中国腐蚀与防护学报, 2017, 37(3): 273-278
doi: 10.11902/1005.4537.2016.027
铝合金阳极氧化层在江津污染大气环境中暴露腐蚀行为研究

Atmospheric Corrosion of Anodized Pure Al 1060, Al-alloys 2A12 and 7A04 Exposed to Polluted Atmospheric Environment at Jiangjin Region
周和荣, 胡碧华, 姚望, 洪新培, 宋述鹏

摘要:

采用扫描电镜、能谱和X射线衍射仪以及腐蚀失重等分析测试方法研究了1060纯Al、2A12和7A04铝合金表面阳极氧化膜层在江津工业大气环境中的暴晒腐蚀行为。结果表明,1060纯Al、2A12和7A04铝合金阳极氧化膜层失重与暴露时间的关系符合幂函数规律;随腐蚀时间的延长,腐蚀产物不断增多,失重增大。3种铝材腐蚀严重程度顺序由大到小依次为:2A12铝合金>7A04铝合金>1060纯Al。腐蚀产物呈团状和块状形貌,主要由Al2O3、Al(OH)3和硫酸铝水合物组成。3种铝材除去表面腐蚀产物的阳极氧化膜层损伤和腐蚀坑数量差别明显,腐蚀机制为Al2O3在酸性介质中的溶解。

关键词: 铝合金 ; 阳极氧化膜 ; 江津 ; 工业污染大气 ; 暴露实验

Abstract:

The atmospheric corrosion behavior of anodized pure Al 1060 as well as Al-alloys 2A12 and 7A04 exposed for 24 months in atmosphere with pollutants at Jiangjin region was investigated by mass loss method, scanning electron microscope (SEM), energy dispersive X-ray detector (EDS) and X-ray diffractometer (XRD). The results show that the relation of mass loss versus time (h) accords with power function law as C=At n. In other words, the corrosion product is increasing with testing time. The order of corrosion severity of the tested materials can be ranked as the following order 2A12 alloy>7A04 alloy>1060. The corrosion products show agglomerate structure composited of Al2O3,Al(OH)3 and aluminum sulfate hydrate. After removing the surface corrosion products, clear difference in the damage manner and the quantity of corrosion pits can be observed for the three anodic oxidation films. The corrosion mechanism may be ascribed to the dissolution of alumina in certain acidic medium.

Key words: aluminum alloy ; anodizing film ; Jiangjin region ; industrial polluted atmosphere ; exposure test

Al及铝合金由于具有密度小、力学性能优异、导电与导热能力强、成型加工性好以及物理化学综合性能好等一系列优点,被大量用于制造飞机机体和运载火箭箭体结构,是航空航天工业的主要结构材料,同时在交通、能源、食品、电子等领域得到广泛的应用,已经成为工业中使用量仅次于钢铁的第二大金属材料[1-3]。为了降低Al及铝合金在自然大气环境中的腐蚀速率,常常采用阳极氧化防护。但在自然大气环境中,由于腐蚀性环境介质的影响,常常引起铝合金阳极氧化膜失效。研究阳极氧化膜的失效过程以及失效机制成为大气腐蚀的重要课题之一。

自然环境下的户外暴露实验能反映现场实际情况,所得的数据直观、可靠,可以获得户外自然环境下材料的腐蚀特征和腐蚀规律,评价金属材料、非金属材料、覆盖层和防锈包装等在户外条件下的耐蚀性能,评估实验环境下金属的使用寿命,为合理选材、有效设计和产品防护标准提供依据[2-5]。材料大气腐蚀受气象和污染因素的影响,许多研究[5-12]显示工业污染大气环境中S的污染物是重要的大气腐蚀介质。

