航空碳石墨密封材料试验方法的建立

由于碳石墨密封材料具有良好的摩擦磨损性能,因此在航空动密封材料中占有重要的位置。 六十年代中期,我们对美国J57、J75、J69、J79等发动机的各类结构碳石墨密封材料样件进行了全面分析,并同时开始了我们自己的航空用碳石墨密封材料的研制工作。所研制的材料通过模拟和装机试验,得到了若干个接近和达到国外样件水平的材料。目前,国内自行研制和生产的航空用碳石墨密封材料进入航标的牌号,基本满足了当前各机种的使用要求。 航空用碳石墨密封材料的工作条件(接触压力、环境介质、温度和线速度等)和性能要求,是一般机械用碳所难以满足的。所以要建立碳石墨密封材料的航标和满足航标性能测试要求的试验方法。     

标准样件的计量确认方法

标准样件在科研生产过程中用于量值传递，它的性能直接关系着产品的质量。本文结合我院标准样件的具体情况，提出了标准样件计量确认方法，给出了详细的测试实施步骤，总结出了标准样件计量确认的注意事项，通过这项工作使标准样件的计量进一步规范化。     

基于PVDF薄膜的智能材料回声控制实现

提出了用高分子压电材料——PVDF薄膜作为激励声源，将其内嵌于基体材料聚氨酯橡胶中制成具有特殊功能的消声材料。通过声时延的方法，用布置在消声样件前方的两传声器检测出平面入射声波和反射声波，利用压电材料PVDF薄膜的逆压电性能，对其施加具有一定幅值和相位的电压，实现样件材料的声阻抗和介质声阻抗的匹配，以使得反射声波达到最小或零，从而实现回声控制的目的。最后对不同频率的入射声波进行了基于声阻抗管的回声控制实验测试并对结果进行了分析。     

3D打印TPU材料的力学性能及模型参数研究

为了解决柔顺机构在优化设计过程中试验及性能验证困难的问题，采用3D打印技术对热塑性聚氨酯（thermoplastic polyurethane,TPU）材料的力学性能进行了试验研究。分析了材料硬度和打印填充率对TPU材料力学性能的影响，获得了TPU材料较佳的3D打印参数。进行单因素和两因素试验并结合方差分析，确定了显著影响TPU试样柔性的主次因素分别为TPU材料硬度和打印填充率。结合TPU材料的力学性能试验数据，得到了Mooney-Rivlin、Yeoh、Ogden、Valanis-Landel等4种常用超弹性材料本构模型的材料参数与材料硬度、打印填充率之间的映射关系。研究表明：随着TPU材料硬度和打印填充率增大，试样的柔性减弱；在4种超弹性模型中，Ogden模型对于不同打印参数下的TPU试样都具有较好的力学性能预测效果；4种模型在相同TPU硬度、不同打印填充率下的预测效果没有明显差别。研究结果可以为TPU材料的3D打印和有限元仿真分析提供参考，为柔顺机构在设计过程中的试验、性能验证及样件制作提供可靠的技术支撑。     

表面粗化工艺对IPMC的制备及性能的影响

基于二次渗透还原法对IPMC材料的制备进行研究.探索3种不同的基膜表面粗化方法对IPMC材料特性的影响.表面粗化方法包括手工打磨、砂光机打磨以及等离子体表面处理方法.通过样件实测对3种不同粗化条件下获得的IPMC材料的外观特征、微现形貌、驱动变形特性以及表面电阻特性进行了测试和比较.实验结果表明,随着表面粗化均匀程度的提高,基膜表面及内部金属沉积均匀与致密性增高,材料的驱动变形能力降低.在一定的驱动电压范围内,IPMC材料的变形与电压近似成线形增加的关系.在相同的尺寸、约束以及驱动电压(3V)条件下,手工打磨的样件能够产生60°的弯曲变形,砂光机打磨样件为45°,而等离子体处理的样件只有15°.     

