Parylene镀层对烧结Nd-Fe-B磁体稳定性的影响

采用化学气相沉积法(CVDP)在Nd-Fe-B磁体和电镀Cu层的Nd-Fe-B磁体表面包覆派瑞林(Parylene)镀层，分析Parylene镀层和Parylene+电镀Cu复合镀层对磁体化学稳定性和温度稳定性的影响。Parylene分子沉积到磁体表面形成一层致密的镀层，镀层表面形成大小不同的颗粒，造成磁体表面粗糙度变大。Parylene镀层与Nd-Fe-B基体结合紧密，未出现缝隙和镀层脱落现象，镀层厚度随Parylene粉末质量增加逐渐增大。Parylene镀层一方面可以有效改善Nd-Fe-B磁体的化学稳定性，提高磁体中性盐雾耐腐蚀性能；另一方面对磁体有很好的抗热氧化保护作用，有利于提高磁体的温度稳定性，降低高温磁通不可逆损失(hirr)。Cu镀层的存在不利于Parylene镀层改善磁体化学稳定性和温度稳定性，这是由于电镀Cu层与Nd-Fe-B磁体基体和Parylene镀层结合不紧密，界面存在缝隙与裂痕。     

制备条件对ScYSZ薄膜形貌的影响及其生长模型

采用溶液旋涂法在石英基体上制备了氧化钇氧化钪共稳定氧化锆(ScYSZ)阻挡层薄膜，对前驱体的热分解过程进行了分析，并研究了基体温度和热处理温度对薄膜形貌的影响，在此基础上揭示了前驱体溶液结晶形核生长的过程。结果表明：前驱体在580℃完全分解。不同温度基体上薄膜的表面形貌表明，降低基体温度有利于晶体形核生长。薄膜经不同温度热处理后的表面形貌显示，热处理促进晶体生长与再结晶。在氧化钆掺杂氧化铈(GDC)电解质基体上制备了致密的ScYSZ薄膜，证实了晶体形核生长的规律。     

铜膜在各种介质中的生长规律

综述了铜触头在不同介质中表面薄膜厚度与温度、时间的关系,介绍了有关计算公式、试验曲线及试验方法,计算了铜触头在不同温度、不同介质中表面薄膜厚度与工作时间的关系,并求出薄膜生长速度。     

高温下纳米氧化石墨烯/环氧树脂复合材料的载流子特性

采用原位还原法制备了不同的氧化石墨烯/环氧树脂复合材料试样,对复合材料的微观结构及官能团进行了表征,测量了其玻璃化转变温度和宽频介电谱。微观结构分析表明,单层氧化石墨烯与环氧基体结合较好,而多层氧化石墨烯与环氧基体结合较差,导致多层氧化石墨烯/环氧复合材料的玻璃化转变温度下降明显。利用复交流电导率和模量形式,分析了不同温度下复合材料电荷载流子的特性。当温度高于复合材料的玻璃化转变温度时,其直流电导率随温度的变化关系均符合Vogel-Fulcher-Tammann模型;环氧、单层氧化石墨烯/环氧树脂复合材料在高于其玻璃化转变温度时的直流电导主要是电子跳跃电导,其活化能分别为0.58 eV和0.68 eV;而多层氧化石墨烯/环氧树脂复合材料在温度处于120～150℃之间时,其直流电导主要是电子跳跃电导,活化能为0.98 eV,在160℃以上开始出现离子跳跃电导,活化能为0.32 eV。     

铝合金一步法镀铜工艺研究

铝及其合金上电镀金属比在大多数其他金属基体上电镀更为困难。这是因为铝及其合金对氧具有高度亲和力。新鲜的铝暴露于空气中,表面立即生成一层妨碍基体与镀层牢固结合的氧化膜;铝的电极电位较负,易失去电子,在镀液中易产生接触镀层,也会影响镀层与基体的结合力;铝的热膨胀系数与大多数镀层金属的热膨胀系数相差大而易破坏     

直流继电器电寿命试验中复合触头的温度场和热应力仿真研究

在较大负载等级下,复合触头的结合强度会由于温度和热应力的影响发生变化,甚至导致氧化物层脱落而失效。以典型的AgSnO2In2O3/Cu复合触头为研究对象,基于有限元思想提出一种电器多个动作周期后的温度、热应力仿真计算方法,从而得到复合触头在电寿命试验中的温度场、热应力分布的变化规律,又进一步研究了大负载情况下,复合触头的结合强度、银氧化层厚度等因素对其寿命的影响规律,并通过与试验结果对比验证了仿真模型的正确性。     

