图形电镀夹膜修理方法

图形电镀已经是PCB制造加厚铜的主要方式,夹膜问题是此工艺流程的一大顽疾,本文为各位同仁介绍一种有效、简便、实用的修理夹膜的方法.     

Good conductivity of a single component polydiacetylene film

Two films were prepared from single component monomer solutions. In these monomers, diacetylene and two acid groups are licked by flexible side chains. The side chain serves as the spacer between diacetylenes. After UV-irradiation, monomer films were transformed to polydiacetylene films and one of films exhibited conductivity drastically increases. This conductivity is two orders of magnitude greater than the conductivity value of reported nondoped polydiacetylene films.     

茂金属聚乙烯产品表征、膜性能及应用

通过介绍茂金属聚乙烯产品的表征结果,说明了茂金属聚乙烯产品与齐格勒-纳塔催化聚乙烯产品相比具有独特分子量分布和分子组成分布,进而解释了茂金属聚乙烯膜制品所具有的基本性能,并介绍了茂金属聚乙烯产品的典型应用。     

Research on cooling effectiveness in stepped slot film cooling vane

As one of the most important developments in air cooling technology for hot parts of the aero-engine,film cooling technology has been widely used.Film cooling hole structure exists mainly in areas that have high temperature,uneven cooling effectiveness issues when in actual use.The first stage turbine vanes of the aero-engine consume the largest portion of cooling air,thereby the research on reducing the amount of cooling air has the greatest potential.A new stepped slot film cooling vane with a high cooling effectiveness and a high cooling uniformity was researched initially.Through numerical methods,the affecting factors of the cooling effectiveness of a vane with the stepped slot film cooling structure were researched.This paper focuses on the cooling effectiveness and the pressure loss in different blowing ratio conditions,then the most reasonable and scientific structure parameter can be obtained by analyzing the results.The results show that 1.0 mm is the optimum slot width and 10.0 is the most reasonable blowing ratio.Under this condition,the vane achieved the best cooling result and the highest cooling effectiveness,and also retained a low pressure loss.     

Rate controlling reactions for copper corrosion in anaerobic aqueous sulphide solutions

Abstract

The long term corrosion behaviour of copper in anoxic aqueous sulphide solutions has been studied using corrosion potential and electrochemical impedance spectroscopy measurements and scanning electron microscopy on corroded surfaces and cross-sections of surfaces prepared using a focused ion beam. Experiments were conducted in solutions containing either 5×10^?4 or 5×10^?5 mol L^?1 sulphide for 1691 and 4000 h respectively. In the more concentrated solution, a coherent, compact and crystalline chalcocite (Cu₂S) film accumulated on the corroding copper surface. A parabolic growth law was obtained, and the kinetics were controlled by Cu(I) ion transport either through the Cu₂S matrix or along crystalline grain boundaries in the film. In the more dilute solution, the growth of a less crystalline, porous chalcocite layer followed approximately the linear growth kinetics controlled by sulphide ion transport through the pores. If the sulphide was allowed to deplete in the dilute solution, rate control switched to sulphide diffusion in the bulk solution. The implications for waste container corrosion in a nuclear waste repository are discussed.     

Comparative study on microstructures and mechanical properties of the heat-treated Al–5.0Cu–0.6Mn–xFe alloys prepared by gravity die casting and squeeze casting

The Al–5.0 wt% Cu–0.6 wt% Mn alloys with different Fe contents were prepared by gravity die casting and squeeze casting. The difference in microstructures and mechanical properties of the T5 heat-treated alloys was examined by tensile test, optical microscopy, deep etching technique, scanning electron microscope and electron probe micro-analyzer. The results show that both β-Fe and α (CuFe) are observed in T5 heat-treated gravity die cast alloy and only α (CuFe) appears in the squeeze cast alloy when the Fe content is 0.5 wt%. When the Fe content is more than 1.0 wt%, the main Fe-rich intermetallics is α (CuFe) in both squeeze cast and gravity die cast alloys. The mechanical properties of both the gravity die cast and squeeze cast alloys decrease gradually with the increase of Fe content due to the decreased volume fraction of precipitation particles, the increased volume fraction of Fe-rich intermetallics and the increased size of α (Al) dendrites. The squeeze cast alloys with different Fe contents have superior mechanical properties compared to the gravity die cast alloys, which is mainly attributed to the reduction of porosity and refinement of Fe-rich intermetallics and α (Al) dendrite. In particularly, the elongation of the squeeze cast alloys is less sensitive to the Fe content than that of the gravity die cast alloys. An elongation level of 13.7% is obtained in squeeze cast alloy even when the Fe content is as high as 1.5%, while that of the gravity die cast alloy is only 5.3%.     

Effect of relative humidity on the store stability of spray-dried beta-carotene nanoemulsions

In order to overcome the limitations of liquid-base emulsion system, beta-carotene nanoemulsions stabilized by modified starch were spray-dried to powders after the emulsification process. The powders showed a good dissolution in water and the reconstituted emulsions had similar particle sizes with the fresh nanoemulsions. A 30 days storage test was carried out to investigate the effect of relative humility (RH) on the storage stability of beta-carotene powders at 25.0 °C. The beta-carotene degradation profiles over time were found to fit well with a Weibull model and also closely related to the film property of the matrix, moisture sorption property and glass transition temperature of the powder. The results showed that modified starches with lower film oxygen permeability had a higher retention of beta-carotene during storage. The glass transition temperature of powder in different RH also affected the rate of beta-carotene degradation. Overall these results provide useful information for choosing wall materials and storage conditions to protect nutraceuticals in delivery systems.     

面向自适应控制的油膜厚度动力学建模与分析

实现数控机床自适应控制的前提条件是有相关的动力学模型。建立带有载荷、温度等非线性因素的油膜厚度动力学模型是实现重型精密数控机床垂直位移自适应控制的关键。针对没有适用于静压导轨油膜厚度的自适应控制模型,基于Navier-Stokes方程,提出了静压导轨油膜厚度的非线性动力学模型及其简化模型,两者都可用于自适应控制。该模型能体现导轨承受负载变化与油膜厚度变化关系,并包含油膜厚度变化的速度和加速度项,适用于精密液体静压数控设备。经过Simulink tools工具仿真模拟,精度达到10~(-4)的数量级,验证了非线性模型和近似模型的准确性。     

一种基于热弹流润滑理论的组合式密封件密封性能评估模型

介绍了用于评估一种由O形圈和PTFE条组成的组合式密封件密封性能的数学模型.为了更好地模拟真实的工况,该模型综合考虑了许多可能的影响因素,如压力,温度,以及密封件材料性能等.这个模型以弹流润滑理论为基础,可用于计算润滑油膜厚度,压力分布和温度场分布,从而为解决“如何以最小的泄漏率保证较好的润滑性能”这个问题提供理论依据.     

非金属滑靴式柱塞泵润滑特性研究

滑靴副是柱塞泵中的关键摩擦副之一,它们之间的油膜润滑特性制约着柱塞泵的寿命。文中以某型柱塞泵为例,对无源油膜润滑理论进行研究,得出某型柱塞泵在不同状态下的油膜厚度;并结合非金属材料润滑特性,得出非金属材料滑靴与无源油膜润滑理论相结合时滑靴副的润滑特性。根据理论分析及实际应用情况,非金属材料滑靴及无源油膜润滑理论可以应用至其它柱塞泵上。