高温金属氧化物陶瓷湿敏传感器研究

本文论述了采用湿法合成可在高温下应用的改性羟基磷灰石感湿粉料工艺有关性能，系统研究了应用上述改性ＨＡＰ感湿粉料，采用厚膜丝网印工艺技术制成的湿敏元件和传感器的各项湿敏性能，探讨了有关工艺参数对元件性能的影响，通过中国建筑科学研究院空气调节研究所近两年的系统测试，首次给出了高温下的湿度－电阻特性曲线。     

TiO_2-SnO_2薄膜的湿敏性能研究

采用溶胶-凝胶工艺在印有梳状银电极的石英玻璃表面制备了不同含量Sn2+掺杂的氧化钛薄膜,通过烧结制得一系列湿敏元件,研究了Sn2+掺杂量、烧结温度和工作频率对薄膜湿敏性能的影响。研究表明,较低的工作频率下元件的湿敏性能较好;Sn2+的加入不同程度地降低了TiO2基薄膜的阻抗值,其中TiO2-15wt%SnO2薄膜表现出最高的灵敏度;薄膜高的湿敏性能与Sn2+掺杂引起的晶粒度变化以及热处理过程中的晶型转变有关。     

Al_2O_3湿敏元件的机理与动力学

本期刊1984年第二期,曾概要地介绍了Al_2O_3湿敏元件的发展历史、制作工艺、诸项有关的性能和定量校正的方法。本文将对A1_2O_3湿敏元件的湿敏机理和测湿动力学作一简要的说明,以期对A1_2O_3湿敏元件有一个比较完整的描述。我们已经知道,在Al_2O_3湿敏元件测湿时,外界气相湿度的变化,都会引起元件湿敏介质层中吸(附)水     

高分子材料电阻型湿敏元件的交流电激励预老化处理的实验与研究

采用了交流电激励老化法预处理高分子材料电阻型湿敏元件,并通过测量湿敏元件预处理前后的电阻值和长期跟踪测试来研究其性能变化。结果表明,被适当的交流电激励老化预处理的湿敏元件的感湿特征量的线性和长期稳定性变好了,其它性能变化不大。     

高分子材料电阻型湿敏元件光辐射预老化处理的实验与研究

采用了光辐射预老化处理高分子材料电阻型湿敏元件,并通过测量预处理湿敏元件前后的电阻值和长期跟踪测试来研究其性能变化。结果表明,被适当的光辐射如氦氖激光预老化处理湿敏元件的感湿特征量的长期稳定性变好了,其它性能变化不大。     

HDPE-AA-SSS预辐照接枝膜的表征及其湿敏性能的研究

采用预辐照法将亲水性单体丙烯酸(AA)和对苯乙烯磺酸钠(SSS)接枝到疏水性高密度聚乙烯(HDPE)薄膜上,制备出新型的接枝膜湿敏元件.通过扫描电镜观测了辐照接枝前和接枝后HDPE膜的表面形貌,并通过红外光谱表征了膜的结构,同时测定了接枝膜湿敏元件的湿敏性能.实验结果表明,制备的接枝膜湿敏元件具有良好的湿敏特性,响应和恢复时间短.它具有较好的稳定性,能在高湿、高温环境下使用.实验结果也表明了接枝HDPE膜具有良好的湿敏性能.     

还原温度对氧化石墨烯的湿度-甲醛交叉敏感性能的影响

以氧化石墨烯溶胶为前体,通过旋涂工艺制备薄膜型气敏元件,在低温80～180℃下进行热处理,获得系列不同还原程度的还原氧化石墨烯气敏元件,采用XRD、AFM、FT-IR、XPS对样品的层结构、薄膜厚度及含氧官能团变化属性进行表征,将气敏薄膜元件在相对湿度为11.3%～93.6%的范围内进行预湿处理,并测定元件对甲醛气氛的敏感性能。结果表明:随热还原处理温度的升高,氧化石墨烯的结构逐渐向类石墨结构转变,含氧官能团逐渐脱失,缺陷增多,薄膜的方块电阻呈数量级地减小,从41 MΩ减小至928Ω;经不同湿度预处理的气敏元件置于甲醛气氛中产生了水分子与甲醛分子的竞争吸附,从而导致电阻的明显变化;在10-4甲醛气氛下,未还原或热还原温度较低的气敏元件适用于低、高湿环境下甲醛气氛的气敏测试,最大灵敏度为69.1%,而还原温度适中的元件则适用于中湿环境的甲醛测试,最大灵敏度为80.3%。     

