铝合金表面杂化膜层的制备和耐蚀性研究

以γ-缩水甘油醚丙基三甲氧基硅烷(GPS)和双酚A(BPA)为主要原料,采用溶胶-凝胶工艺在铝合金表面制备了纳米GPS/BPA杂化膜层,通过动电位极化(PDS)法确定了制备较好防护性杂化膜层的GPS、BPA摩尔比,用反射吸收红外光谱(RA-IR)对AA2024-T3铝合金表面杂化溶胶交联前后的变化进行了表征,并用扫描电子显微镜(SEM)分析了交联后膜层中无机相的分布.采用盐雾试验和电化学阻抗谱(EIS)测试了这种杂化膜层的防腐蚀性能.结果表明,无机相呈颗粒状均匀分布在膜层中,颗粒平均大小45～80 nm,GPs和BPA摩尔比为1∶1时杂化膜层的防腐蚀保护性能最优.固化后的杂化膜层中仍有环氧基团剩余,膜层和基体界面处形成了铝硅氧烷(Al-O-Si)共价键网络.盐雾试验后未有明显腐蚀现象,但在0.5%NaCl溶液中浸蚀24 h后的EIS分析表明膜层和基体界面处发生了腐蚀.     

铝合金表面硅烷化膜层的表征及电化学分析

为了充分地了解双-[3-(三乙氧基)硅丙基]硫化物(BTESPT)水溶胶和膜层的形成过程及结构变化,采用傅立叶反射吸收红外光谱(FTIR-RA)和电化学阻抗谱(EIS)分析以及扫描电子显微镜(SEM)观察分析,对沉积在YL12铝合金表面的BTESPT水溶胶膜层进行了表征.结果表明,水解时间和固化工艺对膜层的组分和结构有显著影响,高温固化形成膜层的电化学阻抗比室温陈化形成膜层的阻抗更高,并且室温预陈化后的膜层在非腐蚀性水溶液中需进一步陈化才能提高膜层的致密性和均匀性.     

电流密度对铝合金微弧氧化膜的生长及结合力的影响

为了进一步探讨微弧氧化主要参数电流密度对铝合金微弧氧化膜的影响机理,先用微弧氧化技术在LY12硬铝合金上获得陶瓷层,然后考察电流密度对陶瓷膜厚度及其与基体结合强度的影响,再利用扫描电镜(SEM)、X射线衍射(XRD)、光电子能谱(XPS)分析了氧化膜的形貌和组织结构,通过划痕试验和冲击试验研究了氧化膜与基体的结合力.结果表明,随着电流密度的增大,陶瓷氧化膜及其致密层的增长速度均加快,但有一个极限值,氧化膜的临界载荷降低,致密层所占比例也逐渐降低.XPS谱图证明,微弧氧化膜表面疏松层主要由γ-Al2O3,α-Al2O3和Al-Si-O相组成,致密层由α-Al2O3和γ-Al2O3组成.铝合金表面生成氧化膜后,随着膜厚度的增加,冲击韧性逐渐减低,基体断裂后,氧化膜没有发生剥落,表面出现大量微裂纹.     

在稀硫酸中添加硫脲对块体纳米晶纯铁腐蚀行为的影响

研究了在稀硫酸溶液中添加硫脲(TU)对块体纳米晶工业纯铁(BNII)室温电化学腐蚀行为的影响,并与普通工业纯铁(CPII)的室温电化学腐蚀行为进行了比较.结果表明:将CPII在添加TU的稀硫酸溶液中浸泡5 min,其电化学阻抗(EIS)谱图中出现感抗弧.随着浸泡时间的延长,CPII的EIS谱图表现为一非圆心下偏的半圆;而在相同的条件下,BNII的EIS谱图表现为两个时间常数的容抗弧,表明硫脲对其腐蚀行为有促进作用.动电位极化(PDP)测试结果表明,两种材料的样品均出现阳极脱附现象.     

