纳米Al2O3掺杂对厚膜应变电阻性能的影响

采用粒子尺寸为８ｎｍ的纳米Ａｌ２Ｏ３作掺杂改性剂，通过选择合适粒径和配比的导电相、玻璃及烧结工艺，得到一种ＧＦ为１３、电阻温度系数小、稳定性良好的在厚膜应变电阻，并从厚膜电阻导电机理和纳米材料特性出发。     

厚膜电阻的研究现状及发展趋势

首先描述了厚膜电阻的基本结构,介绍了制作厚膜电阻的各种材料,然后详细地阐述了厚膜电阻的制备工艺,探讨了厚膜电阻的导电机理和近年来的发展趋势。     

BaPbO3/Ag复合体系大功率厚膜电阻浆料的研究

提出以BaPbO3/Ag复合体系作为功能相制备低成本大功率厚膜电阻浆料的思想,研究Ag含量、峰值烧结温度对厚膜电阻电性能和热稳定性的影响,并从导电机理方面对实验结果进行了分析讨论.     

掺杂Al2O3纳米粉对ZnO厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Al2O3纳米粉(平均粒径5 nm)为原料,利用传统的厚膜气敏传感器制备工艺制备了纯ZnO厚膜气敏传感器和掺杂Al2O3(掺杂量为2wt%和5wt%)的ZnO厚膜气敏传感器.对这三种厚膜传感器的本征电阻及对乙醇蒸汽的敏感特性进行了测试.结果表明:掺杂少量Al2O3纳米粉可明显降低ZnO气敏传感器的本征电阻,改善传感器的烧结性能,同时还可降低其最佳工作温度,提高器件对乙醇的灵敏度.结合厚膜气敏传感器的显微结构分析结果,对出现上述差异的原因进行了讨论.     

厚膜力传感器的一体化补偿

对以陶瓷双孔梁为弹性体的新型厚膜力传感器进行了零点温度漂移和零点的一体化补偿，分析了零点温度漂移和零点的补偿方法，在同一陶瓷弹性体上印刷，烧结，制备了厚膜力敏电阻，补偿厚膜热敏电阻零点补偿厚膜电阻，并较好地是实现了零点温度漂移和零点的补偿，还探讨了补偿用热敏电阻浆料性能的改进。     

厚膜浆料的物化特性与厚膜电阻力敏特性的关系

厚膜压力传感器具有优良的性能和广阔的应用前景。厚膜浆料的研究在传感器研制中超着非常重要的作用。本文主要讨论表征浆料物化特性、工艺配方的几个重要参数(导电相的浓度和颗粒度,玻璃粉的粒度与化学组成)对厚膜电阻 R、GF 和 TCR 的影响。同时,借助于 SEM 和 XRD 等分析手段,对厚膜电阻的导电机理、力敏特性与浆料物化特性之间的关系也进行了一些探讨。     

掺杂Fe_2O_3对ZnO多孔纳米固体厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Fe2O3,纳米粉(平均粒径90 nm)为原料,利用传统的厚膜气敏传感器制备工艺,制备了纯ZnO多孔纳米固体厚膜气敏传感器和掺杂Fe2O3(掺杂量为1wt%,2wt%和5wt%)的ZnO厚膜气敏传感器.分别测试了这四种厚膜气敏传感器的本征电阻(传感器在空气中的电阻值)及其对乙醇,汽油,丙酮,对二甲苯,氢气,甲烷和CO敏感特性.结果表明:当工作温度在较低时,Fe2O13,的掺杂可明显降低ZnO多孔纳米固体厚膜气敏传感器的本征电阻,并提高其工作稳定性,而适量Fe2O3的掺杂可以提高ZnO多孔纳米固体厚膜气敏传感器对乙醇蒸气和汽油的灵敏度.结合对传感器厚膜的显微结构分析结果,我们对出现上述差异的原因进行了初步讨论.     

厚膜力传感器的─体化补偿

对以陶瓷双孔梁为弹性体的新型厚膜力传感器进行了零点温度漂移和零点的─体化补偿。分析了零点温度漂移和零点的补偿方法，在同一陶瓷弹性体上印刷、烧结、制备了厚膜力敏电阻，补偿厚膜热敏电阻及零点补偿厚膜电阻，并较好地是实现了零点温度漂移和零点的补偿。还探讨了补偿用热敏电阻浆料性能的改进。     

ZnO多孔纳米固体厚膜气敏传感器的制备和性质表征

以ZnO纳米粉(平均粒径30nm)为原料,利用水热热压方法制备了多孔的ZnO体块纳米固体,测试了以多孔纳米固体为原料制成的厚膜气敏传感器对挥发性有机化合物(VOCs)乙醇、丙酮、苯、甲苯和二甲苯蒸气的气敏特性,并与用ZnO纳米粉制备的厚膜传感器进行了比较.结果发现,与ZnO纳米粉相比,用ZnO多孔纳米固体制备的厚膜传感器在空气中的电阻大大减小,最佳敏感温度降低、响应时间和恢复时间大大缩短.通过综合分析ZnO纳米粉和ZnO多孔纳米固体的XRD、TEM及厚膜传感器的SEM测试结果研究了厚膜传感器气敏特性的差异.     