Al及铝合金在工业污染大气环境中腐蚀数据的积累受到许多国家的高度重视,积累了大量的腐蚀数据,总结了腐蚀规律[1,13-21]。如Oesch等[16]研究了纯Al在SO2气体环境中的腐蚀动力学,其腐蚀产物为Al3(SO4)2(OH)59H2O和Al2(SO4)216H2O;Liao等[19]研究了Al的点蚀行为;Bengtsson等[21]研究了CO2和NaCl对纯Al腐蚀的影响。但在铝合金部件加工处理工艺中,纯Al、铝合金2A12(T4) 和7A04(T6) 常常采用硫酸阳极氧化和封闭处理以提高铝合金材料的耐蚀性。为了更加实际地研究铝合金材料在我国工业污染大气环境中的腐蚀行为,国家材料大气腐蚀试验网站对铝合金材料裸材、阳极氧化处理和涂层在江津大气暴晒实验站开展了持续腐蚀数据积累。在我国,典型的工业污染大气环境为江津地区的酸雨环境。因此,本课题主要研究Al及铝合金经阳极氧化处理后在我国典型工业污染大气环境 (江津自然大气环境) 中的腐蚀行为,了解腐蚀产物形成过程,分析腐蚀动力学规律,研究对于评估Al及铝合金耐大气腐蚀寿命具有参考价值。

1 实验方法

3种实验材料的化学成分 (质量分数,%) 见表1。试样尺寸为100 mm×50 mm×3.0 mm。所有试样经硫酸阳极氧化处理后采用沸水封闭处理,膜层性能和厚度符合工艺要求并检测合格。经硫酸阳极氧化处理后的试样放入干燥器内待用。

大气暴晒实验方法按照国标GB/T14165-2008 《金属和合金大气腐蚀试验现场试验的一般要求》执行,实验地点为江津大气暴晒试验站,实验周期为24个月,取样周期为1,3,6,12和24个月。每组取4块平行试样,其中3块试样测量质量损失,精确到0.1 mg。用50 mL H3PO4+20 g CrO3+1 L蒸馏水配成溶液去除腐蚀产物后,再放入浓HNO3溶液中浸泡5 min除去残余的腐蚀产物。采用扫描电子显微镜 (SEM,Nova nano 400) 观察腐蚀产物的微观形貌,并用能谱仪 (EDS,Penta FETX-3Si(Li)) 分析腐蚀产物的成分。

表1 纯Al及铝合金的化学成分
Table 1 Chemical compositions of Al and two Al alloys(mass fraction / %)
Material Si Fe Cu Mn Mg Zn Ti Al
1060 0.061 0.36 0.02 0.02 0.02 0.005 --- Bal.
2A12 0.13 0.35 4.68 0.53 1.58 0.10 0.023 Bal.
7A04 0.068 0.42 1.51 0.24 2.62 5.99 0.015 Bal.

表1 纯Al及铝合金的化学成分

Table 1 Chemical compositions of Al and two Al alloys(mass fraction / %)

2 结果与讨论
2.1 腐蚀动力学

图1为经阳极氧化后的1060纯Al、2A12和7A04铝合金在江津大气试验站室外暴晒失重与暴露时间的关系曲线。结果表明,随腐蚀时间延长,失重数值呈增长趋势;其中1060纯Al失重较小,7A04铝合金失重较大,2A12铝合金失重最大。

图1 经阳极氧化的1060纯Al、2A12和7A04铝合金在江津大气试验站失重与暴露时间的关系曲线

Fig.1 Mass losses of anodized 1060, 2A12 and 7A04 alloys during exposure in Jiangjin atmospheric environment

图1中数据进行拟合,结果见表2。可见,失重与暴露时间的关系符合幂函数规律,即:

C = A t n (1)

式中,C为腐蚀失重,g/cm2;t为暴露时间,月;An为常数。A值近似代表第1月的腐蚀失重量,A值越大腐蚀越严重;n值代表了腐蚀发展的趋势,n值越小,腐蚀减缓的趋势越大。3种铝材失重数据拟合结果为:A1060<A7A04<A2A12,n1060<n2A12<n7A04<1,说明3种铝材阳极氧化膜在江津自然大气环境中暴晒后,其腐蚀严重程度顺序由大到小依次为2A12铝合金>7A04铝合金>1060纯Al。幂指数n在0.79~0.95,变化范围较大,可能与3种铝材经阳极氧化处理后表面状态不同有关。

