静电纺丝PAN纳米纤维的制备与表征

将聚丙烯腈(PAN)粉末配制为PAN/DMF溶液,通过静电纺丝工艺制备了PAN纳米纤维.使用扫描电镜对纤维进行表征,研究了聚合物溶液浓度、静电压和喷射速率对纳米纤维形貌和直径的影响.结果表明:一定范围内减小高聚物溶液浓度、增大静电压、减小喷射速率,可适当减小纤维的直径.X射线衍射谱图分析表明,PAN溶液的浓度对纤维的结...     

齿科用二氧化硅纤维的制备与表征

基于高压静电纺丝技术,用聚乙烯吡咯烷酮(PVP)作模板剂,正硅酸乙酯作硅源,无水乙醇和去离子水作共溶剂,盐酸作催化剂,通过溶胶-凝胶法在不同纺丝电压、接收距离条件下合成了SiO2纤维.利用SEM、XRD、EDS及FTIR等方法对其进行了表征.结果表明:经过焙烧,PVP已完全从SiO2纤维中去除;较高的纺丝电压和较大的接收距离有助于得到形貌较好、直径均匀、表面光滑的SiO2纤维;最佳纺丝电压为25kV,接收距离为18cm.     

荧光介孔粉料掺杂对荧光纳米纤维的形貌及其荧光性质的影响分析

为制备荧光纳米纤维,并研究不同因素对其形貌及其荧光性能的影响,以聚偏氟乙烯为聚合物母体材料,掺杂负载罗丹明B的MCM-41介孔粉料,通过静电纺丝工艺进行制备并研究其性能.由于MCM-41介孔的形貌特征,罗丹明B可在其中有效负载并均匀分散,从而抑制荧光粉的聚集趋势并促进荧光发光.通过调整纺丝液的浓度和静电纺丝工艺参数(如纺丝液进料速度、电压等),细化研究了影响复合荧光纳米纤维形貌及其各项性能的因素,掌握了影响荧光纳米纤维荧光特性的规律,有利于其开发并进行实际应用.     

静电纺丝法制备LaMO3(M=Co,Fe,Mn)纳米纤维及其表征

采用静电纺丝法结合溶胶-凝胶技术制备了钙钛矿型过渡金属氧化物LaMO3(M=Co,Fe,Mn)纳米纤维.并应用热重(TGA)、X射线衍射(XRD)、傅立叶红外变换光谱(FTIR)和扫描电镜(SEM)对所制备的纳米纤维进行了表征.结果表明,焙烧温度对纳米纤维的相结构和形貌有着显著的影响.在600 ℃焙烧2 h后,钙钛矿结...     

海洋平台结构件表面脉冲纳米复合镀层的制备

本实验采用双脉冲电源,在Q235海洋平台结构件表面沉积了纳米复合镀层。通过改变镀液中纳米颗粒浓度、脉冲电源占空比和电镀电源方式,研究了不同条件下制备的复合镀层的微观形貌和组织结构。     

TiO_2@C纳米纤维作为钠离子电池负极材料的研究

二氧化钛作为钠离子电池负极材料是近几年来的一个研究热点,其中锐钛矿型的TiO_2作为负极材料体现出优异的储钠特性。TiO_2是一种常用的半导体材料,自身电导率较低,晶格排列比较紧密,不利于钠离子在电极材料中传输。本文针对TiO_2负极材料低电导率,单一晶型TiO_2钠离子传输慢的问题,采用静电纺丝的方法制备了TiO_2@C纳米纤维,通过控制前驱体烧结温度制备出了混合晶型的TiO_2@C复合材料,得到了性能较为优异的钠离子电池负极材料。     

舰船高温排烟管表面纳米Al2O3-CeO2/Ni镀层的微观组织和抗高温氧化性能

为了制备具有优异抗氧化性能的复合镀层,试验采用双脉冲电源,在舰船高温排烟管试样表面沉积Al2O3-CeO2/Ni纳米复合镀层,通过抗氧化性能测试,研究了Al2O3纳米颗粒浓度和CeO2浓度对复合镀层的抗氧化性的影响。试验得出复合镀层的微观组织随着Al2O3颗粒的添加细化晶粒,当镀液中纳米CeO2颗粒浓度增加到1.5 g/L时,晶粒尺寸分布均匀,同时镀层表面平整、致密;复合镀层的抗氧化性随镀液中纳米Al2O3浓度增加而增加,随CeO2浓度的增加先降低后增加。     