LY12铝合金表面有机-无机杂化膜的防腐性能研究

以乙烯基三甲氧基硅烷(VMS)、γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPMS)和γ-环氧丙基醚基三甲氧基硅烷(GPMS)三种硅烷偶联剂为前驱体,制备了正硅酸乙酯(TEOS)改性的有机-无机杂化膜.采用动电位极化曲线测试了膜层的防腐性能,考察了TEOS含量对其的影响.以腐蚀电流为指标,比较了三种体系杂化膜的防腐能力.利用盐雾试验和电子扫描照片研究了杂化膜耐长久腐蚀行为.结果表明,杂化膜的存在有效地抑制了腐蚀反应的发生,VMS和MPMS膜层可使腐蚀电流减小300多倍.当TEOS含量为15%～20%(质量分数,下同)时,膜层的腐蚀电流最小.比较而言,VMS-TEOS膜层的耐蚀能力最强,GPMS-TEOS膜层最差.VMS膜层和VMS 20%TEOS膜层耐盐雾腐蚀的能力最强,总体来说,杂化膜耐长久腐蚀的能力较差.     

不锈钢表面功能性硅氧烷膜的制备与性能研究

采用双功能性1,2-二(甲氧基二乙氧基硅基)乙烷为原料,在奥氏体304不锈钢表面制备了有机-无机杂化硅氧烷膜(BMBSE),并通过FTRA-IR、SEM、EIS、动电位极化曲线及接触角测量仪对薄膜的性能进行测试和表征.结果表明,致密完整无缺陷的双功能性BMBSE硅氧烷通过形成Si-O-Fe化学键与不锈钢基体结合;硅烷膜与水的接触角为94.2°,具有一定的疏水性;在55%的溴化锂溶液中的动电位极化曲线和EIS测试表明,双功能性硅氧烷BMBSE膜极大的改善了不锈钢的耐腐蚀能力.同时,给出了不锈钢表面双功能性硅氧烷BMBSE膜的阻抗模型以及相关拟合参数.     

用正硅酸乙酯改性的倍半硅氧烷膜压痕特性的研究

用压痕测实验研究了正硅酸乙酯(TEOS)改性剂的含量,对可涂于包装材料的倍半硅氧烷(SSO)膜的硬度和弹性模量的影响.SSO是由3-(2.3-环氧丙氧)丙基三甲氧基硅烷(GPMS)水解缩合反应制备的.膜的硬度和弹性膜量是由纳米压痕(IIT)设备的连续硬度测试(CSM)技术测定的.对膜体系改性后各种指标进行了分析.结果表明:摩擦学行为可以通过在涂层系统中添加不同含量的TEOS来影响,在含有20%TEOS的膜中,有最小的摩擦系数和较好的抗压痕性.     

6063铝合金表面钛/锆/钼转化膜的制备及自愈性

采用化学转化处理法在6063铝合金表面制备获得淡黄色的钛/锆/钼转化膜,通过浸泡法并借助电化学工作站考察了钛/锆/钼转化膜的耐蚀性,采用划痕法结合扫描电子显微镜(SEM)研究了钛/锆/钼转化膜的自愈性。转化液的组成为:2 g/L H_2TiF_6,2 g/L H_2ZrF_6,2 g/L有机酸着色剂,3 g/L Na_2MoO_4。结果表明,在pH=3.0、温度为35℃、时间为5 min的工艺条件下能够在6063铝合金表面获得淡黄色、致密且耐蚀性良好的膜层,膜层微观表面均匀分布着白色颗粒和裂纹。人工划痕的钛/锆/钼转化膜在3.5%NaCl盐雾氛围中随着浸泡时间的延长划痕逐渐愈合,形成新的膜层,这表明制得的膜层具有自愈性。当在中性盐雾中的腐蚀时间超过5 d后,划痕处附近膜层中的氧化剂不断被消耗,迁移至划痕处发生络合的物质逐渐减少,膜层自愈性能退化,膜层被腐蚀。     

铝合金表面自组装膜层的表征及耐蚀性研究

利用非水性三氯硅烷溶液作组装液,采用浸涂法在铝合金表面沉积自组装膜层(SAMs),用红外光谱(FTIR)和循环伏安法(CV)对膜层进行表征并用热盐浴浸湿法、动电位扫描和电化学阻抗谱(EIS)法对膜层的耐蚀性进行了研究.结果表明,在铝合金表面已形成疏水性组装膜层,该膜层表面仍有一定量的针孔存在,虽然对铝合金表面具有一定的阻隔保护作用,但在腐蚀性介质中仍存在点蚀现象.     