表2 式 (1) 中An的拟合数据
Table 2 Fitting results of A and n in Eq.(1)
Material A n
1060 0.66 0.86
7A04 0.82 0.95
2A12 1.67 0.79

表2 式 (1) 中An的拟合数据

Table 2 Fitting results of A and n in Eq.(1)

2.2 阳极氧化膜宏观腐蚀形貌

表面经阳极氧化预处理的1060,2A12和7A04 3种铝材在江津自然大气环境中暴晒后的腐蚀宏观形貌见图2。暴晒1个月后,3种铝材的宏观形貌没有明显变化;暴晒12个月后表面沉积了少量腐蚀产物和灰尘,表面颜色由灰色变为灰绿色;暴晒24个月后试样中部沉积了较多腐蚀产物和灰尘,表面颜色由灰绿色变为灰黑色。

图2 阳极氧化预处理的1060纯Al,7A04铝合金和2A12铝合金在江津大气环境中暴晒不同时间后的宏观腐蚀形貌

Fig.2 Corrosion images of anodized 1060 aluminium (a, b, c) 7A04 Al-based (d, e, f) and 2A12 Al-based (g, h, i) alloys after exposure in Jiangjin atmospheric environment for 1 month (a, d, g), 12 months (b, e, h) and 24 months (c, f, i)

2.3 腐蚀产物形貌和EDS分析

经阳极氧化的1060,2A12和7A04 3种铝材在江津自然大气环境中暴晒24个月后表面微观形貌见图3。1060纯Al表面氧化膜凹凸不平,部分区域出现块状脱落 (图3a);放大后看出,表面氧化膜出现明显坑状和片状脱落,阳极氧化膜表面出现数量较多的裂纹,腐蚀产物呈团状或块状 (图3b)。7A04铝合金表面沉积少量分散的腐蚀产物,腐蚀产物呈不规则的团状 (图3c);放大后看出,表面氧化膜有明显孔洞和块状脱落,阳极氧化膜出现数量较多的龟裂,氧化膜呈块状覆盖在试样表面,部分区域沉积的腐蚀产物呈团絮状 (图3d)。2A12铝合金表面沉积少量分散的腐蚀产物,腐蚀产物呈不规则形状 (图3e),腐蚀产物放大后呈层状分布,底层氧化膜呈块状,有明显龟裂和孔洞,腐蚀产物堆积在氧化物表面,呈不规则形状 (图3f)。对表面突出腐蚀产物 (图3f) 进行EDS分析,表明腐蚀产物含有Al,O,Si和S (见图4)。因此推断,带阳极氧化膜的2A12铝合金暴晒过程中,主要发生Al和Al2O3在含SO42-和SO32-酸性溶液中的溶解腐蚀过程,故腐蚀产物主要为Al2O3、Al(OH)3和硫酸铝水合物[16,17]

图3 阳极氧化预处理的1060纯Al,2A12和7A04铝合金在江津大气环境中暴晒24个月后的表面微观形貌

Fig.3 SEM images of anodized 1060 (a, b), 2A12 (c, d) and 7A04 (e, f) alloys after exposed in Jiangjin atmospheric environment for 24 months

图4 图3f中1-2位置处腐蚀产物的EDS分析

Fig.4 EDS line-scanning results from point 1 to point 2 in Fig.3f: (a) O, (b) Al, (c) Si and (d) S