利用纳米ZnO粉制备厚膜气敏传感器的研究

以ZnO纳米粉(平均粒径30nm)为原料,利用水热热压方法制备了ZnO多孔纳米固体,同时用通常的水热法对ZnO纳米粉进行了预处理(预处理ZnO纳米粉)。然后,分别以ZnO多孔纳米固体和预处理ZnO纳米粉为原料,制备了厚膜气敏传感器。本征电阻的测试结果表明,这两种厚膜气敏传感器的本征电阻比用未经处理的ZnO纳米粉(以下简称“原料ZnO纳米粉”)制备的厚膜气敏传感器大大降低并很快达到稳定状态。有效地改善了器件工作的稳定性。结合对三种传感器的显微结构分析,对出现上述差异的原因进行了讨论。     

Subsolidus phase equilibria in the CaO-poor part of the RuO2-CaO-SiO2 system

During firing the conductive phase based on CaRuO₃ in lead-free thick-film resistors decomposes, presumably due to interactions with the silica-rich glass phase. Subsolidus equilibria in the CaO-poor part of the RuO₂-CaO-SiO₂ diagram were studied with the aim of investigating possible interactions between the conductive phase and silica-rich glasses in thick-film resistors. The tie lines are between CaRuO₃ and CaSiO₃, and between RuO₂ and CaSiO₃. This indicates that the calcium ruthenate is not stable in the presence of the silica-rich glass phase.     

Microsphere‐Assisted Robust Epidermal Strain Gauge for Static and Dynamic Gesture Recognition

A novel and robust epidermal strain gauge by using 3D microsphere arrays to immobilize, connect, and protect a multiwalled carbon nanotubes (MWNTs) pathway is presented. During the solvent deposition process, MWNTs sedimentate, self‐assemble, and wrap onto surface of polystyrene (PS) microspheres to construct conductive networks, which further obtain excellent stretchability of 100% by combining with commercially used elastomer. Benefiting from its 3D conductive pathway defined by microspheres, immobilized MWNT (I‐MWNT) network can be directly used in practical occasions without further packaging and is proved by tape tests to be capable of defend mechanical damage effectively from external environment. By parameter optimization, the strain sensor with 3 µm PS spheres obtains stable resistive responses for more than 1000 times, and maintains its gauge factor (GF) of 1.35. This thin‐film conductive membrane built by this effective construction method can be easily attached onto fingers of both robot and human, and is demonstrated in sensitive epidermal strain sensing and recognizing different hand gestures effectively, in static and dynamic modes, respectively.     

Effect of inorganic binders on the properties of silver thick films

The technology for realizing conductive thick films from metal powders is of considerable importance in the manufacture of various electronic devices, such as hybrid integrated circuits, multilayer ceramic capacitors, three-dimensional circuits for mobile communication, etc. Silver thick films have been extensively used to provide electrical contacts in silicon solar cells, hybrid circuits, and other devices, as they have the lowest resistivity as well as the lowest cost among the noble metals. Metal powders for thick-film pastes are normally obtained through chemical precipitation from an aqueous or organic solution of their corresponding salts. This method is able to provide the desired particle shape and size and also offers a low preparation cost. In this paper, we have reported the effect of inorganic binders on the properties of silver thick films. The thick-film pastes were formulated from specially treated silver powders and using the three different types of inorganic binders such as glass frit, metal oxides, and a mixture of both. The effect of these inorganic binders on the surface structure, adhesion with alumina, solderability, and electrical properties was determined by analyzing the physical and chemical behavior of the inorganic binders in the silver thick films during firing. The films with an addition of glass frit and mixtures of glass frit and metal oxide did not provide good adhesion and solderability simultaneously. However, the silver thick films containing 10 wt % bismuth oxides exhibited excellent characteristics, i.e. high adhesion strength, good solderability, and low sheet resistivity. As expected, the adhesion strength decreased with decrease in the binder content.     

