硫酸钠溶液中2024—T3铝合金孔蚀过程的电化学噪声特征

高强度航空铝合金结构材料2024-T3在3.0%（质量分数（Na2SO4溶液中发生局部腐蚀的过程中,电位噪声的谱功率密度（SPD）曲线都具有相同的特征,即在极低频下为白噪声,随着频率的升高逐渐转化为1/f^α噪声,相应于一个噪声信号波,有一个腐蚀孔出现,在孔蚀诱导期,白噪声水平升高,截止频率增大,SPD曲线的倾斜段直线斜率小于-20dBv/decade,且趋于增大,孔蚀发生后,上述3个参量则各自朝着上述方向的塑方向变化,孔蚀时的Hurst指数（H）小于非孔蚀期的Hurst指数,而孔蚀时的系统分维（D）则大于非孔蚀期的系统分维。     

Corrosion protection of AA 2024-T3 by bis-[3-(triethoxysilyl)propyl]tetrasulfide in neutral sodium chloride solution. Part 1: corrosion of AA 2024-T3

This study consists of two parts. In the first part, the corrosion of 2024-T3 aluminum alloy (AA 2024-T3) was studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that the anodic S phase (Al₂CuMg) particles dealloyed Al and Mg during the 3.5 h of immersion in a neutral 0.6 M sodium chloride (NaCl) solution; with the dealloying of Mg being the most severe. Simultaneously, a heavy dissolution was also observed for the surrounding Al matrix of the S phase particles. This Al dissolution is likely to be caused by a local alkalization resulting from the coupled cathodic reaction (water and/or oxygen reduction). Such corrosion in AA 2024-T3, however, can be inhibited efficiently after the treatment of bis-[3-(triethoxysilyl)propyl]tetrasulfide (bis-sulfur silane). The associated studies on bis-sulfur silane treated AA 2024-T3 will be presented in the second part.     

2024Al与SiC_p/2024Al复合材料的腐蚀与腐蚀控制研究

用电化学方法和腐蚀失重法研究了 ２０２４Ａｌ和ＳｉＣｐ／２０２４Ａｌ复合材料在 ３．５％ＮａＣｌ水溶液中的耐蚀性,用电化学阻 抗技术对它们的硫酸阳极氧化膜保护性进行了跟踪评价．结果表明ＳｉＣｐ／２０２４Ａｌ在 ３．５％ＮａＣｌ水溶液中比 ２０２４Ａｌ有较大的 腐蚀敏感性．２０２４Ａｌ表面的阳极氧化膜,经热水封闭后,可提供相当好的保护作用．热水封闭的Ｓｉｐ／２０２４Ａｌ阳极氧化膜, 具有良好的耐 ＮａＣｌ溶液腐蚀能力,由于氧化膜中ＳｉＣ颗粒的存在破坏了氧化膜的完整性和均匀性,故其耐蚀性不如 ２０２４ Ａｌ 合金的阳极氧化膜．     

Analysis of corrosion behavior of LY12 in sodium chloride solution with wavelet transform technique

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｔｕｄｙｏｆｓｐｏｎｔａｎｅｏｕｓｃｕｒｒｅｎｔｏｒｐｏｔｅｎｔｉａｌｆｌｕｃ ｔｕａｔｉｏｎｓ,ｗｈｉｃｈｈａｓｂｅｅｎｄｅｓｉｇｎａｔｅｄａｓｅｌｅｃｔｒｏｃｈｅｍｉｃａｌｎｏｉｓｅ(ＥＮ) ,ｆｏｒｔｈｅｃｈａｒａｃｔｅ     

SiCp/2024Al基复合材料的点蚀行为

采用动电位阳极极化法对17%SiCp/2024Al基复合材料及其基体合金在3.5%NaCl水溶液中的耐蚀性进行了研究.结果表明:SiC颗粒的加入并不影响SiCp/2024Al基复合材料的点蚀敏感性,但与基体相比,其耐蚀性有所下降.对极化后和长期浸泡试样的腐蚀形貌观察发现:与基体相比,SiCp/2024Al基复合材料表面上的蚀孔数量相对较多,蚀孔尺寸稍小,大小分布不均匀;最大蚀孔较深,并有严重的裂缝腐蚀;裂缝腐蚀的存在会使SiCp/2024Al基复合材料的点蚀抗力明显降低.能谱分析表明:SiCp/2024Al基复合材料的腐蚀机制为富Cu阴极相与贫Cu阳极相间的电偶腐蚀,另外,SiC与Al间也存在电偶腐蚀倾向.     

