2507双相不锈钢在SO2污染模拟海水中的腐蚀行为

采用开路电位、电化学阻抗谱(EIS)、Mott-Schottky曲线和浸泡腐蚀实验研究了2507双相不锈钢在含不同浓度(0,0.001和0.01 mol·L-1)NaHSO3模拟海水中的腐蚀行为.研究表明:开路电位随NaHSO3浓度的增加而负移,腐蚀倾向增大;电荷转移电阻Rt随浓度的增加而减小,耐蚀性降低;2507不锈钢的腐蚀形态为局部腐蚀,点蚀程度随浓度升高有所加剧,腐蚀速率随浓度的增加而增大;Mott-Schottky曲线和成膜后电化学阻抗谱测试表明,NaHSO3的加入增加了2507不锈钢表面钝化膜的点缺陷浓度,降低了钝化膜的稳定性,电荷转移阻力减小,腐蚀更容易发生.这可能归因于NaHSO3的加入增加了模拟海水的酸度,并随NaHSO3浓度的增加促进了不锈钢表面钝化膜的破坏.     

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.     

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.     

316L不锈钢在醋酸溶液中的钝化膜电化学性质

通过电化学阻抗方法测量316L不锈钢在25～85 ℃的醋酸溶液中的EIS曲线和Mott-Schottky曲线,并测量各温度点下的循环伏安曲线,研究了钝化膜的电化学性质. 研究结果表明:在醋酸溶液中的阻抗谱表明316L不锈钢在25～85 ℃温度范围内均能形成稳定的钝化膜,随温度升高极化阻力下降而界面电容增大. 温度对于316L不锈钢钝化膜的半导体本征性质没有根本的影响:在-0.5～0.1 V电位区间内钝化膜呈p型半导体特征;在0.1～0.9 V电位区间内钝化膜呈n型半导体特征;在0.9～1.1 V电位区间内钝化膜呈p型半导体特征. 钝化膜的循环伏安曲线显示当温度低于55 ℃时,钝化膜结构比较稳定;当温度为55 ℃时,钝化膜稳定性趋向恶化;当温度超过55 ℃时,钝化膜稳定性下降.     

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.     

酸性溶液中碳钢上钝化膜的生成和溶解

碳钢上的钝化膜为不均匀膜,其稳定性比纯铁的钝化膜低,并随酸度的降低和钝化时间的增长而增加。在0.8V钝化一个半小时后,开路电位衰减曲线出现两个平台。采用方波迭加法模拟了电流振荡现象。     

不锈钢阳极钝化行为的电化学调制光谱研究

利用电化学调制光谱,并结合电化学稳态法和交流阻抗技术,研究了304不锈钢在含Cl~-离子介质中的阳极钝化行为。初步结果是:当不锈钢处于阳极钝化区,其表面钝化膜的化学组分、价态及介电性质等随电化学环境的不同,而发生复杂的变化;在不同的电位区,其表面组分富集不同;钝化膜中的物质价态随电位正移,从低价态向高价态过渡变化;介质中的Cl~-离子对钝化膜中组分具有选择性的活化溶解作用,这种作用可从离点腐蚀特征电位较远的低电位区开始,且随电位的正移而愈趋强烈。     

注Cr对质子交换膜燃料电池不锈钢双极板腐蚀行为的影响

应用金属蒸气真空弧(MEVVA)离子注入技术,在316L不锈钢表面注Cr改性,对改性层化学成分和微观结构进行表征分析,运用电化学测试技术考察其在模拟质子交换膜燃料电池(PEMFC)环境中的腐蚀行为。结果表明:不锈钢表面形成富Cr改性层,Cr离子浓度沿纵向呈梯度分布且无界面,改性层厚度随加速电压升高而增大;Cr离子浓度随离子注量的增加而增大;不锈钢表面粗糙度降低、致密度增大,有利于腐蚀电流的降低;不锈钢在阴阳两极模拟加速腐蚀环境下均更易钝化,腐蚀倾向大幅度降低,可有效提高耐腐蚀性。     

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。     

316L和316LN不锈钢在高温高盐溶液中钝化膜的性能研究

利用电化学及扫描电子显微镜（SEM）对316L与316LN两种不锈钢在高温高盐环境中的耐蚀性能进行了对比研究,利用Mott-Schottky曲线研究了两种材料的钝化膜半导体特征,借助X射线光电子能谱（XPS）研究了316LN不锈钢的钝化膜结构以及N元素在钝化膜中的分布状态。结果表明：在高温高盐环境中,两种材料形成的钝化膜都为n型半导体;316LN不锈钢形成的钝化膜耐点蚀性能更好,其钝化膜内缺陷浓度更低,N元素会在钝化膜中富集。最后利用点缺陷原理对316LN钝化膜的耐蚀机理进行了研究。     

Properties of passive film formed on 316L/2205 stainless steel by Mott-Schottky theory and constant current polarization method

Semiconductor properties of the passive films formed on 316L and 2205 stainless steel were studied by Electrochemical Impedance Spectroscopy(EIS) in the high-temperature acetic acid.The results showed that the corrosion resistance of 2205 was higher than that of 316L,and the passive films formed on 316L and 2205 stainless steel showed p-type and n-type semiconductor behavior,respectively.Destruction and self-repairing of passive films were studied by using the constant current polarization method.The result...     

