304不锈钢双极板性能研究

以304不锈钢做为研究对象,测定了其在模拟PEMFC环境下的极化曲线,极化时间分别为4h和10h的交流阻抗谱,用伏安法测量了304不锈钢表面氧化膜／钝化膜与碳纸之间的接触电阻。实验结果表明,304不锈钢能够钝化且钝化电流密度低于16μA·cm^-2;随着极化时间增加,不锈钢表面生成的钝化膜的界面极化电阻增加,表面钝化膜有增厚的趋势;经过恒电位极化后,304不锈钢的钝化膜与碳纸的接触电阻显著增加,模拟阴极环境的接触电阻大干模拟阳极环境的接触电阻。     

镀铬不锈钢双极板在PEMFC环境中的性能

为克服不锈钢表面存在的钝化膜非均匀性的缺陷,采用镀铬方法对304不锈钢进行表面改性,研究表面镀铬的304不锈钢在模拟质子交换膜燃料电池(PEMFC)环境中的电化学性能和电性能.结果表明:在不锈钢表面生成了厚7～8μm的均匀完整的镀铬层;镀铬的304不锈钢在模拟PEM-FC阴极和阳极环境中均具有比基体更低的钝化电流密度,更易于钝化;在空气中形成的氧化膜较基体具有更低的界面接触电阻,恒电位极化后表面生成的钝化膜可引起表面接触电阻的增加.     

电沉积铅改性304不锈钢双极板在模拟PEMFC环境中的性能

为提高304不锈钢双极板的耐腐蚀性能,分别采用直流和脉冲电刷镀铅对其表面改性.采用电化学方法测定了改性前后304不锈钢在模拟PEMFC环境下的极化曲线,在扫描电镜 (SEM) 下观察了模拟腐蚀后的表面形貌,并用伏安法测量了改性前后304不锈钢的接触电阻.在模拟PEMFC环境中,改性后304不锈钢自腐蚀电流密度由10.83μA/cm2下降至6.18μA/cm2.经200h模拟腐蚀后,304不锈钢表面发生点蚀,而改性不锈钢板表面完整,未观察到明显腐蚀.改性后的接触电阻也有所降低.结果表明,电沉积铅能有效提高304不锈钢在模拟PEMFC环境中的耐腐蚀性能,可望满足PEMFC环境下长期耐腐蚀的要求.     

304不锈钢在模拟压水堆一回路水中高温电化学腐蚀行为

通过模拟压水堆一回路水环境,研究了氯离子浓度和溶解氧对304不锈钢高温电化学腐蚀行为的影响.动电位极化曲线结果表明,氯离子浓度主要影响高电位下的二次钝化效应,低电位下影响效果不明显,结合X射线光电子能谱对氧化膜元素成分的分析发现二次钝化效应与氧化膜中Fe/Cr元素含量比密切相关.电化学阻抗谱和扫描电镜结果表明,随着氯离子浓度增加,氧化膜阻抗逐渐降低,表面外层氧化物颗粒和间隙逐渐增大,耐腐蚀性能降低.随着溶解氧含量的升高,304自腐蚀电位逐渐升高,钝化电流密度降低,钝化区间缩小,表面氧化膜阻抗逐渐增加.     

静水压力对304不锈钢腐蚀行为的影响

利用自制的腐蚀实验高压釜模拟深海低温高压化学环境,研究静水压力对304不锈钢腐蚀行为影响机制.利用电化学工作站对腐蚀过程进行原位检测和加速实验,得到交流阻抗谱和动电位极化曲线,通过等效电路拟合和Tafel外推法对数据进行处理.分析了腐蚀发生的热力学倾向和动力学过程,讨论了钝化膜状态对腐蚀的影响.常压环境下,自腐蚀电位高,容抗弧半径较小.氧气等气体分子容易在304不锈钢表面吸附,增大腐蚀发生的热力学倾向.随着静水压力的增加,自腐蚀电位变化不大,压力变化不会导致钝化膜性质的改变.但腐蚀电流密度从3.838×10-8 A/cm2增加到1.197×10-7 A/cm2,容抗弧半径减小,金属/钝化膜/溶液之间电位差降低,钝化膜溶解速率大于生长速率,导致钝化膜厚度减小,使304不锈钢腐蚀加剧.     