Corrosion behavior of aluminum alloy 2024-T3 by 8-hydroxy-quinoline and its derivative in 3.5% chloride solution

The corrosion behavior of aluminum alloy 2024-T3 was studied in 3.5% NaCl solutinn with two fluorescence quinoline compounds named 8-hydroxy-quinoline（8HQ） and 8-hydroxy-quinoline-5-sulfonic acid（HQS）. The open circuit potential（OCP） test result indicates that both compounds change the alloy corrosion potential by adsorbing on the electrode surface. Polarization measurements show that 8HQ is a mixed type inhibitor by blocking the active sites of the metal surface, while HQS is a corrosion accelerator by activating the cathodic reaction. Changes of the impedance parameters in the electrochemical impedance spectroscopy（EIS） are related to the adsorption of 8HQ on the metal surface, which leads to the formation of a protective layer. The impedance diagram in the solution with HQS is similar to the one without additional organic compounds. The morphology and composition of the protective layer were studied by using SEM/EDS. The result confirms the function of the additions that the effect of 8HQ is due to the insoluble aluminum chelate, AI（HQ）3, to prevent adsorption of chloride ion, while the effect of HQS is to break down the oxide film.     

Synergistic effect of pH and oxalate concentration on corrosion of aluminium alloy 2024-T3

This work aims at obtaining comprehensive information on the corrosion behaviour of AA2024-T3 in oxalic acid solutions under different concentrations (0.007–0.2?M) and pH (2–6). Various tests to characterise the corrosion behaviour are performed, including weight loss and electrochemical tests. Coupon surfaces are examined using infinite-focus microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy. Corrosion rates, anodic and cathodic reaction kinetics are detailed to provide a fundamental understanding of the electrochemical behaviour of AA2024-T3 as a function of pH and oxalate concentration. The synergistic effect of pH and oxalate concentration on corrosion of AA2024-T3 is evaluated for both AA2024-T3 matrix and main intermetallics (i.e. Al–Cu–Mg and Al–Cu–Fe–Mn) and the electrochemical behaviour of each constituent element in AA2024-T3 is systematically studied.     

SiC_p/2024Al复合材料阳极氧化膜耐蚀性的电化学阻抗研究

采用电化学阻抗技术研究了碳化硅颗粒增强 ２０２４铝基复合材料（ＳｉＣｐ／２０２４Ａｌ）硫酸阳极氧化膜在 ３．５％ＮａＣｌ水 溶液中的耐蚀性;作为比较,对 ２０２４ Ａｌ的阳极氧化膜耐蚀性也进行了研究 结果表明,ＳｉＣｐ／２０２４Ａｌ复合材料的阳极氧化膜 具有良好的耐 ＮａＣｌ溶液腐蚀的能力,而且重铬酸盐封闭比热水封闭的阳极氧化膜耐蚀性更好．由于氧化膜中出ＳｉＣ颗粒的存在破 坏了氧化膜的完整性和均匀性,故复合材料阳极氧化膜的耐蚀性不如 ２０２４ Ａｌ合金．     

Al2O3p/2024Al基复合材料的界面结构

利用TEM、HRTEM等分析测试手段,对挤压铸造法制备的Al2O3颗粒增强2024Al基复合材料的界面组织结构进行了观察与分析。结果表明：Al2O3p/2024Al基复合材料的界面结合良好,未发现界面反应物,铝基体与Al2O3颗粒以共格关系结合,界面属直接结合型,且Al2O3颗粒与Al基体存在如下的位向关系：Al2O3（1^-1^-21^-）//Al（1^-1^-1^-）;Al2O3〈3^-41^-1^-〉//Al〈110〉。     

Statistical evaluation of EIS and ENM data collected for monitoring corrosion barrier properties of organic coatings on Al-2024-T3

This paper describes the statistical treatment of electrochemical noise (electrochemical noise methods, ENM) and impedance (electrochemical impedance spectroscopy, EIS) data collected for corrosion monitoring of epoxy coated aluminum 2024-T3. The epoxy was applied using electrodeposition to Al-2024-T3 panels treated with one of three surface pretreatments. Six coating systems were prepared by varying the electrodeposition parameters and the pretreatment. Linear regression analysis of the data was used to detect the individual contributions relating to the analysis technique, topcoat application and pretreatment type. As a result of the statistical treatment it was found that EIS data has significantly less variance compared to ENM data, that EIS data can be used to differentiate the effects generated from the coating and pretreatment, and that ENM data cannot be used to differentiate the effects generated from the coating and pretreatment due to the high variance in data values associated with ENM. None of this information could be quantified without the statistical treatment.     