海洋工程用铝合金表面微弧氧化膜的耐腐蚀性能

为了制备性能良好的微弧氧化膜层,以提高海洋平台用2Al2铝合金的耐磨性和耐腐蚀性。本实验采用微弧氧化技术,将不同浓度的MoS2颗粒（0 g/L、1 g/L、2 g/L、4 g/L、6 g/L和8 g/L）添加到电解液中,在2Al2铝合金表面制备微弧氧化膜层。通过扫描电子显微镜和光学显微镜对复合镀层的微观形貌、组织结构进行分析;采用摩擦磨损试验、电化学腐蚀试验等实验方法分析了镀层的耐磨性和耐腐蚀性能。实验结果表明,随着纳米MoS2颗粒含量的增加,陶瓷层表面微孔尺寸减小,微孔数量增加,并且孔洞的分布更加均匀,致密度得到了很大的提高,且膜层厚度随着纳米MoS2颗粒含量的增加先增后减;添加纳米MoS2颗粒后,使得膜层摩擦系数降低,并且基本稳定在0.45左右;当纳米MoS2颗粒含量为4g/L时,陶瓷层的耐腐蚀性能最好。     

油船油气回收用中空纤维陶瓷膜的制备

膜分离技术已经在不同的领域内得到了广泛的应用,本实验主要目的是制备出符合油气回收用的中空纤维陶瓷膜.本实验是利用相转化法将铸模液纺制成中空纤维膜的,纺制出的中空纤维膜经过一定的处理后放入箱式电阻炉中按照一定的温度曲线进行高温烧结,成功制得内径811.49μm和壁厚115.19μm的中空纤维陶瓷膜.所制得的中空纤维陶瓷膜具有良好的耐酸碱性并且抗拉强度也提高到烧结之前的70多倍,能够满足不同工作环境条件的要求,另外所制得的中空纤维陶瓷膜较烧结之前具有更多的孔隙,有很好的通透性能.     

采用超低频电流场实现深水UUV遥控

首先分析遥控UUV的通信方式,将采用水下电流场通信和水声通信进行比较,得出采用水下电流场实现深水UUV遥控的优越性。分析水下电流场通信的原理,给出深水UUV接收遥控信号电压的表达式,总结出影响水下通信距离的关键参数。研究UUV接收信号随频率、通信距离的变化规律,最后提出增大水下电流场通信距离的方法。     

PVA纤维增强水泥基复合材料的耐久性能

混凝土结构的耐久性是工程领域需要迫切解决的问题之一。PVA（聚乙烯醇）纤维增强水泥基复合材料（PVA—ECC）在水泥基制品开发、桥梁道路施工、结构加固补强等领域有着广阔的应用前景。文中阐述了各种因素对PVA纤维增强水泥基复合材料的耐久性能的影响及目前研究的不足,以进一步研究优化该材料的耐久性能,更好地应用于实际工程。     

天然海水中15CDV6/MDN138及15CDV6/MDN250合金的电流相互作用（英文）

The galvanic corrosion behavior of the metal combinations 15 CDV6/MDN138 and 15 CDV6/MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI's Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250, and 15 CDV6 of the individual metal, the galvanic potential and galvanic current of the couples 15 CDV6/MDN138 and 15 CDV6/MDN250, were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with 15 CDV6 were analyzed using XRD. The electrochemical behavior of MDN138, MDN250, and 15 CDV6 in seawater was studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with 15 CDV6 have been examined with a scanning electron microscope. The results of the study reveal that the galvanic protection offered by15 CDV6 to MDN250 and MDN138 in natural seawater amounts to 93% and 98%, respectively, implying that the galvanic protection offered by 15 CDV6 is continuous and effective, which has been further evinced from the adherent nature of the calcareous deposit film comprising compounds such as CaCO_3(calcite, aragonite, and vaterite), MgCO_3(magnesite),Mg(OH)_2(brucite), and MgO(brucite).     