还原温度对氧化石墨烯的湿度-甲醛交叉敏感性能的影响

以氧化石墨烯溶胶为前体，通过旋涂工艺制备薄膜型气敏元件，在低温80～180℃下进行热处理，获得系列不同还原程度的还原氧化石墨烯气敏元件，采用XRD、AFM、FT-IR、XPS对样品的层结构、薄膜厚度及含氧官能团变化属性进行表征，将气敏薄膜元件在相对湿度为11.3%～93.6%的范围内进行预湿处理，并测定元件对甲醛气氛的敏感性能。结果表明：随热还原处理温度的升高，氧化石墨烯的结构逐渐向类石墨结构转变，含氧官能团逐渐脱失，缺陷增多，薄膜的方块电阻呈数量级地减小，从41 MΩ减小至928 Ω；经不同湿度预处理的气敏元件置于甲醛气氛中产生了水分子与甲醛分子的竞争吸附，从而导致电阻的明显变化；在10^?4甲醛气氛下，未还原或热还原温度较低的气敏元件适用于低、高湿环境下甲醛气氛的气敏测试，最大灵敏度为69.1%，而还原温度适中的元件则适用于中湿环境的甲醛测试，最大灵敏度为80.3%。     

纳米湿敏陶瓷α-Fe_2O_3-Al_2O_3-K_2O的制备与性能

采用溶胶—凝胶法新工艺制备了不同配比的纳米级α -Fe2 O3 -Al2 O3 -K2 O复合氧化物湿敏陶瓷。XRD、BET比表面吸附、Archimede排水法等手段对系列纳米陶瓷物相及微结构进行了分析表征。湿敏特性测试结果表明 :调控各组分摩尔配比为r(Fe∶Al∶K) =90∶5∶5,可获得全湿区阻—湿特性线性关系良好、感湿灵敏度较高、湿滞小、使用温度范围宽、响应速度较快、性能一致性优的湿敏元件。提出组份间界面作用模型 ,并初步探讨了影响材料阻—湿特性及湿滞的内在因素     

专利技术

专利申请号 :8710 1847　　公开号 :10 2 0 910专利名称 :石墨法制造多孔陶瓷湿敏元件文摘 :本发明公开一种加石墨制造多孔陶瓷湿敏元件的方法。选择 80ＣｏＯ— 2 0Ｃｏ(Ｃｏ -[0 .7]Ｆｅ -[1.3] )Ｏ4 陶瓷材料 ,借助外加石墨粉 ,在恒定的成形压力和烧结温度下 ,制造多孔陶瓷 ,气孔率为 10 %～ 40 %。外加石墨量为 5 %～ 2 0 %时 ,可得最佳湿敏特性。制造的陶瓷湿敏元件 ,具有一致的机械、化学和电气性能 ,并且不需加热清洗、高稳定和长寿命。加石墨法用于其他配方 ,也可得到良好的效果。 (化　专 )专利申请号 :8710 15 5 1　　公开号 :10 …     

Ultrasensitive and reversible room-temperature resistive humidity sensor based on layered two-dimensional titanium carbide

The nanostructured two-dimensional (2D) materials for humidity sensing applications have become increasingly attractive. However, 2D materials have negative aspects of easily stacking and agglomerating multilayers. Here, a novel resistive-type humidity sensor utilizing multi-layer titanium carbide (Ti₃C₂T_x) films as sensitive material is demonstrated. The humidity sensor exhibits an ultrasensitive and reversible sensing performance in a wide relative humidity range. Furthermore, the ultrafast response and recovery properties are achieved at room temperature. The Fourier transform infrared spectroscopy is used to investigate the adsorption of water vapor on Ti₃C₂T_x surfaces. A rapid capillary condensation of water vapor on the unique accordion-like microstructures and the hierarchical nanostructures of hydroxyl-riched Ti₃C₂T_x surface are supposed to be responsible for the super adsorption capability for water vapor. The electrostatic field induced by adsorbed water molecules is proposed to explain the resistance change of the titanium carbide humidity sensor. This work highlights the unique advantages of humidity sensor with layered 2D materials of Ti₃C₂T_x MXenes, including ultrasensitive, good reversibility and fast recovery at room temperature.     