用SEM研究氯离子对铁的钝化膜的作用

利用扫描电子显微镜（ＳＥＭ）研究酸性溶液中氯离子对铁钝化过程的作用，ＳＥＭ实验结果表明：氯离子破坏了在铁的阳极钝化区域内形成的钝化膜，并引起孔蚀；硝酸根离子能够抑制氯离子引起的孔蚀，并使铁恢复钝化状态。这些实验结果与电化学方法获得的结果相一致．     

退火条件对多晶硅薄膜光电性能的影响

采用氢等离子体加热的方法晶化a-Si:H薄膜制备多晶硅薄膜,用Raman散射谱和傅里叶变换红外吸收谱(FT-IR)等方法进行表征和分析.研究了退火的射频功率、衬底温度和退火时间对薄膜微结构和光电性能的影响.结果表明,薄膜的氢含量是影响薄膜光学带隙的主要因素,而薄膜的结晶度是影响薄膜暗电导率的主要因素.     

LiCl对脂肪族聚氨酯脲结构与性能的影响

通过FT-IR和DSC等研究了L iC l对脂肪族聚氨酯脲溶液粘度以及聚氨酯脲膜的结构和性能的影响。研究结果表明:L iC l的加入使聚氨酯脲溶液的初期粘度降低,后期粘度升高;含L iC l的聚氨酯脲的Tg和氨酯羰基的氢键化程度提高,但脲羰基的氢键化程度降低;L iC l的加入使聚氨酯脲的拉伸模量、硬度、撕裂强度和吸水率显著升高。     

热镀铝锌层镧掺杂硅烷钝化膜的腐蚀性能

采用掺杂硝酸镧的硅烷(BTESPT)钝化液处理热镀铝锌层:室温(25℃)浸渍,120℃固化30min,在铝锌层上形成镧盐掺杂硅烷钝化膜.研究了热镀铝锌基体钝化后的结构、表面形貌与腐蚀性能.傅立叶变换红外光谱(FTIR)表明,掺杂硝酸镧的硅烷溶液与铝锌基体表面发生了化学键合作用,形成SiOAl与SiOZn网络结构的钝化膜,钝化膜中主要的有机基团种类与无掺杂剂硅烷膜无显著差别.SEM/EDS研究结果表明:掺杂硝酸镧的硅烷膜均匀、致密、无明显微裂纹,硅烷膜中主要含有C,O,Si,S,Al,Zn,La等元素.耐蚀性研究表明,掺杂硝酸镧的硅烷钝化能明显降低腐蚀电位和腐蚀电流密度,增大极化电阻,使其耐蚀性...     

Molecular dynamics simulation of the deposition process of hydrogenated diamond-like carbon （DLC） films

The deposition process of hydrogenated diamond-like carbon （DLC） film greatly affects its frictional properties. In this study, CH3 radicals are selected as source species to deposit hydrogenated DLC films for molecular dynamics simulation. The growth and structural properties of hydrogenated DLC films are investigated and elucidated in detail. By comparison and statistical analysis, the authors find that the ratio of carbon to hydrogen in the films generally shows a monotonously increasing trend with the increase of impact energy. Carbon atoms are more reactive during deposition and more liable to bond with substrate atoms than hydrogen atoms. In addition, there exists a peak value of the number of hydrogen atoms deposited in hydrogenated DLC films. The trends of the variation are opposite on the two sides of this peak point, and it becomes stable when impact energy is greater than 80 eV. The average relative density also indicates a rising trend along with the increment of impact energy, while it does not reach the saturation value until impact energy comes to 50 eV. The hydrogen content in source species is a key factor to determine the hydrogen content in hydrogenated DLC films. When the hydrogen content in source species is high, the hydrogen content in hydrogenated DLC films is accordingly high.     

Properties of passive film formed on 316L / 2205 stainless steel by Mott-Schottky theory and constant current polarization method

Semiconductor properties of the passive films formed on 316L and 2205stainless steel were studied by Electrochemical Impedance Spectroscopy （EIS） in the high-temperature acetic acid. The results showed that the corrosion resistance of 2205 was higher than that of 316L, and the passive films formed on 316L and 2205 stainless steel showed p-type and n-type semiconductor behavior, respectively. Destruction and self-repairing of passive films were studied by using the constant current polarization method. The results showed that for 316L, the self-repairing process would occur when the destruction was lower than the critical extent or it would not do; for 2205, the self-repairing process only happened in a short time when the destruction was in the same extent as 316L.     

Hydrogen distribution in CVD diamond films prepared by DC arcjet operating at gas recycling mode

Hydrogen distribution and content in diamond films deposited by DC arcjet under gas recycling mode was evaluated by nuclear reaction analysis (NRA). The films were characterized using scanning electron microscopy, X-ray diffraction and Raman spectrometry. The NRA results show that the hydrogen content in diamond films was approximately 0.6% (substrate temperature 770℃), and strongly depended on the substrate temperature. It was that the hydrogen content increased with the increase of the substrate temperature. The possibility of hydrogen trapping in the films was also discussed.     

Fabrication of tungsten films by metallorganic chemical vapor deposition

Tungsten films growing on copper substrates were fabricated by metallorganic chemical vapor deposition (MOCVD). The chemical purity, crystallographic phase, cross-sectional texture, and resistivity of the deposited films both before and after annealing treatment were investigated by X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and four-point probe method. It is found that the films deposited at 460℃ are metastable β-W with (211) orientation and can change into α-W when annealed in high-purity hydrogen atmosphere at high temperature. There are small amounts of C and O in the films, and the W content of the films increases with increasing deposition temperature and also goes up after annealing in high-purity hydrogen atmosphere. The films have columnar microstructures and the texture evolution during their growth on copper substrates can be divided into three stages. The resistivity of the as-deposited films is in the range of 87-104 μΩ·cm, and low resistivity is obtained after annealing in high-purity hydrogen atmosphere.