改性苯乙烯-丙烯酸酯防水防油剂的研究

以甲基丙烯酸十二氟庚酯(FM)、丙烯酸丁酯(BA)、苯乙烯(St)、甲基丙烯酰氧乙基三甲基氯化铵(DAC)、丙烯酸十八酯(ODA)为原料,采用无皂乳液聚合,制得了阳离子含氟丙烯酸酯多元共聚物乳液,并对聚合物的结构、组成进行了表征,研究了引发剂、FM的用量对乳液耐水性和稳定性的影响。单独使用含氟乳液对纤维类织物进行表面涂敷,水和油滴在织物上所成的接触角最大可分别达到135°和87°,同时织物的抗张强度、耐折度、平滑度分别提高13.45%、15.38%和60.52%。     

Application of the surface free energy concept in polymer processing

The surface characteristics of variously treated carbon and glass fibres have been determined by contact angle measurements (using a capillary rise technique), inverse gas chromatography, and zeta potential measurements. The contact angles of water and methylene iodide were used to calculate the dispersive and non-dispersive components of the fibre surface free energy by applying the geometric mean approach, and the approach by Fowkes to estimate the acid-base term of the thermodynamic work of adhesion. The results obtained correlate with those of inverse gas chromatographic and zeta potential measurements. The non-polar surface character of the carbon fibre can be altered by oxidizing, or finishing the fibres with an epoxy resin. The acid-base term of the thermodynamic work of adhesion, W^ab _a, and the non-dispersive component of the surface free energy, γ^p _s, are increased drastically by these treatments. Treatment of the 'high-energy' glass fibre surface with an aminosilane results in a relatively low surface free energy with basic surface groups. When epoxy dispersions were used for sizing the glass fibres, the surface free energy increased without changing the basic surface character. A direct correlation between the surface-energetic properties of the fibres and the mechanical behaviour of the fibre-reinforced polyamide composites was not generally found.     

50CrVA钢弹簧断裂分析

由50CrVA钢绕制的弹簧在服役后发生断裂,采用断口宏观及微观观察,金相组织分析,能谱分析,显微硬度试验等方法对断裂原因进行了综合分析。结果表明,断裂弹簧属氢致脆性断裂,在加工过程中电镀时的电接触损伤是发生氢致脆断的主要原因,同时退铜工艺过程中酸洗过度也是导致氢致脆断的因素。提出改进措施为在电镀过程中,确保电极固定后与簧丝不局部接触,在表面处理工艺中尽可能减少弹簧吸氢环节,同时保证除氢的时间受控。该故障的原因分析及纠正措施可为提高产品质量,加强特种工艺控制,防止类似问题再次发生提供借鉴。     

桩-土界面的数值模拟与单桩Q-S曲线的数值分析

回顾和总结了平面接触问题经典无厚度Goodman界面单元法的主导思想,针对竖向受力承载单桩的Q-S曲线数值分析模型给出了一种轴对称等参无厚度界面元,以模拟两者的相互接触界面。利用所建立的桩-土数值模型对一实际工程的大直径承载桩的Q-S实测曲线进行了数值模拟分析和预测,并且利用数值实验技术对不同接触条件下的单桩Q-S曲线特征进行了数值分析,获得了一些有益的结论。     

Molybdenum nitride modified AISI 304 stainless steel bipolar plate for proton exchange membrane fuel cell

A molybdenum nitride diffusion coating has been prepared on the surface of AISI 304 stainless steel (304 SS) by plasma surface diffusion alloying method as bipolar plate for proton exchange membrane fuel cell (PEMFC). X-ray diffraction data shows that the molybdenum nitride is face-centered-cubic Mo₂N phase. The results of scanning electron microscopy in combination with energy-dispersive X-ray analysis spectrometer indicate that the as-prepared molybdenum nitride diffusion coating consists of a ∼3.5 μm surface layer (molybdenum nitride) and a ∼0.5 μm subsurface layer (Mo and N solid solution). In addition, the average contact angle with water for modified 304 SS is 91°, demonstrating the better hydrophobic property of the surface modified 304 SS as compared to the untreated ones with average contact angle of 68°. Potentiodynamic and potentiostatic testing in simulated PEFMC operating conditions (0.05 M H₂SO₄ + 2 ppm F⁻ solution at 70 °C purged with either hydrogen or air) as well as interfacial contact resistance (ICR) measurement imply that the molybdenum nitride modified 304 SS exhibits improved corrosion resistance and promising ICR.     

