纳米银-聚合物薄膜的制备及力电性能测试

聚合物基底上纳米银颗粒薄膜的制备工艺相对简单,成本较低,且该薄膜具有成为高敏感性压阻应力/应变传感材料的潜力。本文采用银镜制备法在聚酰亚胺(PI)和聚乙烯(PE)上合成了纳米银颗粒薄膜,系统研究了该薄膜制备工艺、结构特性、材料性能之间的关系。实验考察了材料“浸泡”时间及聚合物材料前处理等因素对材料表面吸附纳米颗粒含量的影响,研究了 “浸泡”时间对纳米银颗粒粒径大小、颗粒含量及分布的影响,并探讨了不同聚合物基体的颗粒特性对薄膜二维导电渗滤,压阻特性及拉伸性能的影响。研究表明,增加“浸泡”时间能够增加纳米银颗粒粒径大小,提高银颗粒的含量及分布均匀性；在相同的制备条件下,PI基底较PE基底对纳米银颗粒具有更加优异的吸附效果；在PI 和PE基底上的纳米银颗粒薄膜均表现出显著的压阻性能,且电阻对应变的敏感性随应变的增大及银颗粒含量的减少而显著提高。     

PVDF压电薄膜的应变传感特性研究

PVDF压电薄膜是一种重要的智能材料。本文理论分析了智能材料——PVDF压电薄膜的应变传感机理；研究了PVDF应变传感器的制作与布设工艺；试验研究了PVDF传感元件在准静态和动态响应下的传感特性．得到了PVDF传感元件的电压灵敏度，并分析了PVDF压电薄膜的尺寸对灵敏度的影响。研究结果表明：PVDF传感器具有灵敏度高、线性度好、制作与布置工艺简单、面监测等优点．适用于土木工程结构的健康监测。     

TPU/MWNTs定向纳米纤维制备及压阻特性研究

利用静电纺丝技术制备了热塑性聚氨酯/多壁碳纳米管(TPU/MWNTs)复合纳米纤维,并通过平行板接收装置实现纤维的定向排布。测试了纤维压阻敏感性随MWNTs含量的变化规律,与浇注法制备的TPU/MWNTs膜的压阻敏感性进行对比分析,结果表明MWNTs含量仅为2.91%(质量分数)时,纤维就表现出了最佳的压阻特性(Gauge factor≈11.4),比同质量分数下膜的压阻特性(Gauge factor≈2.6)有较大的提高,同时在8%的拉伸应变内电阻的相对变化量与应变值维持良好的线性关系,线性度优于复合膜。     

高温ITO薄膜应变计制备及压阻性能EI北大核心CSCD

高温薄膜应变计被广泛应用于极端条件热端构件的应变测量。ITO薄膜应变计通常能够应用于1000℃以上的应变测量,为了研究ITO薄膜的显微结构、XPS光谱、阻温特性及压阻响应,采用磁控溅射在陶瓷基底上制备了ITO薄膜应变计,并在高温纯N2中热处理ITO薄膜。结果表明,其电阻温度系数稳定在-750×10-6℃-1,在1200℃下测试其应变特性,测得电阻漂移率为0.0018 h-1,应变因子为16。ITO薄膜在高温下具有稳定的电阻温度系数和低漂移率,为高温端部件应变的测量提供了可能。     

柔性纳米复合材料压阻式应变传感器的研究进展

柔性纳米复合材料,由于其优异的传感性能、良好的延展性,在压阻式应变传感器方面,受到研究者们不断的关注,主要应用于智能可穿戴,结构健康监测等领域.本文主要从结构设计、制备方法、应用前景三方面,综述了近年来国内外对复合材料压阻式应变传感器在材料选取及结构设计下传感器性能的研究成果及研究进展.首先分析了压阻式传感器的性能参数...     

空间飞行器用薄膜温度/应变传感技术研究

随着功能薄膜制备方法及微细加工技术的日益成熟，基于各类薄膜敏感元件的薄膜传感技术蓬勃发展。薄膜传感器件尺寸小、集成度高、灵敏度高，在深空探测、空间飞行器结构健康监测、载人航天等领域展现出广阔的应用前景。针对空间飞行器的各类传感需求，对低温/高温温度传感、热流传感、高温应变传感、柔性大应变传感、柔性智能蒙皮等应用中薄膜传感材料和器件的关键技术及国内外研究现状进行了综述，并对薄膜传感技术的未来发展进行了展望。     

磁控溅射制备镍薄膜热阻温度传感器工艺研究

利用镍薄膜的温度电阻特性以及磁控溅射镀膜技术设计并制备了薄膜热阻型温度传感器，为了达到较好的工作稳定性，设计了多层的复合膜系。文中分析了沉积薄膜的工作压力、电源功率、靶基距、退火温度、退火时间等制备工艺参数对热阻薄膜特性的影响，以及工艺参数对所沉积的镍薄膜的膜厚均匀度和温度电阻曲线，温度电阻系数等传感特性的影响。通过调整实验的工艺参数，最终得到电阻温度性能较好的镍薄膜温度传感器。测试结果表明薄膜传感器在0-250℃之间温度电阻曲线有较好的线性度和稳定性。     

直流磁控溅射制备SnO2薄膜的阻变特性研究

采用直流磁控溅射法在Pt/Ti/SiO2基片上分别以三种不同的基板温度和后热处理工艺制备了二氧化锡(SnO2)薄膜。采用X射线衍射仪对三种薄膜的晶格结构进行了分析表征,通过Keithley 4200半导体参数分析仪对薄膜的阻变特性进行了测试。实验结果表明:三种制备条件下的SnO2薄膜均具有阻变性能,基板温度350℃和850℃退火处理分别制备的薄膜同时具有良好的写入/擦除电压分布一致性、较好的高阻态阻值离散性和较大的开关比。初步讨论了三种薄膜阻变特性的机理,薄膜内部导电细丝的形成和断裂程度不同造成三种薄膜高低阻态电阻分布不同,同时影响了写入与擦除阈值电压的分布一致性等阻变参数。     

超声雾化热分解气相沉积法制备TiO_2薄膜的气敏特性研究

运用超声雾化热分解法制备了纯TiO2薄膜,并通过超声雾化分解和电子束蒸发两种方法注入了Ru,Rh,Ir杂质,研究了各种薄膜对O2的传感特性,并利用透射电镱和原子力显微镜分析薄膜晶体的微观结构。实验发现,纯TiO2薄膜在高工作温度(400℃)下对O2的传感性也较弱,而通过超声雾化分解法制备的掺杂TiO2薄膜工作温度明显降低到300℃,传感灵敏度极大提高,响应时间缩短,并且超声雾化分解法制备比电子束蒸发注入的传感薄膜具有更好的气敏传感特性。     

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%/℃。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.