm/min for the pressuredynamic loading/unloading speed and120s for the compressive load time.(3) On the respect of the stress sensitive characteristics’research of the composite film. The results show that the stress sensitive characteristics of the composite film are excellent when the test frequency is less than100kHz. The stress sensitivity of the composite film decreases with the increase of the test frequency, and the impedance Z and stress sensitivity of the composite film also decrease with the pressureincreasing. When the pressureis in the range of0.1MPa～0.54MPa, the stress sensitivity presents linear increase and the amplification reaches to maximum value. When the pressureis in the range of0.54MPa～1.5MPa, the stress sensitivity increases slowly and presents nonlinear variation. The thickness of the composite film, the soft magnetic powder’s size, content and its dispersion uniformity are the major factors that can affect the stress sensitivity of the composite film. It is also found that the factors above have strong relationship between each other, so the optimization should be overall considered by the complexity, operability, quality stability of the preparation technics for soft magnetic powder and composite film, especially the limiting conditions for the thickness of the composite film in practical application. Through the optimization of internal and external influencing factors for stress sensitive characteristics of the composite film, the optimum conditions are as follows: the test frequency should be less than100kHz, the pressureless than0.5MPa, the particle size of FeCuNbSiB soft magneitic power in the range of (10～30) μm, the heat treatment condition480℃xlh, the content of FeCuNbSiB in the range of (22.5～35)vol%, the thickness of the composite film less than300μm and the environment temperature13℃～50℃. The optimized composite film with27.5vol%powder content and200±2μm thickness possesses excellent stress sensitivity, stability at the conditions of0.5mm/min continuous load/unload speed or pressure maintaining1kHz frequency and0.2MPa～1.0MPa pressurerange. The value of SI%is6%～23%, the standard deviation is0.02～0.05and the stress sensitivity is more excellent when the pressureis less than0.3MPa.(4) On the respect of stress sensitivity mechanism research of the composite film. It was found that the composite film showed stress-capacitive and stress-resistance characteristic during alternating test circuit by the analysis of spectral characteristics for impedance Z, inductance L, capacitance C, resistance R and phase angle θ. The equivalent circuit of the whole test system is in the structure of total capacitance C and total resistance R’s parallel connection, and series connection with inductance L of the circuit. The key factors to affect the stress-capacitive and stress-resistance characteristic of the composite film are the modulus and powder content. It is special to see that the flexible stress sensitive composites present remarkable double percolation characteristics at the frequency of50kHz.(5) On the respect of the flexible contact stress sensor prototype system. The optimized FeCuNbSiB/SiR composite film was packaged by the flexible circuit printing and hot-press packaging technique. It was found that the stress sensitivity of the composite film after packaging was not been affected obviously. Thus, the flexible contact stress sensor prototype system is provided with good stress sensitivity and impedance creep property produced by the flexible circuit printing and hot-press packaging technique above.FeCuNbSiB/SiR composite film is in accord with the essential requirements of flexible contact stress sensitive sensor, and possessing the prominent dominant of environmental friendly, insulation, thickness control and so on, which is expected’to become a new potential generation of sensitive material used in contact stress sensor field with excellent application prospect.更多还原