Nondestructive analysis of pitting corrosion characteristics on EN AW-2024-T3 using 3D optical pattern profilometry

High-strength age-hardenable aluminium alloys are susceptible to localised corrosion. It is vital to monitor the evolution of the corrosion depth in order to prevent a critical degradation of the mechanical properties. This study presents the application of 3D optical pattern profilometry for the analysis of the pitting corrosion behaviour of the aluminium alloy EN AW-2024-T3. Therefore, measurements were conducted using a 1?M NaCl solution at different exposure times. The measurements are compared to the results of optical microscopy investigations of metallographic specimens as well as laser scanning microscopy measurements. In immersion bath tests, the 3D pattern profilometry shows a high measurement accuracy of the pitting corrosion. Regarding the pit characteristics, corroded metal sheets exhibit an increase in the pit depth, volume and area with an increasing exposure time of up to 312?h and then decrease. Moreover, a higher increase in the width in rolling direction than perpendicular to it is noticeable.     

Anodising of Al 2024-T3 in a modified sulphuric acid/boric acid bath for aeronautical applications

A novel borate/boric/sulphuric acid anodising process is studied. The results show that the physical structure of the films is influenced not only by the bath used, but also and mainly by the substrate, i.e., Al 2024-T3 or Al. The corrosion resistance of the anodised specimens is satisfactory for practical applications and the fatigue resistance is not significantly different from that obtained with the traditional chromic acid anodising.     

Effects of applied potential and solution temperature on the pitting corrosion of pure aluminium in sulphate ion-containing chloride solution

Effects of applied potential and solution temperatureT _s on the pitting corrosion of pure aluminium (Al) were investigated in 0.01 M NaCl solutions containing various sulphate (SO₄ ^2-) ion concentrations using a potentiodynamic polarisation experiment, the potentiostatic current transient technique, ac impedance spectroscopy and atomic force microscopy (AFM). The potentiodynamic polarisation curves showed a rise in the pitting potentialE _pir values and a simultaneous increase in anodic current density at potentials much higher than theE _pit value as the SO42~ ion concentration increases. This implies that (SO₄ ^2-) ions impede pit initiation at potentials belowE _pit but enhance pit growth aboveE _pit. This was confirmed from the larger pit growth rate parameterb values of pure Al exposed to (SO₄ ^2-) ion-containing chloride solutions during the abrading action than those exposed to (SO₄ ^2-) ion-free chloride solution. Furthermore, at 7_s=25°C, the charge densityQ values for the Al metal dissolution in the presence of (SO₄ ^2-) ions were smaller than the value in its absence. By contrast, as validated by the capacitance values and the AFM images of the re-anodized specimens, an enhanced metal dissolution was observed in (SO₄ ^2-) ion-containing chloride solutions at 7_s=60° and 80°C. From the experimental findings, it is suggested that (SO₄ ^2-) ions act as inhibitors of pitting corrosion on pure Al belowE _pit and at 7_s=25°C, whereas they act as promoters at 7_s=60 ° and 80°C. This originates from the accelerated dissolution of the bare metal extensively exposed to the temperature-sensitive Cl ion attack, which occurs at potentials aboveE _pit     

LC4铝合金在氯化钠溶液中的孔蚀特征

LC4铝合金在 2 .0 %NaCl溶液中发生局部腐蚀的过程中 ,电位噪声的谱功率密度 (SPD)曲线具有相同的特征 ,即在极低频下为白噪声 ,随着频率的升高逐渐转化为 1/fa 噪声 ,相应于一个噪声信号波 ,有一个腐蚀孔出现。在孔蚀诱导期 ,白噪声水平升高 ,截止频率增大 ,SPD曲线的倾斜段直线斜率小于 - 2 5dBv/Hz ,且趋于增大。孔蚀发生后 ,上述 3个参量则各自朝着上述方向的逆方向变化。实验发现 ,孔蚀参数SE 和SG 可以正确的表征孔蚀的发生、发展及材料的均匀腐蚀。阻抗测量结果表明 :孔电阻在刚开始浸泡时较大 ,随后减少渐趋于平稳 ,最后孔电阻又升高。这是因为随着浸泡时间的增加 ,孔面积渐渐增大 ,浸泡 6 5 0 0 0min时 ,孔电阻有所上升 ,可能是由于母孔内子孔的形成所致。产物电阻逐渐稳定上升 ,表明腐蚀产物逐渐增多。     