2.4 除去腐蚀产物后表面形貌分析

阳极氧化预处理的1060纯Al、2A12和7A04铝合金在江津自然大气环境中暴晒24个月后,除去表面腐蚀产物后的微观形貌见图5。1060纯Al、2A12和7A04铝合金表面形貌差别明显,1060纯Al表面较完整,有少量腐蚀坑,表面局部区域有氧化膜减薄,尺寸较大的坑较少 (图5a和b);7A04铝合金表面有明显密集分布的腐蚀坑,局部坑扩展为孔洞,为明显点蚀形貌,氧化膜出现明显裂纹 (图5c和d); 2A12铝合金表面有数量众多的腐蚀坑,局部坑扩展为孔洞,部分孔洞尺寸比7A04铝合金的表面孔洞大,点蚀明显,氧化膜层出现众多裂纹和损伤 (图5e和f)。对图5f中点蚀坑ab位置进行EDS分析 (图6),在坑边缘和中心未见Cu和Mg存在,显示试样表面 (含腐蚀坑) 的Cu和Mg发生溶解;Al的含量出现较大幅度波动,主要是Al2O3中Al含量较少,而基体Al含量较高的缘故。

图5 阳极氧化预处理的1060纯Al、2A12和7A04铝合金在江津站暴晒24个月并除去腐蚀产物后的形貌

Fig.5 SEM images of anodized 1060 (a, b), 2A12 (c, d) and 7A04 (e, f) alloys after exposure in Jiangjin atmospheric environment for 24 months and then removing corrosion products

实验结果表明,1060纯Al、2A12和7A04铝合金表面阳极氧化膜层的失效首先从表面吸附开始。由于试样长期暴露于工业自然大气环境中,表面容易富集灰尘或雨水中的杂质 (从宏观腐蚀形貌可以看出) ,富集的灰层或杂质吸附水使材料表面长期处于潮湿状态。由于我国江津地区属于典型的工业污染大气环境,环境中含有浓度较高的SO2等腐蚀性介质 (如重庆地区2013年空气中PM10、PM2.5、SO2、NO2的年均浓度分别为106,70,32和38 μg/m3;降水pH值年均为4.86,资料来源于《2014年重庆市环境质量简报》),且阳极氧化膜属于多孔结构,SO2很容易吸附沉积到试样表面使表面薄液膜呈酸性。吸附的SO2在表面发生如下反应[8,16,17]

S O 2 ( ads ) + H 2 O H 2 S O 3 (2)

H 2 S O 3 H + ( ads ) + HS O 3 - (3)

HS O 3 - + [ O ] HS O 4 - (4)

HS O 4 - H + ( ads ) + S O 4 2 - (5)

而依据Al的电位-pH值图,铝合金表面形成的Al2O3膜在酸性介质中容易发生溶解反应,以及形成硫酸盐腐蚀产物,具体化学反应式为:

A l 2 O 3 + 6 H + 2 A l 3 + + 3 H 2 O (6)

2 A l 3 + + 3 S O 4 2 - + 14 H 2 O A l 2 S O 4 ) 3 14 H 2 O (7)

由于试样材料表面吸附位置的差异、阳极氧化膜缺陷以及SO2溶解量不同,不同铝合金阳极氧化膜腐蚀差异程度较大。由于局部阳极氧化膜发生溶解后腐蚀至铝合金基体,腐蚀溶解会进一步深入且腐蚀坑面积扩大,导致出现点蚀坑。

由于3种铝材的成分不同,导致表面阳极氧化膜的结构出现差异。纯Al由于合金元素含量低,阳极氧化膜结构缺陷少,因此其腐蚀程度很轻,腐蚀产物较少,阳极氧化膜较好地保护了基体;而铝合金2A12和7A04由于阳极氧化膜存在较多的缺陷,因此出现了较多的腐蚀产物和点蚀坑,且阳极氧化膜出现龟裂,腐蚀坑数量多,局部点蚀坑面积较大。阳极氧化膜的腐蚀首先由于SO2吸附在缺陷位置形成腐蚀起源点,阳极氧化膜逐渐溶解形成点蚀,点蚀坑不断溶解扩展为剥蚀。