304和316L不锈钢的高温电化学腐蚀行为

通过模拟压水堆一回路水环境,研究了溶液温度和溶氧量(DO)对304和316L不锈钢高温电化学腐蚀行为的影响.结果表明:随着溶液温度升高,在304和316L不锈钢表面所形成的氧化膜的保护性能降低;随着DO升高,304和316L不锈钢的自腐蚀电位升高,自腐蚀电流密度降低,钝化区缩小;304和316L不锈钢表面形成了双层氧化膜,外层氧化膜颗粒尺寸和颗粒间隙随着温度的升高而增大,随着DO增加而减小;在所用实验条件下,316L不锈钢表现出比304更优异的抗腐蚀性能.     

温度对SUS304与SUS430不锈钢耐腐蚀性及其钝化膜半导体性能的影响

使用SUS304与SUS430不锈钢作为研究材料,应用动电位极化曲线、交流阻抗谱(EIS)和电容电位法(Mott-Schottky)等电化学研究方法,对比研究了SUS304与SUS430不锈钢在1mol/L的NaHCO3溶液中、20~80℃温度内的腐蚀性能及其钝化膜半导体性能。结果表明,随着温度的升高,SUS304与SUS430不锈钢自腐蚀电流增加,溶液电阻与极化电阻减小,弥散效应增强;由M-S曲线知,在-0.5~0.5V电位区间,20~80℃温度内,SUS304与SUS430不锈钢钝化膜均表现为n型半导体性质,M-S曲线拟合直线斜率随温度的升高而降低,平带电位负移;可见在温度作用下,钝化膜半导体费米能级正移,使能级差减小而造成以氧空位为主要点缺陷的浓度增大,导致SUS304与SUS430不锈钢腐蚀加剧。其中SUS304奥氏体不锈钢比SUS430铁素体不锈钢具有较好的耐蚀性。本研究对探索腐蚀机理与选择合理的防腐新材料具有一定的借鉴作用。     

奥氏体不锈钢双极板的低温超饱和气体渗碳表面改性

通过低温超饱和气体渗碳(LTCSGC)处理,在316L不锈钢双极板表面形成了一层厚度约30μm的渗碳层,研究了从基体沿渗碳层深度方向的碳的质量分数、残余应力、硬度分布和相结构,测量了渗碳后316L不锈钢双极板的接触电阻,分析了渗碳后316L不锈钢双极板在模拟质子交换膜燃料电池(PEMFC)环境中的耐腐蚀性能.结果表明:渗碳层是由膨胀奥氏体相组成的梯度材料,从渗碳层表面到基体的碳的质量分数、残余应力和硬度逐渐降低;经过LTCSGC处理后,316L不锈钢双极板的接触电阻降低了34%;在模拟PEMFC的阳极环境中,其自腐蚀电位升到-79 mV,高于工作电位-0.1 V,获得了阴极保护;在模拟PEMFC的阴极环境中,其自腐蚀电位提高了260 mV,抗腐蚀性能显著提高,恒电位极化腐蚀电流密度降低了75%.     

增强不锈钢表面耐蚀性的研究进展

不锈钢是使用范围广泛且环保的一种耐蚀材料,但不锈钢在空气中自钝化形成的氧化膜的耐蚀性不佳,因此后续钝化处理是提高不锈钢表面耐蚀性的重要方法.本文综述了提高不锈钢表面耐蚀方法的研究进展.介绍不锈钢的钝化机理、硝酸钝化方法与柠檬酸钝化方法的最佳工艺.总结动电位极化曲线、电化学阻抗谱、Mott-Schottky曲线、循环伏安法和磨损-电化学腐蚀共五种不锈钢钝化膜耐蚀性测试方法.梳理塑性变形对不锈钢耐蚀性的影响,强调适度的塑性变形能够提高不锈钢耐蚀性.展望不锈钢钝化处理及塑性变形增强不锈钢钝化效应的研究趋势.     

304 L不锈钢焊缝在混凝土模拟孔隙液中的点蚀行为

采用动电位极化曲线、电化学阻抗谱、Mott-Schottky曲线等电化学方法研究了以308 L为焊丝的304 L不锈钢焊接接头在不同氯离子含量的混凝土模拟孔隙液中腐蚀行为和电化学规律。随Cl-增加,304 L不锈钢焊接接头的三个区域(母材、焊缝和热影响区)在混凝土模拟孔隙液中的自腐蚀电位、点蚀电位及电荷转移电阻降低,钝化膜中载流子密度和焊接接头的点蚀坑数量增加。在同浓度的腐蚀溶液中,308 L的焊缝区域耐蚀性最佳,热影响区次之,304 L基体表现出低的电荷转移电阻和高的掺杂浓度使得母材的耐蚀性最差。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with