机械研磨对陶瓷涂层结合强度的影响

为了探讨电站锅炉用陶瓷涂料涂层结合强度与研磨时间的关系,进行了纯基料和非纯基料研磨时间与涂层结合强度试验。试验结果表明: (1) 涂层结合强度与粉体研磨时间有关,球磨3 h 后,涂层的抗高温氧化性能和涂层与基体的结合强度均有明显提高。(2) 在相同研磨时间情况下,纯基料比非纯基料(基料中添加其他材料) 的涂层结合强度高。(3) 球磨后的粉体长时间放置,涂层结合强度会降低。原因是粉体经机械球磨后,粉体粒子微细化,表面积迅速增大,各相的活性和表面能增加,涂层结合强度提高。长时间放置后,粉体团聚成块状物,表面积、化学活性减少,涂层结合强度降低。     

铝上镀铜镀银工艺

研制以铝代银的熔体和以铝代铜作导电连接板的铝快速熔断器,对节约大量的贵金属和有色金属意义很大。随着材料的改变,表面处理也要改变,我们对在铝上进行无氰镀铜和无氰镀银作了探讨,在现有资料很少的情况下,经过一年的小型试验,现将铝上无氰镀铜和无氰镀银的实验情况介绍如下。一、铝上电镀的关键铝是活泼金属,在周期表中属第Ⅲ周期第Ⅲ类。由于铝有高度的电子亲和力,所以铝表面的氧化膜刚一清除后,很迅速地又形成新的氧化膜,这就影响了导电性能,也给电镀工艺带来较大的困难。氧化膜的存在会直接影响镀层和基体的结合力。铝在酸碱性溶液中都不稳定,此外铝的膨胀系数与大多数金属相差很大,直接影响镀层和基体附着     

钼铜真空开关触头材料渗铜工艺的优化

采用粉末冶金法压制、烧结和熔渗工艺制备钼铜真空开关触头材料,时而会出现钼基体表面氧化黄斑点和渗铜分布不均或钼晶粒间铜相填充不均现象。为了提高钼渗铜工艺效果,在常规钼渗铜工艺基础上,低温熔渗增加一段还原温度、时间梯度段。结果表明,通过优化改进钼渗铜工艺后,钼铜触头产品质量得到了有效控制。     

某些金属元素对Ag-Sn合金内氧化速度的影响

在0.4～ 0.6MPa氧压力、500℃和700℃下研究了某些金属元素对Ag-Sn合金内氧化速度的影响，还用SEM研究了Ag-6.5Sn-1.1Bi-0.6Cu合金内氧化层的微观结构，结果表明：氧化层厚度与时间成抛物线关系，添加金属元素对Ag-Sn合金的内氧化速度有明显的影响，易氧化的金属元素能加速Ag-Sn合金内氧化。氧化物以微细颗粒分布的银基体中，发现在晶界处有部分氧化物聚集，并且有2～5μm以某种氧化物为主的细小颗粒。     

解决薄膜绕包线导体发黑方法的研究

采用导体表面加涂保护膜的方法来隔绝氧气.达到阻止导体氧化的目的.比较7几种保护剂,分析了薄膜绕包线导体出现发黑现象的原因,提出了有效的解决方法,验证了产品的性能.结果表明,该保护膜对产品的力学及电气性能无影响.     

Copper Compatible Barium Titanate Thin Films for Embedded Passives

Barium titanate thin films have been prepared by chemical solution deposition on 18 m thick, industry standard copper foils in the absence of chemical barrier layers. The final embodiment exhibits randomly oriented BaTiO₃ grains with diameters between 0.1 and 0.3 m, and an equiaxed morphology. The average film thickness is 0.6 m and the microstructure is free from secondary or interfacial phases. The BaTiO₃ films are sintered in a high temperature reductive atmosphere such that copper oxidation is avoided. Subsequent lower-temperature, higher oxygen pressure anneals are used to minimize oxygen point defects. Permittivities of 2500 are observed at zero bias and room temperature, with permittivities greater than 3000 at the coercive field. Loss tangents under 1.5% are demonstrated at high fields. The BaTiO₃ phase exhibits pronounced ferroelectric switching and coercive field values near 10 kV/cm. Temperature dependent measurements indicate a ferroelectric transition near 100C with very diffuse character. Combining the approaches of the multilayer capacitor industry with traditional solution processed thin films has allowed pure barium titanate to be integrated with copper. The high sintering temperature—as compared to typical film processing—provides for large grained films and properties consistent with well-prepared ceramics. Integrating BaTiO₃ films on copper foil represents an important step towards high capacitance density embedded passive components and elimination of economic constraints imparted by traditional noble metallization.     