图6 图5f点蚀坑a-b位置EDS分析

Fig.6 EDS line-scanning results along the line a-b inFig.5f: (a) Al, (b) Cu, (c) Mg

3 结论

(1) 阳极氧化预处理的1060纯Al、2A12和7A04铝合金在江津自然大气环境中暴晒失重与时间的关系符合幂函数规律 (C=Atn),按腐蚀严重程度由大到小排列顺序为:2A12>7A04>1060。

(2) 阳极氧化预处理的3种铝材表面腐蚀产物随暴晒时间的延长不断增多,腐蚀产物呈团状或块状。

(3) 阳极氧化预处理的3种铝材暴晒24个月后,表面阳极氧化膜层损伤和腐蚀坑数目差别明显,Al含量在腐蚀坑边缘和中心差异明显。

(4) 铝合金表面阳极氧化膜在江津工业污染大气环境中的腐蚀机制主要是Al2O3在酸性介质中的溶解,主要形式是点蚀,并随暴露实验的进行发展为剥蚀。

The authors have declared that no competing interests exist.

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DOI:10.1016/S0010-938X(99)00005-0      URL     [本文引用:2]
[6] Zhou H R, Li X G, Ma J, et al.Dependence of the corrosion behavior of aluminum alloy 7075 on the thin electrolyte layers[J]. Mater. Sci. Eng., 2009, B162: 1
The corrosion behavior of aluminum alloy 7075-T6 dependent of the thin electrolyte layers in 102M sodium sulfate solution has been investigated using cathodic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The oxygen reduction current is measured to be maximum at 611.102V by cathodic polarization test when the thickness of the electrolyte layer is 11002μm. The EIS results show that the corrosion rate increases with the increase of the immersing time independent of thickness of the electrolyte layer although 11002μm thick electrolyte layer produces the largest corrosion rate over the immersing time between 002h and 9602h. However, with the longer immersing time, corrosion rate of the sample in bulk solution becomes higher. This result can be explained that the diffusion of the corrosion product and the metal ions from the electrode in the case of the thicker layer is easier. SEM morphologies reveal that corrosion products on the surface of the samples are distributed unhomogenously, with their amount near edges being more than the center area. In addition, XPS analysis demonstrates that corrosion products are mainly composed of Al(OH) 3 and Al 2 (SO 4 ) 3 .
DOI:10.1016/j.mseb.2009.01.003      URL     [本文引用:]
[7] Zhang X Y, An B G, Han E-H, et al.Runoff and corrosion of material due to acid rain[J]. Corros. Sci. Prot. Technol., 2002, 14: 157
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(张学元, 安百刚, 韩恩厚. 酸雨对材料的腐蚀/冲刷研究现状[J]. 腐蚀科学与防护技术, 2002, 14: 157)
阐述了全球和我国酸性降雨分布、酸雨给人类带来的危害及损失、酸雨对无机材料、有机涂层、金属材料的腐蚀/冲刷影响的研究现状,总结了酸雨对材料腐蚀行为的研究方法.
[8] Zhou H R, Li X G, Dong C F, et al.Corrosion behaviors of aluminum alloys in simulated SO2 pollute atmosphere[J]. J. Aeronaut. Mater., 2008, 28(2): 39
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(周和荣, 李晓刚, 董超芳. 铝合金在模拟SO2污染大气环境中的腐蚀行为[J]. 航空材料学报, 2008, 28(2): 39)
采用扫描电镜(SEM/EDX)、增重法、傅立叶变换红外光谱(FTIR)和X射线衍射研究铝合金1060、铝合金2A12和7A04分别在表面沉积与未沉积70μg/cm<sup>2</sup>氯化钠条件下在含50&#215;10<sup>-6</sup>SO<sub>2</sub>(50ppm)污染大气环境中的腐蚀行为和规律,并测试三种材料力学性能的变化。研究结果表明,随试验时间的延长,铝合金表面腐蚀产物不断增多,腐蚀增重符合指数衰减规律<i>Δm/A</i>=<i>B+Dexp(-t/k)</i>,抗拉强度和延伸率呈下降趋势;表面腐蚀产物形貌呈团状或圆团状,并不断向外扩展延伸,呈现不均匀的凹凸形貌;铝合金在50ppm SO<sub>2</sub>污染大气环境中腐蚀产物少,腐蚀增重较少,表面腐蚀产物主要为氧化铝和硫酸铝;而表面沉积70μg/cm<sup>2</sup>NaC l的铝合金在模拟50ppm SO<sub>2</sub>污染大气环境中腐蚀产物明显增多,腐蚀增重大,力学性能下降幅度大,二氧化硫和氯化钠的协同作用明显促进铝合金的腐蚀,腐蚀产物主要为氧化铝、铝的硫酸盐和铝的氯化物。
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[9] Qu Q, Yan C W, Wan Y, et al.Effects of NaCl and SO2 on the initial atmospheric corrosion of zinc[J]. Corros. Sci., 2002, 44: 2789
