铝阳极氧化厚膜的制备工艺研究

对铝在硫酸溶液中采用阳极氧化的方法制取厚氧化膜的工艺进行了研究.相同工艺条件下,在硫酸溶液中加入添加剂,可使氧化膜的成长速度大大提高,并扩大允许的温度范围.采用逆电剥离法可剥离厚铝氧化膜.     

电化学法研究铝阳极氧化膜的抗腐蚀性

工业纯铝L2在硫酸溶液中进行阳极氧化制得阳极氧化膜,测试了此阳极氧化膜在NaCl溶液中的电化学性能。通过动态极化法和交流阻抗法对阳极氧化膜进行分析,发现阳极氧化膜的制备条件(电解液浓度、时间、电压等)不同时,膜的抗腐蚀性能也不同。电化学阻抗法测定表明,随浸泡时间的增加,膜阻抗值明显增大,可能是多孔膜在介质溶液中存在一个自然水合封闭的过程。     

6063铝型材在不同pH值硫酸溶液中的阻抗行为

运用化学交流阻抗技术测试了６０６３铝型材在不同ｐＨ值的硫酸水溶液保的阻抗谱。结果表明，该溶液体系为吸附型体系；当ｐＨ≥２时，反应电阻Ｒｒ、双电层容抗Ｃｄ的变化近似一平台，表面有钝化膜生成；而当ｐＨ〈２时，Ｒｒ值较小，铝以较快速度活性溶解。研究认为，控制阳极氧化预处理工艺中的清洗水的ｐＨ值能抑制腐蚀缺陷，特别是雪花状腐蚀缺陷的出现。     

自熔合金粉末喷熔层耐蚀性能的探讨

通过对国产四种自熔合金粉末喷熔层在盐酸，硫酸，硝酸和氯化钠溶液中的腐蚀试验，探讨了腐蚀介质种类，酸性溶液浓度和ｐＨ值，喷熔层的化学成分和显微组织对腐蚀速率的影响。     

铅阳极膜的半导体性能

利用微分电容法结合Mott-Schottky理论研究铅电极1.28V(vsSCE)下硫酸溶液中所形成阳极腐蚀膜的半导体性质,同时对测试频率、成膜时间及成膜溶液pH值等影响膜半导体性能的因素也做了分析。结果表明:铅阳极膜具有n型半导体特性,施主密度ND随测试频率的增加而减小,随极化时间的延长而增加,随溶液pH值的增加而减小。溶液pH值的改变可以显著影响膜的平带电位EFB,两者间呈线性关系,拟和斜率为60.43。     

碳钢表面自组装膜缓蚀性能的研究

采用分子自组装技术在碳钢表面制备了苯基三乙氧基硅烷自组装膜,利用单因素和正交实验找到最佳组装工艺条件。通过Tafel曲线研究了该工艺条件下自组装膜对碳钢在10%硫酸介质中的缓蚀性能。结果表明:水解55h后,温度为40℃、pH值为4.5、V_(苯基三乙氧基硅烷)∶V_(超纯水)∶V_(无水乙醇)=2∶5∶45时,溶液的电导率最大。该条件下自组装膜对碳钢有良好的缓蚀效率,随着组装时间的增加,对碳钢的缓蚀效率会更好。     

AISI304不锈钢钝化膜在电解质溶液中腐蚀时的半导体性质

应用电位-电容测试和Mott-Schottky分析技术研究了AISI304不锈钢钝化膜在电解质溶液中的半导体性质.结果表明,不锈钢钝化膜在氢氧化钠溶液中,随着浸泡时间延长,半导体类型转变电位发生负移;在硫酸、硫酸钠两种溶液中转变电位无明显变化.随着腐蚀时间的延长,溶液中不锈钢钝化膜的载流子密度逐渐增加,其载流子密度在几种溶液中从小到大的顺序依次为硫酸钠,氢氧化钠,硫酸.不锈钢在三种溶液中的Mott-Schottky曲线均出现频率分化,其原因可能为钝化膜中载流子的产生-复合存在时间效应;在氢氧化钠溶液中,钝化膜腐蚀的主要原因为富铬层导电能力增强;在硫酸、硫酸钠两种溶液中,钝化膜腐蚀的主要原因为富铁层导电能力的增强.     