FREEZE DRYING WORLD UPDATE IN DRYING TECHNOLOGY

Spectral Sciences, Inc. is developing a multipoint humidity monitor for drying application in the pulp and paper industry. The humidity is measured by monitoring near-infrared optical absorption in the process stream atmosphere. An array of sensor heads distributed throughout the plant is linked by fiber optic cables to a single source/readout device which can be located in a control room hundreds of meters away. The sensor heads and cables are modular. allowing for raid installation and reconfiguration of a distributed sensor system in process control applications. The method used for quantifying the optical absorption provides substantial stability, accuracy, and signal processing advantages over standard wavelength scanning or band pass techniques. The laser diode's output wavelength is actively locked to the center of a water absorption line, thereby providing a constant monitor of water vapor concentration which is insensitive to all other species in the process stream. Wavelength modulation and second harmonic detection techniques are used to quantify the water vapor concentration. A simultaneous temperature measurement then permits an output of the absolute humidity or humidity ratio for process monitoring or control     

MULTIPOINT FIBEROPTIC HUMIDITY MONITOR

Spectral Sciences, Inc. is developing a multipoint humidity monitor for drying application in the pulp and paper industry. The humidity is measured by monitoring near-infrared optical absorption in the process stream atmosphere. An array of sensor heads distributed throughout the plant is linked by fiber optic cables to a single source/readout device which can be located in a control room hundreds of meters away. The sensor heads and cables are modular. allowing for raid installation and reconfiguration of a distributed sensor system in process control applications. The method used for quantifying the optical absorption provides substantial stability, accuracy, and signal processing advantages over standard wavelength scanning or band pass techniques. The laser diode's output wavelength is actively locked to the center of a water absorption line, thereby providing a constant monitor of water vapor concentration which is insensitive to all other species in the process stream. Wavelength modulation and second harmonic detection techniques are used to quantify the water vapor concentration. A simultaneous temperature measurement then permits an output of the absolute humidity or humidity ratio for process monitoring or control     

Fast-curing adhesive compositions based on modified epoxy resins

The properties of two new fast-curing adhesive materials based on modified cold-curing epoxy resins are studied. The studied materials are used for the repair and production of complex technological equipment. The properties of fast-curing adhesives developed in Germany and Russia (OAO Kompozit) are compared, and it is shown that the strength properties of new adhesive materials are not inferior to foreign analogs and are distinguished by a high curing rate at room temperature; they display good service properties at high temperatures and enhanced humidity. The fields of application of the adhesives for bonding parts made of aluminum alloys and glass-and carbon-reinforced plastics are indicated.     

Low concentration ethanol sensor based on graphene/ZnO nanowires

Metal-oxide based gas sensors are widely used as the gas sensing elements in industrial and residential areas. Many efforts have been made to increase sensitivity and reduce the working temperature of metal-oxide based gas sensors. In this paper, ZnO nanowires (NWs) were successfully grown on graphene (Gr) nanosheets by the hydrothermal method. The synthesized Gr/ZnO NWs nanocomposite were investigated as the sensing material. Not only is the sensor response much higher, it also works in a lower working temperature toward a low concentration of ethanol in comparison with pure ZnO NWs. The optimum working temperature is reduced from 200 °C in pure ZnO NWs to 125 in Gr/ZnO NWs sensor. The maximum response of the Gr/ZnO NWs sensor is 26, which is approximately enhanced twice as much as the pure ZnO NWs sensor. The lower limit of detection (LLOD) of the proposed sensor is as low as 1 ppm ethanol vapor. The sensor was shown a high response, good selectivity, fast response toward ethanol vapor, excellent repeatability, and low sensitivity toward a high relative humidity, as well as remarkable long-term stability.     