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[10] Zhou H R, Ma J, Lu Q K, et al.Corrosion study of aluminum alloys in Jiangjin atmospheric environment[J]. Equip. Environ. Eng., 2009, 6(3): 10
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(周和荣, 马坚, 陆启凯. 典型铝合金在江津自然大气环境中的腐蚀行为研究[J]. 装备环境工程, 2009, 6(3) : 10)
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[11] Han W, Wang Z Y, Yu G C, et al.Corrosion of aluminum in wet/dry environment containing SO2[J]. Chin. J. Nonferrous Met., 2003, 13: 631
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(韩薇, 王振尧, 于国才. 铝在含SO2湿润/干燥环境中的腐蚀规律[J]. 中国有色金属学报, 2003, 13: 631)
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[12] Zhou H R, Li X G, Dong C F, et al.Corrosion behavior of aluminium alloys after cyclic wet-dry immersion test in 0.02 mol/L NaHSO3 solution[J]. J. Chin. Soc. Corros. Prot., 2008, 28: 345
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(周和荣, 李晓刚, 董超芳. 铝合金在NaHSO3溶液中干湿周浸腐蚀性能及其行为[J]. 中国腐蚀与防护学报, 2008, 28: 345)
The corrosion behaviors of aluminium alloys 1060,2A12 and 7A04 under cyclic wet-dry immersion conditions have been investigated in 0.02 mol/L sodium sulfite solution by the mass loss method and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was used to observe the surface morphology; energy dispersive X-ray detector (EDX) and X-ray photoelectron spectroscopy (XPS) were employed to analyze the corrosion products. We also tested the mechanical capability of experimental materials. The results showed that corrosion product was increasing with testing hours prolonging, mass loss adding, strength and elongation percentage declining. Surface observation revealed that corrosion product was agglomerated and accidented, extending forth. The main corrosion product is alumina and aluminium sulfate hydrate. The results of EIS indicated that corrosion rate is highest in 360 hour. Corrosion resistance of aluminium 1060 was best in 0.02 mol/L sodium sulfite solution, but that of aluminium alloy 7A04 was worst.
[13] Li J F, Zheng Z Q, Ren W D.Function mechanism of secondary phase on localized corrosion of Al alloy[J]. Mater. Rev., 2005, 19(2): 81
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(李劲风, 郑子樵, 任文达. 第二相在铝合金局部腐蚀中的作用机制[J]. 材料导报, 2005, 19(2): 81)
铝合金中通常含有一些时效析出相及杂质相等第二相粒子,这些第二相粒子对铝合金局部腐蚀行为产生重大影响。概括了析出相θ(Al_2Cu)、η(MgZn_2)、β(Mg_3Al_2)及含 Fe 杂质相 FeAl_3等在铝合金局部腐蚀中的作用机制,重点介绍了 S 相(Al_2CuMg)和 T1相(Al_2CuLi)对铝合金局部腐蚀作用机制的不同观点。
[14] González J A, Morcillo M, Escudero E, et al.Atmospheric corrosion of bare and anodized aluminium in a wide range of environmental conditions, Part I: visual observations and gravimetric results[J]. Surf. Coat. Technol., 2002, 153: 225
This study compares the behaviour of aluminium in the bare condition and when protected with anodic films of approximately 7, 17 and 28 μm thickness for 42 months of exposure in 11 atmospheres of very different aggressivities, with salinity values ranging from between 2.1 and 684 mg Cl 61 m 612 d 611. The anodic films, obtained in a sulfuric acid bath and sealed for 60 min in boiling deionized water, were characterised before and after different exposure times by means of: visual inspection; observation with a magnifying glass; and using classic gravimetric techniques. Optical and electron microscopy were occasionally used with some specimens that showed symptoms of localised corrosion. Aluminium behaves as a passive material in atmospheres of low salinity but exhibits pitting corrosion after 1 year at chloride pollution levels of ≥50 mg Cl 61 m 612 d 611 and after 2 years at levels of ≥10 mg Cl 61 m 612 d 611. Anodising and sealing prevents the risk of pitting corrosion even in the most aggressive atmospheres, except in the case of the coatings of the lowest thickness.