PVA纤维增强水泥基复合材料基本性能及其工程应用

PVA(聚乙烯醇)纤维增强水泥基复合材料(PVA-ECC)是一种采用水泥、矿物掺合料、水、粒径小于5mm的细骨料与PVA纤维拌和而成的水泥基复合材料。文中阐述了PVA纤维增强水泥基复合材料的基本性能,与普通混凝土相比,其抗压试验中达到峰值荷载后承载力下降缓慢,抗拉和弯曲试验中均显示出应变硬化特性,且具有更好的抗剪承载力和抗剪切变形的能力。纤维增强水泥基复合材料具有优异的延性和耐久性,已成功应用于实际工程。     

天然海水中HE15/MDN138和HE15/MDN250合金的原电池反应（英文）

HE15 is a heat treatable high strength alloy with excellent machinability find wide applications in aerospace and defence industries. In view of their excellent mechanical properties, workability, machinability, heat treatment characteristics and good resistance to general and stress corrosion cracking, MDN138 MDN250 have been widely used in petrochemical, nuclear and aerospace industries. The galvanic corrosion behaviour of the metal combinations HE15/MDN138 and HE15/MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI's Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250 and HE15 of the individual metal, the galvanic potential and galvanic current of the couples HE15/MDN138 and HE15/MDN250 were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with HE15 were analyzed using XRD. The electrochemical behaviors of MDN138, MDN250 and HE15 in seawater have been studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with HE15 have been examined with scanning electron microscope. The results of the study reveal that HE15 offered required amount of protection to MDN138 MDN250.     

Galvanic interactions of HE15 /MDN138 & HE15 /MDN250 alloys in natural seawater

HE15 is a heat treatable high strength alloy with excellent machinability find wide applications in aerospace and defence industries. In view of their excellent mechanical properties, workability, machinability, heat treatment characteristics and good resistance to general and stress corrosion cracking, MDN138 & MDN250 have been widely used in petrochemical, nuclear and aerospace industries. The galvanic corrosion behaviour of the metal combinations HE15 /MDN138 and HE15 /MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI’s Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250 and HE15 of the individual metal, the galvanic potential and galvanic current of the couples HE15 /MDN138 and HE15 /MDN250 were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with HE15 were analyzed using XRD. The electrochemical behaviors of MDN138, MDN250 and HE15 in seawater have been studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with HE15 have been examined with scanning electron microscope. The results of the study reveal that HE15 offered required amount of protection to MDN138 & MDN250.     

船用油污水分离装置现状及发展

国际海协的新决议对舱底油污水处理提出了更高的要求.文章在分析现有分离技术的基础上,介绍了几种满足新决议要求的处理技术.     

Relationships between near-bottom dissolved oxygen and sediment profile camera measures

The United States Environmental Protection Agency (U.S. EPA) and other environmental authorities regulate concentrations of dissolved oxygen (DO) as a measure of nutrient-related eutrophication in estuarine and coastal waters. However, in situ DO concentrations are extremely variable, and their characterization requires an extensive sampling program to provide data over meaningful scales of time and space. In contrast, benthic faunal communities integrate the impacts of low DO over time, and can be rapidly assessed using benthic imaging. The goal of this study was to quantify the relationships between near-bottom dissolved oxygen and measures derived from benthic imaging with a sediment profile camera. We monitored three stations in Narragansett Bay (Rhode Island, USA) for DO and other water quality parameters 15–20 cm above the sediment surface on 15-minute intervals between July and November 2002, and regularly sampled these stations with a sediment profile camera throughout this time period. These soft-sediment stations encompassed several DO environments. We tested for relationships between near-bottom DO and several camera measures, including Nilsson and Rosenberg's Benthic Habitat Quality (BHQ) index, the apparent Redox Potential Discontinuity (aRPD) depth, and various faunal features that can be identified in sediment profile images. Camera measures were examined against a variety of methods of characterizing DO (including mean DO, and the percent of time under various DO thresholds), over a span of time scales from 1 day to 49 days. The best relationship (highest r²) between near-bottom DO and BHQ was found when DO was evaluated as the percent of time under a hypoxic threshold of 2.6 mg l^− 1 over a 28-day time scale (by examining DO records over the 28 days preceding each camera deployment). We found that, over several benthic settings, the BHQ index was successful at identifying environments that had experienced relatively high or low DO over the preceding four weeks. Our sediment profile data showed more variability with DO in the intermediate values of BHQ. We conclude that sediment profile camera measures correlate to DO in areas where low DO is the primary stressor, integrate DO over ecologically relevant time scales, and enable sampling over spatial scales that are meaningful for mapping by virtue of rapid deployment and analysis. We submit that sediment profile camera imagery is a useful assessment and mapping tool for environmental managers interested in benthic condition and in first-order quantitative estimates of near-bottom DO regimes in areas where low DO is the primary benthic stressor.     