A Novel Highly Sensitive Humidity Sensor Based on ZnO/SBA‐15 Hybrid Nanocomposite

This work deals with the study of hydrothermally synthesized zinc oxide (ZnO) loaded mesoporous SBA‐15 hybrid nanocomposite for relative humidity sensing (RH) at room temperature. The sensor exhibits an excellent ~5 orders impedance change along with excellent linearity, quick response time (17 s), rapid recovery time (18 s), negligible hysteresis (1.2%), good repeatability, and stability (1.8%) in 11%–98% RH range. In addition, complex impedance spectra of the sensor at different RHs were analyzed to understand the humidity sensing mechanism. Our study can open a new way for realizing ZnO/SBA‐15 hybrid nanocomposite for fabrication of high‐performance RH sensors.     

5428/T700复合材料的耐湿热性能

5428树脂是一种高韧性改性双马树脂，通过对5428／T700复合材料的吸湿率、不同吸湿条件下的玻璃化转变温度（Tg）及高温湿态学性能进行研究，结果表明5428／T700复合材料的饱和吸湿率仅为0．82％左右，温、湿度对其Tg的影响较小，故体系具有良好的耐湿热能力。     

A nanoporous thin-film miniature interdigitated capacitive impedance sensor for measuring humidity

This paper presents a development of a low-cost miniature humidity sensor with an interdigitated aluminium electrode connected in parallel on quartz substrate. Interdigitated capacitive device has been fabricated using the photolithography method. The aluminium electrode was covered with sensitive film of a nanoporous thin film of γ-Al₂O₃ made from novel sol–gel technique. Nanostructured thin film offers very high surface to volume ratio with distribution of micro pores for moisture detection. Pore morphologies of the film have been studied by field emission electron microscope and X-ray diffraction methods. Impedance measurement of the miniature capacitive humidity sensor toward relative humidity was investigated at room temperature by Agilent 4294A impedance analyzer (Agilent, Santa Clara, CA, USA). The device exhibits short response and recovery times and good repeatability.     

改性羟基磷灰石对水体中五价钒的吸附

随着工业的发展,水体重金属污染逐渐成为环境污染的重要组成部分,寻求环境友好型材料来治理水体重金属污染已成为当今环境科学研究的热点之一.以Ca(NO3)2· 4H2O和(NH4)2HPO4为原料,利用溶液共沉淀法制备羟基磷灰石,并采用聚乙二醇对其改性,得到改性羟基磷灰石,并用其对水体中的钒污染物进行吸附研究.单因素吸附实验表明,溶液pH值、吸附剂投加量、吸附时间和环境温度均会对吸附产生影响.在钒浓度为100 mg· L-1,溶液pH值为5.00的条件下,当改性羟基磷灰石投加量为10 g· L-1时,吸附趋于平衡,得到最大吸附率95.2%.在一定条件下,聚乙二醇改性羟基磷灰石可用于水体钒污染的修复.     

基于硝化纳米纤维素/琼脂的高灵敏度湿度传感器

湿敏材料是决定湿度传感器性能的关键,本研究将具有特殊化学结构的纤维素和琼脂这两种生物质材料有机结合起来,制备具有不同湿度敏感性的硝化纳米纤维素/琼脂（nitrocellulose nanocrystals/Agar,NCNCs/Agar）复合敏感膜材料,基于石英晶体微天平（quartz crystal microbalance,QCM）制备出具有高灵敏度的湿度传感器。结果表明,NCNCs/Agar复合敏感膜修饰的QCM湿度传感器的灵敏度和频率响应值较单一材料敏感膜修饰的QCM均有较明显的提高。经过优化测试,得到NCNCs与琼脂的最佳质量比为1∶25,涂覆2.049μg敏感材料的QCM传感器（QCM-b）性能最优异。在相对湿度（RH）11%~84%下,QCM-b具有良好的线性（R²=0.9933）,灵敏度为32.54Hz/%RH。在RH 11%~97%下,QCM-b响应值可达到-5820Hz,具有优异的对数拟合系数（R²=0.9994）,恢复时间短（5s）,并且具有良好的重现性和长期稳定性,显示出在湿度探测领域的良好应用前景。