DOI:10.1016/S0257-8972(01)01680-2      URL     [本文引用:]
[15] Mendoza A R, Corvo F.Outdoor and indoor atmospheric corrosion of non-ferrous metals[J]. Corrosi. Sci., 2000, 42: 1123
In the present paper, a study of the atmospheric corrosion of copper, zinc and aluminium exposed on three test sites indoors and outdoors (coastal, urban-industrial and rural) under different exposure conditions up to 18 months is reported. Corrosion results are treated statistically and adjusted to a model previously proposed for steel [A.R. Mendoza, F. Corvo, Corrosion Science 41(1) (1999) 75鈥86.] based on the influence of environmental parameters and main pollutants (SO 2 and chlorides) on the atmospheric corrosion of metals. The interaction between the chloride deposition rate with the time of rainfall (outdoors) and with the time of wetness at temperature between 5掳C and 25掳C (indoors) were found to be the most significant variables influencing the corrosion of the three metals investigated; although other variables appeared to be important in the corrosion process depending on the metal nature. The results obtained confirm and allow us to expand the model previously proposed for steel to non-ferrous metals. A classification of the atmospheric corrosion aggressivity of the test sites based both on environmental data and corrosion rate measurements was made according to ISO 9223. The corrosion aggressivity prognostic of this standard is not always in agreement with the results obtained in Cuban atmospheric conditions.
DOI:10.1016/S0010-938X(99)00135-3      URL     [本文引用:]
[16] Oesch S, Faller M.Environmental effects on materials: The Effect of the Air Pollutants SO2, NO2, NO and O3 on the corrosion of copper, zinc and aluminium. A short literature survey and results of laboratory exposures[J]. Corros. Sci., 1997, 39: 1505
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[17] Graedel T E.Corrosion mechanisms for aluminum exposed to the heat atmosphere[J]. J. Electrochem. Soc., 1989, 136: 204C
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[18] An B G, Zhang X Y, Song S Z, et al.A study of electrochemical impedance spectrum for corrosion behavior of LY12 aluminum alloy in simulated acid rain[J]. J. Chin. Soc. Corros. Prot., 2003, 23: 167
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(安百刚, 张学元, 宋诗哲. LY12铝合金在模拟酸雨溶液中的阻抗谱研究[J]. 中国腐蚀与防护学报, 2003, 23: 167)
利用电化学阻抗谱和极化曲线方法,研究了模拟酸雨溶液pH值对 LY12铝合金腐蚀行为的影响.结果表明,当模拟酸雨溶液pH小于3.1时,LY12铝合金的腐蚀电位随pH值的升高而变负;当溶液pH大于3.4 时,LY12铝合金的腐蚀电位随pH值升高而变正.在pH小于3.4的模拟酸雨溶液中,LY12铝合金的表面膜发生溶解,随着浸泡时间延长,膜厚度降低, 膜阻抗降低,LY12铝合金的腐蚀速率升高.而在pH大于3.8溶液中,LY12铝合金的表面膜厚度基本不随浸泡时间发生明显变化,随浸泡时间增加,膜阻 抗增大,LY12铝合金的腐蚀速率降低.从铝合金表面膜特性和离子吸附及腐蚀产物等方面,对实验结果进行了讨论.
[19] Liao C M, Olive J M, Gao M, et al.In-situ monitoring of pitting corrosion in aluminum alloy 2024[J]. Corrosion, 1998, 54: 451