仿生阻尼材料研究

自然生物体结构经过漫长的进化,在减振和隔振等方面已经达到较高的效率。本文以大型陆生哺乳动物的皮层结构为仿生对象,根据其皮层的结构特征,从材料参数和结构两方面模仿其生物构造,设计出一种片状仿生类阻尼减振材料样件,并对该材料进行了台架试验,结果表明,该仿生阻尼材料有较为显著的减振降噪效果。     

高速入水冲击下传感器的聚氨酯防护研究

随着现代工业的发展与提高,现代测量技术针对高速入水结构测量传感器的防护工作提出了要求。通过对三种不同硬度,体系同为PTMG配方的聚氨酯弹性体试片进行拉伸试验、粘接性能试验获取材料的力学及粘接性能参数。进一步采用Ansys-Workbench显式动力学分析软件对防护模型在高速入水冲击过程进行仿真分析,从而得出一种硬度的聚氨酯材料满足冲击环境要求。最后通过防护样件的试验冲击考核结果,说明聚氨酯弹性体作为高速入水冲击下传感器防护的可行性。     

不锈钢低压真空渗氮组织与性能研究

本文以304奥氏体不锈钢样件为试验研究对象,在8h、400℃、不同气压条件下对样件进行了低压真空离子渗氮试验,研究分析了不同气压下低压真空离子渗氮组织与其性能(离子渗氮后的组织、渗氮层厚度、硬度、耐磨性)的变化,并得出了相应的结论。     

振动利用对FDM薄板动力学性能的影响研究

熔融沉积成型(FDM)是当今迅速发展起来的一种快速成型技术(也称3D打印技术),在一定时间内能够直接打印出具有复杂几何形状的模型或零件。然而,FDM产品在机械性能方面却很难与传统加工方式生产的零件相媲美,成为了制约该项技术发展的重要因素之一。首次提出利用振动提高FDM薄板的动力学特性的新方法:将振动引入FDM过程,建立了振动式FDM 3D打印机;分别制备了引入振动前、后Z和X两个打印方向的试验样件,并进行了相应的锤击法模态试验;对比分析利用振动进行加工的FDM样件和普通样件的试验结果,确定振动利用对FDM薄板动力学性能的影响规律。研究表明,利用振动能够使FDM薄板的固有频率发生改变,有效降低其共振响应,提高模态阻尼比,从而提高FDM薄板的阻尼减振性能。     

3D打印形状记忆智能剪纸结构

目的 探究不同切口及不同打印角度形状记忆剪纸结构的拉伸力学性能及形状记忆恢复性能,获得具有较好变形能力和形状记忆恢复能力的智能化剪纸结构。方法 使用FDM打印不同角度的剪纸结构样件,并利用激光切割机获得具有方形切口和圆形切口的样件。对打印角度为0°/90°、±45°的方形切口和圆形切口样件进行常温拉伸实验。为探究温度的影响,进行高温缓慢拉伸实验和高温快速拉伸实验;对比方形切口件和圆形切口件在不同初始应变下的形状记忆恢复能力。结果 在常温下,打印角度为0°/90°的方形切口样件的拉伸距离为1.75 mm,圆形切口样件的拉伸距离为2.50 mm;±45°打印角度的方形切口样件的拉伸距离为3.25 mm,圆形切口样件的拉伸距离为3.00 mm。在高温下,材料进入高弹态,2种切口样件在200%拉伸应变下均未断裂;提高拉伸速率后,方形切口样件的拉伸应变为243.8%,圆形切口样件的拉伸应变为337.5%。结论 将打印角度从0°/90°改为±45°后,方形切口和圆形切口剪纸结构的变形能力均增强。相比于方形切口,圆形切口剪纸结构具有更好的变形能力。高温下剪纸结构的变形能力大大增强;圆形切口剪纸结构样件的形状记忆恢复能力强于方形切口样件的。     