LY12铝合金微弧氧化陶瓷层的结构和性能

分析了LY12铝合金微弧氧化陶瓷膜的形貌、组成和结构,研究了氧化膜的硬度、与基体的结合强度以及在油润滑和干摩擦这两种条件下的摩擦学行为.结果表明,铝合金微弧氧化膜可分为疏松层和致密层,疏松层由α-Al2O3、γ-Al2O3以及Al-Si-O相组成,致密层由α-Al2O3和γ-Al2O3组成,致密层中α-Al2O3的含量远远高于疏松层.从表层到基体,微弧氧化膜的断面显微硬度先增大后减 小.微弧氧化膜与铝合金基体结合紧密.随着膜厚度的增加,氧化膜的临界载荷线性增加.氧化膜具有优良的抗磨性能,油润滑条件下的摩擦系数仅为干摩擦下的1/10.     

C60/PVK/CdS纳米粒子功能复合 LB 膜研究

目的 尝试用Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ（ＬＢ）技术组装Ｃ６０技术组装Ｃ６０功能复合体系的新方法。方法 采用（ＬＢ）技术制备Ｃ６０／ＰＶＫ／ＣｄＳ花生酸混合ＬＢ膜并利用界面化学反应技术将混合膜与硫化氢气体反应制得Ｃ６０／ＰＶＫ／ＣｄＳ纳米粒子功能复合ＬＢ膜并进行紫外光谱表征。结果 含不同比例Ｃ６０的Ｃ６０ＰＶＫ／ＡＡ体系可以在辐亚相上形成稳定的单层膜并转移到固体基片上得到了ＬＢ多层膜,ＬＢ混     

磁控溅射SiC/W纳米多层膜的微结构研究

用磁控溅射法在Si基底上制备了不同调制波长的SiC／W纳米多层膜。利用小角度X射线衍射技术（LXD），详细研究了其中典型的多层膜的调制周期性，各子层的厚度及界面平整度等界面微观结构。结果表明：磁控溅射法制备的纳米多层膜具有较好的周期结构及陡峭的界面梯度，由衍射峰位置计算出的界面不均匀度与子层厚度之比一般在5％以内。另外，对于小角度X射线衍射谱线中的所谓峰分裂现象进行了分析和计算。     

EIS Study on Pitting Corrosion of AA5083-H321 Aluminum-Magnesium Alloy in Stagnant 3.5% NaCl Solution

In this research, EIS （electrochemical impedance spectroscopy） technique was utilized to study the pitting corrosion behaviour of AA5083-H321 aluminum-magnesium alloy in 3.5% NaCl solution. Impedance spectra were obtained during 240 h of exposure of the sample to the test solution. The surface and cross-section of the samples were studied by scanning electron microscopy （SEM） and EDAX （energy dispersive analysis of X-ray） analysis. The results indicated that as the resistance of the passive layer on intermetallic particles is very small, this parameter on the sample surface layers is controlled by that of pure passive layer. However, the capacitors in the proposed equivalent circuit are replaced with the constant phase elements （CPE）, due to non-uniformity and occurrence of pitting corrosion on the surface. The outward diffusion of Al^＋3 ions through the passive layer and the thickening of this layer cause the impedance decrease in the first 24 h and increase afterwards. The detachment of intermetallic particles from some of pits and the accumulation of the corrosion products inside some others are factors that prevents the continuation of cathodic reactions on the top of the intermetallic particles.     

疲劳裂纹扩展试验载荷谱加重方法研究

为探索缩短疲劳裂纹扩展试验周期的载荷谱处理方法,对多种裂纹扩展模型进行了综述,概括出一种通用的裂纹扩展预测模型表达式。提出了一种将峰谷值同时等比例放大的载荷谱加重方法,并推导出加重前后裂纹扩展寿命的转换关系。用一种随机谱和两种块谱的基准谱及对应四种比例加重谱进行了LY12CZ中心裂纹板裂纹扩展试验,用常幅载荷谱及其1.1倍加重谱进行了典型机身壁板结构裂纹扩展试验。试验结果表明载荷谱等比例加重方法可以有效缩短疲劳裂纹扩展试验周期而不改变结构破坏模式,而分析结果表明由该方法预测的裂纹扩展寿命与试验结果的误差在15%以内,满足工程精度要求。     

Structural, dielectric and optical properties of Ba(Ti, Zr)O3 thin films prepared by chemical solution deposition

Ba(Ti_0.95Zr_0.05)O₃ (BTZ) thin films grown on Pt/Ti/SiO₂/Si(100) substrates were prepared by chemical solution deposition. The structure and surface morphology of BTZ thin films has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). At 100 kHz, the dielectric constant and dissipation factor of the BTZ film are 121 and 0.016, respectively. The ellipsometric spectrum of the BTZ thin film annealed at 730 °C was measured in the range of wavelength from 355 to 1700 nm. Assuming a five-layer model (air/surface roughness layer/BTZ/interface layer/Pt) for the BTZ thin films on platinized silicon substrates, the optical constant spectra (refractive index n and the extinction coefficient k) of the BTZ thin films were obtained.     