An in-situ monitoring method was used to observe the initiation sites and the processes of pitting corrosion in aluminum alloy 2024-T3 in real time. These observations complemented more detailed information about composition and distribution of constituent particles, pre- and post-corrosion surface morphology, and the internal morphology of corrosion pits. In-situ observations provided a comprehensive view of the development of localized corrosion in real time. Results confirmed the importance of intermetallic constituent particles in promoting initiation and growth of pits in aluminum alloys. Heterogeneous distribution of these particles served to define the location and extent (or severity) of pitting. A conceptual model was proposed as a framework for continued research. The formation of occluded cells under corrosion product domes over severe pits was observed. This formation will be incorporated into an overall reconsideration and modeling of the processes of pitting corrosion of aluminum alloys.
DOI:10.5006/1.3284873      URL     [本文引用:1]
[20] Neufeld A K, Cole I S.Using Fourier transform infrared analysis to detect corrosion products on the surface of metals exposed to atmospheric conditions[J]. Corrosion, 1997, 53: 788
Fourier Transform Infrared (FTIR) analysis was applied to characterize the surface of atmospherically exposed metal plates. Early stages of atmospheric corrosion result in formation of corrosion films. Corrosion films are made up of layers of corrosion products initially caused from chemical reactions between the metal substrate and adsorbed gases and then by reactions between corrosion products and adsorbed gases. A protocol was developed for analysis of corrosion films in situ on zinc-galvanized and 55% Al-Zn surfaces. Using a variable angle reflectance accessory, modeling, and cautious interpretation, functional groups were deduced from IR absorbance spectra. The fingerprint region of the mid-IR was interpreted to postulate the effect of orientation and structure of key functional groups that made up part of the corrosion product. Efforts were made to assign bands in the region of < 600 cm{sup {minus}1}. Corrosion products based on a layer structure composed of metal hydroxides with metal chlorides or metal carbonates could be differentiated by observing hydroxide stretching and vibrational movements in the 3,000 cm{sup {minus}1} to 4,000 cm{sup {minus}1} and 800 cm{sup {minus}1} to 1,100 cm{sup {minus}1} regions, respectively. Corrosion layers that incorporated water coordinated or in a lattice could be identified. Effects of anions such as
DOI:10.5006/1.3290263      URL     [本文引用:]
[21] Bengtsson Blücher D, Lindström R, Svensson J E, et al.The effect of CO2 on the NaCl-induced atmospheric corrosion of aluminum[J]. J. Electrochem. Soc., 2001, 148: B127
A laboratory study of the effect of CO2 and NaCl on the atmospheric corrosion of aluminum is reported. The samples were exposed to pure air with 95% relative humidity and the concentration of CO2 was <1 and 350 ppm, respectively. Sodium chloride was added before exposure (0, 14, and 70
DOI:10.1149/1.1354614      URL     [本文引用:2]
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关键词(key words)
铝合金
阳极氧化膜
江津
工业污染大气
暴露实验

aluminum alloy
anodizing film
Jiangjin region
industrial polluted atmos...
exposure test

作者
周和荣
胡碧华
姚望
洪新培
宋述鹏

ZHOU Herong
HU Bihua
YAO Wang
HONG Xinpei
SONG Shupeng