Effects of the type of polycation on the amperometric response of choline biosensors prepared by a layer-by-layer deposition technique

A layer-by-layer deposition technique was employed for fabricating choline biosensors using chloline oxidase (ChOx) and polycations such as poly(ethyleneimine) (PEI) and poly(diallyldimethylammonium chloride) (PDDA). A platinum electrode was coated with ChOx/PEI or ChOx/PDDA thin film to prepare amperometric choline sensors. The amperometric response of the sensors depended significantly on the type of the polycations. The ChOx/PDDA film suppressed the permeation of choline, resulting in a lower response than that of the ChOx/PEI film-based sensors. The results were rationalized based on the different chemical structures of the polycationic materials.     

氢敏材料及氢气传感器的研究进展

对氢气进行快速、准确、原位测量,具有重要的学术意义和广阔的应用前景.氢气传感器发高品质氢敏材料的研制,氢敏材料的敏感响应性、重现性等决定着氢气传感器的工作性能.综述了近年来研究较多的半导体型、热电型、光学型、电化学型4类氢气传感器及相应氢敏材料的研究进展,并展望了氢敏材料及氢气传感器的发展方向.     

基于微结构的柔性压力传感器设计、制备及性能

随着科技的快速发展,电子皮肤和柔性可穿戴设备由于在人体运动、健康监测、智能机器人等领域具有重要应用而引起了人们广泛的关注。传统的基于贵金属或金属氧化物半导体的压力传感器成本高、柔韧性差,而新型的基于微结构的柔性压力传感器具有灵敏度高、应变范围宽、低成本、低功耗、响应速度快等优势,在电子皮肤和柔性可穿戴设备等方面发挥重要作用,成为当前柔性电子材料与器件主要研究热点之一。本文系统总结了近年来颇受关注的基于金字塔形、微球形、微柱形、仿生结构、褶皱等不同柔性基底微结构和多孔导电聚合物材料的柔性压力传感器在材料选择、结构设计、制备方法、传感性能等方面取得的重要进展,并对柔性压力传感器的未来发展进行了展望。      

A high sensitivity gas sensor for formaldehyde based on CdO and In(2)O(3) doped nanocrystalline SnO(2)

The gas-sensing characteristics of In(2)O(3) and CdO doped nanocrystalline SnO(2) compounds for formaldehyde were investigated in this study. The phases of the resulting materials and the morphologies of the sensing layers were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Indirect-heating sensors using SnO(2)-In(2)O(3)-CdO compounds as sensitive materials were fabricated on an alumina tube with Au electrodes and platinum wires. All measurements were performed at several operating temperatures from 100 to 180?°C. Good gas-sensing responses to formaldehyde have been found for all the prepared samples. It is shown that the sensors exhibited high sensitivity at low operating temperature (133?°C), making them promising candidates for practical detectors for formaldehyde.     

基于碳纳米材料的肾上腺素电化学传感器研究进展

肾上腺素(AD)作为一种神经递质在人体内扮演重要角色,其含量的高低直接影响人体身体健康,因此对AD进行快速检测具有重要的实际意义。其检测方法中电化学方法具有灵敏度高、检测速度快、操作简便的优点,因而构建性能优异的肾上腺素电化学传感器成为研究热点。为提高传感器的电化学性能,碳纳米材料被采纳作为修饰传感器的新型材料而广泛应用,取得了检测限低、灵敏度高并有希望应用于临床检测的巨大进步。本文从碳点、石墨烯、碳纳米颗粒等碳纳米材料出发,分析AD在电极表面的电氧化还原机制,对近年来基于碳纳米材料的肾上腺素电化学传感器制备方法及检测结果进行分类统计,并对今后的检测提出展望,以期获得更有效的肾上腺素电化学传感器。     

Comparison between point and long‐gage FBG‐based strain sensors during a railway bridge load test

Strain is a key parameter in laboratory and bridge load testing. The selection of a strain sensor depends on several factors, including the aim of the test and the specimen material. The application of the right sensor is vital to obtain accurate readings, especially in the case of heterogeneous materials such as concrete. This paper focuses on long‐gage and point fiber Bragg grating‐based strain sensors and their possible applications on concrete elements. First, strain sensors are described, after which long‐gage and point fiber Bragg grating strain sensors are compared in a concrete specimen test, a concrete column test and static and dynamic load tests on a concrete railway bridge. Results show that although it is advisable to use long‐gage sensors when monitoring heterogeneous materials, there are some particular cases were both sensors type can provide accurate strain measurements.     