高温超导变压器及发展现状

介绍高温超导变压器及其优点．并分析高温超导变压器与传统油浸变压器的区别，对高温超导变压器的发展现状进行总结，其中着重介绍在变压器应用中高温超导线材的性能参数和高温超导变压器的性能参数。探讨高温超导变压器的应用前景。     

On the Role of Contact Resistance and Electrode Modification in Organic Electrochemical Transistors

Contact resistance is renowned for its unfavorable impact on transistor performance. Despite its notoriety, the nature of contact resistance in organic electrochemical transistors (OECTs) remains unclear. Here, by investigating the role of contact resistance in n‐type OECTs, the first demonstration of source/drain‐electrode surface modification for achieving state‐of‐the‐art n‐type OECTs is reported. Specifically, thiol‐based self‐assembled monolayers (SAMs), 4‐methylbenzenethiol (MBT) and pentafluorobenzenethiol (PFBT), are used to investigate contact resistance in n‐type accumulation‐mode OECTs made from the hydrophilic copolymer P‐90, where the deliberate functionalization of the gold source/drain electrodes decreases and increases the energetic mismatch at the electrode/semiconductor interface, respectively. Although MBT treatment is found to increase the transconductance three‐fold, contact resistance is not found to be the dominant factor governing OECT performance. Additional morphology and surface energy investigations show that increased performance comes from SAM‐enhanced source/drain electrode surface energy, which improves wetting, semiconductor/metal interface quality, and semiconductor morphology at the electrode and channel. Overall, contact resistance in n‐type OECTs is investigated, whilst identifying source/drain electrode treatment as a useful device engineering strategy for achieving state of the art n‐type OECTs.     

Effect of Starvation on Traction and Film Thickness in Thermo-EHL Line Contacts with Shear-Thinning Lubricants

The effect of starvation on traction and film thickness behavior in thermo-EHL rolling/sliding line contacts has been studied using full EHL simulations. The simulations employed the free volume equation for viscosity–pressure–temperature relationship and Carreau viscosity model to describe the shear-thinning behavior of the EHL lubricant. The simulation results were used to develop equations for estimating the factors by which the traction coefficient increases and film thickness decreases as a function of the degree of starvation. For the situations involving inadequate lubricant supply at the inlet, these factors can be used to correct the traction coefficient and central film thickness predicted with the assumption of fully flooded condition.     

水解酸化/生物接触氧化/沉淀工艺处理牛仔衣染色废水

针对牛仔衣染色(以靛蓝染料为主)废水色度较高、有毒性及污染严重的特点,确定采用水解酸化/生物接触氧化/沉淀的工艺处理该废水.在丽发制衣厂的应用实践表明:该工艺切实可行,运行费用低,处理效果稳定,出水水质达到DB 44/26-2001中一级排放标准,COD、BOD5、SS、色度去除率分别达到94%、92%、87%、83%.     

埋藏式钢岔管与外围结构的联合作用分析

为了更深入地了解埋藏式岔管与外围结构联合承载的力学机理,采用三维有限元法对岔管与外围结构联合作用做了精细的力学仿真。尝试了一种新的模型,即设置回填混凝土网格,模拟钢岔管、混凝土、围岩三者之间的两道缝隙及其力学接触行为,考虑混凝土承载后的塑性变形特征。结果表明,岔管与外围结构在空间中的相互作用过程复杂:由于岔管与外围结构联合承载,使钢材强度得到了充分的发挥;回填混凝土未沿径向均匀开裂,基于此假定的力学模型值得商榷;回填混凝土变形应被充分重视,有些部位的压缩变形甚至大于结构间原始缝宽,不利于联合承载;两道缝模式得出的内水压力围岩分担率明显低于一道缝模式,后者可能高估了围岩分担率。研究成果为埋藏式岔管受力分析提供了一种新模式。