Chemical, Physical and Electrical Properties of Aged Dodecylbenzene 2: Thermal Ageing of Single Isomers in Air

The linear isomer of dodecylbenzene (DDB), 1-phenyldodecane, was aged at temperatures of 105 and 135 °C in air and the resultant products were analyzed using a range of analytical techniques. On ageing, the 1-phenyldodecane darkened, the acid number, dielectric loss and water content increased and significant oxidation peaks were detected in the infrared spectrum. When aged in the presence of copper, a characteristic peak at 680 nm was also detected by UV/visible spectroscopy but, compared with previous studies of a cable-grade DDB, the strength of this peak was much increased and no appreciable precipitate formation occurred. At the same time, very high values of dielectric loss were recorded. On ageing in the absence of copper, an unusually strong infrared carbonyl band was seen, which correlates well with the detection of dodecanophenone by gas chromatography / mass spectrometry and nuclear magnetic resonance spectroscopy. It was therefore concluded that the ageing process proceeds via the initial production of aromatic ketones, which may then be further oxidized to carboxylic acids. In the presence of copper, these oxidation products are present in lower quantities, most of these oxidation products being combined with the copper present in the oil to give copper carboxylates. The behavior is described in terms of a complex autoxidation mechanism, in which copper acts as both an oxidizing and a reducing agent, depending on its oxidation state and, in particular, promotes elimination via the oxidation of intermediate alkyl radical species to carbocations.     

带电设备无线视频探查装置的研发及应用

为改善钢芯铝绞线与设备的连接,电力系统一般使用经过特殊工艺处理焊接而成的铜铝过渡接头,因工艺水平及现场作业条件限制,运行过程因氧化、发热等原因会使接触电阻增加,氧化面积扩大,最终导致铜铝过渡接头发生强度下降而断裂.针对铜铝过渡接头常处于高空且为带电状态,目测及红外热像检查存在较大局限性的问题,提出带电设备无线视频探查方...     

如何降低电线电缆生产过程中铜导体氧化变色

根据铜的化学性质,采用物理方法阻隔铜与空气的接触,用抗氧剂钝化膜阻隔铜导体氧化,绝缘使用过氧化物交联剂,保持铜导体处于被还原状态,用阴极保护避免铜导体氧化等,能够降低电线电缆生产过程中铜导体氧化变色.     

内氧化法制备Al2O3/Cu复合材料的性能研究

采用Cu2O粉为供氧方式的内氧化法制备Al2O3／Cu复合材料。通过微观组织观察，分析了Al2O3／Cu复合材料的组织，研究了复合材料的导电性能及高温下退火后的硬度特性。研究表明，细小的Al2O3颗粒在Cu基体内的弥散分布，阻碍了位错及晶界、亚晶界运动，抑制了再结晶，从而使制备的Al2O3／Cu复合材料电导性能好，而且高温退火后仍保持较高的硬度。     

Influence of thermal and UV aging on electroluminescence ofpolypropylene films

Polymer aging appears to be an important factor which affects the electroluminescence of polyolefins subjected to a homogeneous AC field. We investigate the influence on electroluminescence emission of thermal and UV aging of commercial polypropylene films for capacitor application. Chemical and morphological changes of the materials are studied as function of aging conditions. Correlation is found between material oxidation and electroluminescence. Oxidation reduces the level of electroluminescence but does not change the spectral distribution of the light, thereby indicating that the luminescence centers are not the carbonyl groups     

Chemical, Physical and Electrical Properties of Aged Dodecylbenzene: Thermal Ageing of Mixed Isomers in Air

A commercial dodecylbenzene (DDB) cable oil was aged at temperatures between 90 and 135degC in air and was analyzed using various analytical techniques including optical and infra-red spectroscopy and dielectric analysis. On ageing, the oil darkened, significant oxidation features were found by infra-red spectroscopy and the acid number, water content and dielectric loss all increased. Ageing in the presence of paper or aluminum did not affect the ageing process, whereas ageing was significantly modified by the presence of copper. An absorption at 680 nm ("red absorbers") was detected by ultra-violet/visible spectroscopy followed by the production of an opaque precipitate. A reaction between copper and the acid generated on ageing is thought to produce copper carboxylates, and X-ray fluorescence confirmed that copper was indeed present in both the aged oil and the precipitate. Significantly, once red absorbers were detected, the dielectric loss increased to catastrophically high values and, therefore, the appearance of these compounds may serve as a useful diagnostic indicator. The development of acidity on ageing appears to be key in initiating the destructive copper conversion reaction and hence the control of oil acidity may be key to prolonging the life of DDB cable oils.     

锂离子电池电极表面的研究进展

锂离子电池电极表面膜的形成、结构和组成与电池性能有很大的关系.综述了近年来电极表面化学研究的进展,阐述了电极表面膜的形成、结构和组成与电解液的关系,并对表面膜的导电机理和电解液的氧化模型进行了分析和讨论.