Doping and defect association in oxides for use in oxygen sensors

Oxygen sensors provide valuable information for improving the efficiency of, and thus reducing harmful emissions from, combustion processes, such as in internal combustion engines. Oxide materials can be used in different ways to generate an oxygen partial pressure dependent output. The type of sensor in which a particular oxide is used depends on the ionic and electronic defects in the oxide, which can be, to some extent, controlled by doping. In this paper, the issues in selection of an oxide for use in resistive-type, potentiometric-type and amperometric-type oxygen sensors are reviewed. Prototypical examples of materials, specifically titania and zirconia, commonly used in these sensors are discussed to illustrate the effects of doping and defect interaction on the electrolytic and transport properties of oxide materials for use in oxygen sensors.     

Hybrid Films of Graphene and Carbon Nanotubes for High Performance Chemical and Temperature Sensing Applications

A hybrid composite material of graphene and carbon nanotube (CNT) for high performance chemical and temperature sensors is reported. Integration of 1D and 2D carbon materials into hybrid carbon composites is achieved by coupling graphene and CNT through poly(ionic liquid) (PIL) mediated‐hybridization. The resulting CNT/PIL/graphene hybrid materials are explored as active materials in chemical and temperature sensors. For chemical sensing application, the hybrid composite is integrated into a chemo‐resistive sensor to detect a general class of volatile organic compounds. Compared with the graphene‐only devices, the hybrid film device showed an improved performance with high sensitivity at ppm level, low detection limit, and fast signal response/recovery. To further demonstrate the potential of the hybrid films, a temperature sensor is fabricated. The CNT/PIL/graphene hybrid materials are highly responsive to small temperature gradient with fast response, high sensitivity, and stability, which may offer a new platform for the thermoelectric temperature sensors.     

高灵敏Love波传感器及其关键材料

Love波传感器是声表面波传感器的一种,其灵敏度最高.对Love波生物、化学传感器的研究现状进行了综述,着重分析了波导材料及其厚度、基板材料及其切向对传感器的灵敏度及温度稳定性的影响关系.指出采用高频谐振型的器件结构并结合聚合物波导的方案可进一步提高Love波传感器的灵敏度.     

Molecule–Graphene Hybrid Materials with Tunable Mechanoresponse: Highly Sensitive Pressure Sensors for Health Monitoring

The development of pressure sensors is crucial for the implementation of electronic skins and for health monitoring integrated into novel wearable devices. Tremendous effort is devoted toward improving their sensitivity, e.g., by employing microstructured electrodes or active materials through cumbersome processes. Here, a radically new type of piezoresistive pressure sensor based on a millefeuille‐like architecture of reduced graphene oxide (rGO) intercalated by covalently tethered molecular pillars holding on‐demand mechanical properties are fabricated. By applying a tiny pressure to the multilayer structure, the electron tunnelling ruling the charge transport between successive rGO sheets yields a colossal decrease in the material's electrical resistance. Significantly, the intrinsic rigidity of the molecular pillars employed enables the fine‐tuning of the sensor's sensitivity, reaching sensitivities as high as 0.82 kPa^?1 in the low pressure region (0–0.6 kPa), with short response times (≈24 ms) and detection limit (7 Pa). The pressure sensors enable efficient heartbeat monitoring and can be easily transformed into a matrix capable of providing a 3D map of the pressure exerted by different objects.