铁基金属表面苯胺及其衍生物电化学修饰膜的缓蚀作用

研究结果表明,苯胺及其衍生物的电化学修饰膜对铁基金属有很好的保护作用,在氯化钠溶液以及弱酸性和强碱性溶液中有良好的阻蚀性能。18-8不锈钢经修饰后在3％NaCl溶液中的耐孔蚀性能大为提高,在硫酸溶液中的钝化特性明显改善。根据实验结果,探讨了修饰膜的缓蚀机理以及修饰物质的结构、取代基的位置对修饰膜耐蚀性的影响。     

金属表面多孔膜的保护作用与介质组分的关系

研究了铝阳极氧化多孔膜层界面电性能与溶液介质组分的关系。多孔膜在介质中存在一等电点ＰｈＩＥＰ,当溶液ＰＨ〈ＰＨＩＥＰ时,膜荷正电具有阴离子选择性：ＰＨ〉ＰＨＩＥＰ时,膜荷负电具有阳离子选择性。介质中的一些组分可通过与膜孔表面的相互作用改变膜的ＰＨＩＥＰ,从而发迹膜的荷遇性能手     

铝阳极氧化膜的硫酸钇脉冲封闭

研究了硫酸钇脉冲封闭对工业纯铝阳极氧化膜受热开裂行为及电化学行为的影响.利用扫描电子显微镜(SEM)观察了沸水封闭和钇盐脉冲封闭后阳极氧化膜的表面和截面形貌.利用电化学交流阻抗谱(EIS)和极化曲线研究了两种封闭方法的电化学腐蚀行为.结果表明,通过硫酸钇脉冲封闭,可以将钇元素引入到氧化膜中.与沸水封闭氧化膜加热后表面出现了宽度达1 μm的粗大的裂纹相比,硫酸钇封闭的氧化膜表层更加致密,其多孔层孔壁的加粗、孔隙减小,氧化膜显微硬度明显提高,使得氧化膜在加热后仅出现一些细小的微裂纹.从交流阻抗结果可以看出,硫酸钇封闭氧化膜的Rp值是沸水封闭氧化膜的1.43倍,极化曲线结果表明,经过钇盐封闭后,氧化膜的自腐蚀电位比沸水封闭的试样正移约280 mV,自腐蚀电流密度降低为沸水封闭试样的0.41.钇盐封闭的氧化膜在NaCl溶液中的耐蚀性能也有显著提高.     

黄铜药筒表面防锈ATA自组装膜实验研究

黄铜药筒长期储存过程中表面易发生锈蚀,严重影响了弹药的正常使用.ATA具有很强的螫和性,是一种有效的环境友好型金属缓蚀剂,在黄铜药筒表面包覆ATA自组装膜对缓解药筒锈蚀具有一定的可行性.笔者通过试验在黄铜药筒表面包覆ATA自组装膜,采用EDS能谱分析,电位-时间曲线对对药筒表面覆膜情况进行了分析,通过失重实验初步研究了...     

膜式水冷壁管屏平角、仰角MAG焊接工艺研究

详细讨论了锅炉膜式水冷壁管屏采用平、仰角同时进行MAG焊接的工艺及规范，并进行了工艺试验。试验结果表明采用该规范焊制的膜式水冷壁产品，成形美观，导热性能符合相关标准要求，对实际生产有一定指导意义。     

几种新型的磁记录介质

目前磁记录技术的发展遇到了瓶颈,记录密度达到了极限.继续提高记录密度需要采用具有超高磁晶各向异性的记录介质材料,但这些材料的矫顽力巨大,使得数据的写入困难.为了摆脱这种困境,科研工作者提出了几种新型的磁记录介质的概念如倾斜介质、梯度介质、渗透垂直介质,并开展了相应的研究.本文综述了这几种新型的磁记录介质的研究进展.     

水平振动抛磨颗粒介质流场特性分析

目的 探索不同振动参数下水平振动抛磨颗粒介质的流动模式和流场特性.方法 基于离散元法(DEM),对水平振动抛磨工艺下的颗粒介质运动特性进行模拟,分析颗粒介质的流场特征和不同参数下颗粒介质的流态变化,研究颗粒介质床层高度比、空区变化和对流面积比对整个颗粒系统对流强度的影响,以及颗粒介质的平均速度对流场的影响,并通过高速摄影速度测试实验验证模拟的有效性.结果 在外部振动作用下,颗粒介质流场可分为对流区、混流区和稳流区3个区域.随着频率的增加,颗粒介质的平均速度在18 Hz达到最大,然后减小.随着振幅的增加,颗粒介质的平均速度增大.颗粒介质的床层高度比、空区和对流面积比的变化与平均速度随振动参数的变化趋势一致.结论 随着振幅增大或是频率达到18 Hz左右时,平均速度变大,颗粒介质床层逐渐由上层到下层从只有稳流类固态转变为有对流与混流的类液态.颗粒介质的平均速度与对流强度的变化趋势一致,因此可通过前者预测后者的变化,而且增加振幅比增加频率能够更有效地提升对流的流化程度.     