Emulation and study of the corrosion behavior of Al alloy 2024-T3 using a wire beam electrode (WBE) in conjunction with scanning vibrating electrode technique (SVET)

When a metal substrate surface is metallurgically non-uniform, heterogeneous electrochemical processes occur. The wire beam electrode (WBE) is a multi-piece electrode constructed with a variable number of metal wires embedded in insulating material. Each wire surface is much smaller than the total electrode surface, and for most purposes its corrosion and other electrochemical parameters can be assumed to be uniform even if the process on the whole electrode surface is not. With this assumption, all the electrochemical theories based on a uniform corroding surface and on uniform electrochemical processes can be applied to individual wires on the surface of a WBE. Two different types of WBE’s have been built with the intention of emulating the behavior of a heterogeneous aluminum alloy surface and have been used to extract the electrochemical noise resistance (R_n). A new approach is the use of a 9-wire WBE where the current density at the surface is detected by the scanning vibrating electrode technique (SVET). The ability of SVET to obtain data with small spatial resolution is used to understand if the WBE configuration can simulate the behavior of a plate electrode. From the data obtained thus far, the WBE configuration showed the ability to emulate a continuous surface as the current distributions from the analysis with the SVET has been confirmed.     

Effect of Schiff base as corrosion inhibitor on AZ31 magnesium alloy in hydrochloric acid solution

Schiff base derived from the condensation reaction of analar grade 1-amino-2-naphthol 4-sulphonic acid with cinnamaldehyde was prepared under microwave condition. The Schiff base was analysed by infrared spectroscopy. This Schiff base as a corrosion inhibitor of AZ31 magnesium alloy in 0.05 mol/L HCl solution was studied. The inhibition effect of the Schiff base compound (4Z)-4-(3-phenyl allylidene amino)-3-hydroxy naphthalene-1-sulfonic acid (AC) on AZ31 magnesium alloy corrosion was studied using mass loss, potentiodynamic polarization technique, electrochemical impedance spectroscopy methods. The potentiodynamic polarization curve shows that Schiff base AC inhibits both anodic and cathodic reactions at all concentration, which indicates it is a mixed type inhibitor. EIS results indicate that as the additive concentration is increased, the polarization resistance increases whereas double-layer capacitance decreases. The adsorption of AC on the AZ31 magnesium alloy surface in 0.05 mol/L HCl obeys the Langmuir adsorption isotherm.     

2024-T3铝合金在硫酸-硼酸-磷酸中的阳极氧化和腐蚀行为

在含有10%硫酸、5%硼酸和2%磷酸的混合电解液中,对2024-T3铝合金进行阳极氧化处理,以提高其耐腐蚀性能。使用电化学阻抗频谱分析研究阳极氧化处理后合金的腐蚀行为。利用塔菲尔图和盐水喷雾技术进行对比发现,与只用磷酸或硫酸和硼酸的电解液相比,使用含有10%硫酸、5%硼酸和2%磷酸的混合电解液阳极氧化处理后的2024-T3铝合金,具有更好的耐腐蚀性和持久性。该电解液可以替代普遍用于阳极氧化铝合金的铬酸盐浴。     

SiC_p/2024Al铝基复合材料的耐蚀性

用电化学方法和浸泡试验研究了SiC颗粒粒度和体积分数对SiCp/ 2 0 2 4Al铝基复合材料在 3.5 %NaCl水溶液中耐蚀性的影响 ,作为比较对 2 0 2 4Al的耐蚀性也进行了研究。结果表明 ,与基体相比 ,SiCp/ 2 0 2 4Al复合材料并不增加点蚀敏感性 ,其抗蚀性与SiC体积分数和粒度有关 ,SiC颗粒体积分数低或粒度高的复合材料 ,其抗蚀性往往大。     

WC_p/2024Al基复合材料的腐蚀机理

采用动电位阳极极化法对体积分数为11.4%WCp/2024Al基复合材料及其基体合金在3.5%NaCl水溶液中的耐蚀性能进行研究。结果表明,由于WC颗粒的加入,提高了WCp/2024Al基复合材料的腐蚀速度。通过对恒电位极化后试样观察发现,WCp/2024Al基复合材料腐蚀机理为富Cu相作为阴极区与其周围的贫Cu区作为阳极区构成电偶腐蚀以及WC颗粒与基体间的协同腐蚀作用。这种双重的电偶腐蚀致使复合材料腐蚀速度加快。