潜艇舱室大气环境污染物在线检测技术

由于潜艇舱室存在空间狭小、设备繁多等特点,因此,当潜艇潜航时,其设备运行、材料释放,以及人的活动和新陈代谢均会使舱室内空气中的各种有害气体种类增多、浓度增大,从而危害艇员身体健康。以微型飞行时间质谱为核心检测手段,建立了基于自主设计的微缓冲区膜进样接口,使得二甲苯、甲苯和苯的信号强度比使用毛细管得到的信号强度分别高500,300和160倍。同时,提出了膜进样飞行时间质谱,使得对苯、甲苯和二甲苯的响应时间分别达到了6,10和15 s。此外,基于VUV灯研发了SPI、SPI-CI和SPI-PEI新型电离源。结果显示:利用单光子电离,对苯、甲苯和二甲苯的检出限分别达到了3×10-9,4×10-9和6×10-9,该技术为潜艇舱室内的污染物气体检测提供了一种有效手段。     

氯离子侵蚀下混合纤维增强钢筋混凝土损伤规律

混合纤维增韧混凝土具有很好的耐久性。针对PVA和UPE混合纤维混凝土,采用高浓度氯离子溶液进行120 d侵蚀试验,并结合三维数值模拟技术,预测分析氯离子侵蚀前后钢筋混凝土梁的承载力和损伤变化规律。结果表明,无纤维混凝土和纤维体积含量为0.2%(其中0.1%PVA和0.1%UPE)的混凝土受海水侵蚀后脆性增加,峰值应力和对应的应变减小;但掺加纤维能降低混凝土梁遭受氯离子侵蚀的抗弯曲承载能力的损失率和峰值应力对应的应变损失率,同时增加梁的韧性;加载位移为20 mm时,海水侵蚀后有纤维的梁最终拉伸损伤比无纤维的梁最终拉伸损伤减小4.9%,最终压缩损伤比无纤维的梁最终压缩损伤减小16.2%。     

薄膜型LNG船全船结构屈服和疲劳强度分析

以某薄膜型液化天然气（Liquefied Natural Gas,LNG）船的结构设计为例,开展全船屈服强度校核和基于精细网格的有限元疲劳强度分析。针对5种典型装载状态,基于美国船级社（American Bureau of Shipping,ABS）全船强度直接计算指南,采用ABS-DLA/SFA系列软件,用三维波浪载荷预报程序对波浪随机载荷进行长期预报。基于预报结果,针对每种装载状态计算15个设计波参数组,求解全船结构在各载荷组合工况下的应力分布,继而完成屈服强度校核。以甲板机械室与穹顶甲板相交处的关键节点区域的节点设计为例开展细网格局部强度分析,并通过各种改进设计解决应力集中问题。针对2种常用典型操作装载状态及营运于北大西洋海区疲劳寿命满足40a的要求,基于ABS全船疲劳强度直接计算指南计算2个典型细化位置热点应力传递函数,通过谱分析得到疲劳累积损伤和疲劳寿命,完成疲劳强度校核。采用的全船强度和疲劳分析方法和思路适用于其他超大型船舶的结构分析。