The influence of precursor powders and processing parameters on the properties of SnO2-based gas sensors

Semiconducting tin oxide precursor powders were synthesized via three different chemical processing routes. The influence of powder processing conditions on the physical properties, e.g., particle size, surface area and phase composition of both uncalcined and calcined materials, was investigated. These powders were used to fabricate gas sensors using thick-film screen-printing technology. The effect of precursor powders, sintering conditions, sensor temperature and Pd catalyst on the carbon monoxide, methane, propane and ethanol gas sensing characteristics of the sensors were investigated. Sensors were also fabricated using tin oxide powders obtained from a commercial source and their gas sensing properties were also investigated. The data indicates that the powder processing methodology, sensor fabrication conditions and Pd catalyst can profoundly influence the physical characteristics as well as the gas sensing properties of the sensors.     

The development of the microstructural and electrical characteristics of NTC thick-film thermistors during firing

One kohm/sq. thick-film NTC thermistors (4993, EMCA Remex) with high, non-linear and negative temperature coefficients of resistivity were fired at different temperatures. The development of the resistors’ conductive phase and microstructure was investigated by X-ray diffraction analysis and by scanning electron microscopy. Sheet resistivities, beta factors and noise indices were measured as a function of the firing temperature. In the fired layers of the thermistors the X-ray analyses showed mainly spinel phase and RuO₂, which is added to the thick-film NTC materials to decrease the specific resistance and to improve the stability and the current noise. Higher firing temperatures led to more densely sintered microstructures, to increased resistivities and to higher beta factors. The higher resistivities were attributed to the partial exchange of ions on the “B” sites of the spinel structure with aluminium ions.     

A characterisation of thick film resistors for strain gauge applications

Some commercial thick film resistors with sheet resistivities from 1 kohm/sq. up to 1 Mohm/sq. were evaluated for strain gauge applications. Temperature coefficients of resistivity, noise indices and gauge factors (GFs) were measured. For the same resistor series GFs and noise indices increase with increasing sheet resistivity. However, both GFs and noise indices are different for resistors with the same nominal sheet resistivity but from different resistor series. The results indicated that the microstructure rather than the different chemical composition of the conductive phase in thick film resistors is the primary reason for the different gauge factors.     

Further examinations of carbon/polyesterimide thick-film resistors

A carbon (carbon black and/or graphite)/polyesterimide resin system has been used as a material for polymer thick-film resistors. The physical and chemical properties of this system as a function of curing temperature were evaluated by means of resistance measurements during the curing process, thermogravimetric analysis, adhesion measurements and scanning electron microscopy examinations. The temperature range between 250 and 300 C has been chosen as the most suitable. The basic electrical properties and the resistance stability to low and high temperature shocks and humidity exposure have been evaluated in relation to the conductive filler used in the ink.     

碳纳米管冷阴极超高真空鞍场规的电场模拟与实验研究

在静电鞍场规的基础上研制了一种碳纳米管(CNT)冷阴极鞍场规(SFG).这种冷阴极鞍场规具有电极尺寸小,吸放气率低,热效应低,功耗低的特点.本文首先计算了碳纳米管冷阴极鞍场规的电场分布,计算结果表明,二极型碳纳米管电子枪的引出栅极的正电位在低于100 V的情况下对环形阳极鞍场规的轴向电位分布影响很少;并且在现有条件下对规管参数进行了测试,实验测定的规管对空气的灵敏度是1.05 Pa-1,规管功耗由热阴极规的0.9瓦减小到7毫瓦.     

Tribological properties of solid lubricants filled glass fiber reinforced polyamide 6 composites

The main purpose of this paper is to further optimize the tribological properties of the glass fiber reinforced PA6 (GF/PA6,15/85 by weight) for high performance friction materials using single or combinative solid lubricants such as Polytetrafluroethylene (PTFE), ultra-high molecular weight polyethylene (UHMWPE) and the combination of both of them. Various polymer blends, where GF/PA6 acts as the polymer matrix and solid lubricants as the dispersed phase were prepared by injection molding. The tribological properties of these materials and the synergism as a result of the incorporation of both PTFE and UHMWPE were investigated. The results showed that, at a load of 40 N and a velocity of 200 rpm, PTFE was effective in improving the tribological capabilities of matrix material. On the contrary, UHMWPE was not conductive to maintain the structure integrity of GF/PA6 composite and harmful to the friction and wear properties. The combination of PTFE and UHMWPE showed synergism on further reducing the friction coefficient of the composites filled with either PTFE or UHMWPE only. Effects of load and velocity on tribological behavior were also discussed. To further understand the wear mechanism, the worn surfaces were examined by scanning electron microscopy.