Corrosion of mild steel in porous media

The corrosion process in large-particle porous media is investigated with particular reference to corrosion in bulk carriers (ships). Examples of large-particle porous media include raw materials such as coal and iron ore which typically have particle sizes ranging up to approximately 50 mm diameter. It is proposed that the corrosion process is dominated by finer particles which co-exist with the larger particles. A mathematical model of the corrosion process is developed and used to estimate corrosion rates. These are shown to compare well with experimental results. The analysis indicates that to minimise corrosion it is desirable to maintain the moisture content of porous media in contact with mild steel either to less than 50%, or to more than 80%, of the maximum water holding capacity of the media.     

EFFECT OF SULFATE–REDUCING BACTERIA ON THE PITTING CORROSION BEHAVIOR OF 18–8 STAINLESS STEEL

利用原子力显微镜(AFM)和电化学方法研究了海水中硫酸盐还原菌(SRB)对18--8不锈钢(18--8SS)点蚀过程的影响. AFM探测显示, 微观蚀孔的生长速率在含SRB介质中明显高于在灭菌介质中. 阳极循环极化结果表明, SRB的代谢产物显著降低了18--8SS的点蚀电位和再钝化电位; 而且在含SRB介质中, 18--8SS在短时间内就能被活化, 表明SRB的代谢活动极大地促进了钝化层的破坏过程. 阴极极化曲线表明, 含SRB介质中单质硫或多态硫的还原是促使点蚀生长的主要因素, 其阴极还原电流密度可以达到很高的数值(>10 μA/cm²).     

Performance evaluation and rheological characterization of newly developed butyl rubber based media for abrasive flow machining process

The precision manufacturing technology always demands a good surface finish at low cost. This scenario drives both industries and research community to develop novel finishing processes. Presently, there are many techniques and one among them is abrasive flow machining (AFM) process. The media developed by optimum process variables mainly governs the performance of AFM. In the present experimental endeavor, an attempt is made in the direction of developing new media based on viscoelastic carrier and its characterization for fine finishing through AFM process. The newly developed media was again characterized through rheological properties. It is found that temperature, shear rate, creeping time and frequency have impact on rheological properties and the percentage ingredients of media govern trends of their relations.     

A Study on Tribology in Minimal Quantity Lubrication Cutting

Despite the fact that minimal quantity lubrication (MQL) machining produces almost similar cutting performance to conventional flood supply machining while using much less metal working fluid (MWF), it has not been fully utilized in industry due to lack of understanding of the fundamental process physics. To take full advantage of MQL machining and expand its applicability, an understanding of its tribological behavior is critical. Hence, in this study, the adsorption characteristics of MQL media during orthogonal cutting was investigated using two experimental setups; one in a high vacuum chamber with a mass spectrometer to observe mass changes of MQL media during cutting, and another setup in an atmospheric chamber where the supply of MQL media can be controlled. The former is mainly for analysis of the tribological behavior of MQL media, and the latter for cutting performance monitoring. It was found that the adsorption amount of MQL media was closely related to lubrication behavior. Oxygen in MQL supply plays a significant role in lubrication. Ultrasonic vibration cutting tests with MQL were conducted for further understanding of lubrication mechanism.     

选矿厂细磨磨矿介质的选择及研究

介绍、分析研究了选矿厂细磨中的磨矿介质选择的方法。从磨矿介质的尺寸、形状、材质 3个方面 ,进行了理论研究和实验验证 ,提出了一个可行的方案。     

Conveying Cutting-Edge Discoveries to Nonscientists: Effective Communication with Media

The benefits of using information and news media for disseminating cutting-edge scientific discoveries to the public are well known. Taxpayers and lawmakers need to be informed about the implications of public investments, young students’ interest can be molded toward science- and technology-based careers, and public awareness of important issues can be raised by effectively using media. However, communication with news media is different from the means commonly used by scientists—journal publications and conference presentations. This article is intended to provide information on three basic aspects of media interactions—why, what, and how to communicate. The increasing importance of this mode of dissemination in this information age cannot be ignored; rather, it can be effectively utilized for educating a wider population base.