Electrochemical impedance spectroscopy characterization of passive film formed on implant Ti–6Al–7Nb alloy in Hank's solution

The influence of potential on electrochemical behavior of Ti-6Al-7Nb alloy under simulated physiological conditions was investigated by electrochemical impedance spectroscopy (EIS). The experimental results were compared with those obtained by potentiodynamic polarization curves. All measurements were carried out in Hank's aerated solution at 25 degrees C, at pH 7.8 and at different potentials (corrosion potential, 0 mV(SCE), 1000 mV(SCE), and 2000 mV(SCE)). The EIS spectra exhibited a two-step or a two-time constant system, suggesting the formation of a two-layer oxide film on the metal surface. The high corrosion resistance, displayed by this alloy in electrochemical polarization tests, is due to the dense inner layer, while its osseointegration ability can be ascribed to the presence of the outer porous layer.     

CF表面低聚倍半硅氧烷涂层对复合材料界面性能影响

采用不同倍半硅氧烷(SSO) ( YGO-SSO 和Methacryl isobutyl-POSS) 涂层对碳纤维(CF) 改性, 有效地提高了碳纤维/ 聚芳基乙炔(CF/ PAA) 的层间剪切强度( ILSS) 。采用原子力显微镜(AFM) 以力调制模式对CF/ PAA复合材料横截面进行表面形貌和硬度分布研究, 通过对硬度图像进行统计学分析得到纤维、界面相、基体相硬度分布直方图和线分布图, 对不同涂层、同种涂层不同浓度改性后的复合材料界面相特性进行了比较和研究。结果表明, 不同结构、不同浓度SSO 涂层处理对界面的改性效果不同, 含大有机官能团的笼型倍半硅氧烷(MethacrylisobutylPOSS) 的改性效果好。AFM 分析直观地表明, 经不同结构SSO 涂层处理后CF/ PAA 复合材料中出现不同形貌结构、不同硬度的界面过渡层,该界面层提高纤维/ 树脂的粘接。      

IBAD钼膜与Al_2O_3(0001)单晶界面的HREM研究

采用中等能量离子束辅助沉积（IBAD）技术在单晶Al2O3（0001）基片上沉积钼膜，通过HREM等分析手段，在原子尺度上，对于钼膜及其与Al2O3单晶基体界面的显微结构进行了研究。结果表明：钼膜的晶粒呈细小柱状或纤维状，平均晶粒尺寸约为8nm，钼膜的致密度较高，膜内存在非晶组织。在钼膜与Al2O3单晶基片之间存在厚约10～15nm的非晶过渡层，在界面处未发现原子的长程扩散。非晶过渡层与钼膜界面处存在台阶，增加了钼膜的形核点。     

Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and manganese in AA7075 and AA5083 alloys is much more than AA6060 one, the AA6060 aluminum exhibits negligible corrosion rate. Alloying aluminum with other elements and modifying the composition of the electrolyte is a necessary condition for reducing the self-corrosion of the aluminum anodes, whereas the proportion of the amount of additive elements is sufficient and important condition. As AA6060 with a low amount of Zn and Mg, but the high value of the ratio of (Mg/Zn) content (>400) can serve as a good galvanic anode in the alkaline media.     

Characterization of the dielectric properties of covalently attached organic films on silicon surfaces

Monolayers of methyl-undecanoate were constructed on silicon surfaces via a covalent Si-C bond. The molecular monolayers were characterized by high resolution electrical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and ellipsometry and displayed a densely packed monolayer. After formation of the monolayer, the methyl ester was hydrolyzed without noticeable change in the integrity of the monolayer. The carboxyl terminated organic layer was then reacted with (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide to form active N-hydroxy succinimide ester groups. The activation chemistry was confirmed by XPS and the substructure of the methyl-undecanoate carboxylic acid and the N-hydroxy succinimide ester terminated films were characterized using EIS. XPS and EIS spectra provided information on the chemical composition and substructure of the monolayers for each step in the chemical modification of the surface.