模拟青铜文物在乙酸气氛中的腐蚀行为

采用电化学法制备了3种带锈青铜,以模拟青铜文物进行腐蚀试验。使用扫描电镜(SEM)、X射线衍射(XRD)和Raman光谱等方法分析了3种带锈青铜及裸青铜在乙酸气氛中腐蚀后的表面形貌和腐蚀产物。结果表明:在乙酸气氛中腐蚀后,裸青铜表面被腐蚀产物覆盖,且随腐蚀时间的延长,腐蚀产物增多,其腐蚀产物主要有Cu2O、碱式醋酸铜和醋酸铜;带Cu2O锈青铜表面的Cu2O立方晶体被破坏,转变成针状腐蚀产物,其腐蚀产物有碱式醋酸铜和醋酸铜;带CuCl锈青铜并未与乙酸发生反应,而是CuCl与空气中的水和氧气反应生成碱式氯化铜;混合锈具有三层结构,对青铜基体有一定的保护作用,其三层锈层的腐蚀是同时进行的,其腐蚀产物有碱式氯化铜、碱式醋酸铜和醋酸铜。     

带锈青铜文物材料在环境模拟介质中的腐蚀发展行为

目的研究3种带锈青铜及裸青铜文物材料在3种环境模拟液中的腐蚀发展行为。方法采用动电位扫描和SEM-EDS等方法研究试样的腐蚀特征和现象。结果在模拟大气环境介质中,电位在50~160 m V阳极极化范围内,与其他三种青铜材料相比,带CuCl锈青铜的阳极腐蚀电流密度最小;在模拟海水介质中,锈蚀青铜的腐蚀电流密度略大于裸青铜的;在模拟SO_2环境介质中,4种青铜试样的Rp值均大于大气环境介质中的。结论在模拟大气环境介质中,且阳极极化电位接近自腐蚀电位时,CuCl锈对青铜基体具有一定的保护性;在模拟海水环境介质中,带锈青铜的表面锈对基体没有保护作用;在模拟SO_2环境介质中,与在模拟大气环境介质中相比,SO_3~(2-)的引入会抑制青铜的腐蚀。表面形貌和能谱分析结果表明,裸青铜、CuCl锈青铜和混合锈青铜在模拟SO_2环境介质中,有点蚀现象发生,对粉状锈的生成有抑制作用。     

青铜文物表面腐蚀产物的组成及深度分布研究

青铜在模拟环境介质中的循环伏安实验及XRD测试结果表明,氧化过程主要为生成有害锈CuCl的过程,还原过程主要为CuCl还原成纯铜晶粒的过程,并且反应电流较大,对青铜基体的破坏性较大.运用高性能二次离子质谱(SIMS)观测到不同腐蚀电位下青铜表面腐蚀产物中均含有Cu、Sn、Cl、O、C、S元素,阴离子相对含量由大到小为Cl、O、C、S;腐蚀产物层由表及里Cu/Sn值始终小于合金中Cu/Sn,并且Cu离子含量基本不变,Sn离子含量有起伏,Cl、O离子含量有所下降.     

青铜器加速腐蚀的多孔氧电极研究

用具有适当空隙的电镀Cu-Sn-Pb三元合金作为青铜器模拟试片.应用腐蚀膏试验和微电极测试,研究了氯化亚铜(CuCl)、碱式氯化铜［Cu2Cl(OH)3］和碱式碳酸铜［Cu2(OH)2CO3］等腐蚀产物对氧的去极化反应的影响.以上述铜盐为活性物质制备出多孔氧电极,与青铜试片在3％NaCl溶液中组成腐蚀原电池,进行了阴极极化曲线测试,并进行以CuCl为活性物质的氧电极的恒电流放电和恒电阻放电测试.结果表明CuCl使试片的腐蚀速度高出其它二价铜盐两个数量级,对氧的去极化反应催化活性最高,氧电极的放电性能稳定并且模拟了被称为“粉状锈”主要成分的Cu2Cl(OH)3的生成过程 .提出了加速青铜器小孔腐蚀的多孔氧电极机理.     

NiCu低合金钢在含Cl~-的除氧NaHCO_3溶液中的腐蚀行为研究

对Ni Cu低合金钢在模拟深层地下水环境,即除氧0.1 mol/L Na HCO3+0.1 mol/L Na Cl溶液中,原位监测其在长时间浸泡条件下的开路电位变化曲线及阻抗谱的演化,研究电极表面的腐蚀演化规律,并与相同条件下低碳钢的腐蚀行为进行比较.结果表明,Ni Cu低合金钢在本实验溶液中的耐蚀性要显著优于低碳钢,尤其是其耐局部腐蚀的能力更优.合金元素Ni富集在内锈层中,可能以Ni Fe2O4的形式存在,而合金元素Cu的富集不明显,可能的存在形式为Cu Fe O2.     

黄铜冷凝管的点蚀

研究了 H68 A 黄铜在含 Cl~-溶液中的闭塞阳极行为。结果表明,黄铜的闭塞阳极不存在加速腐蚀的自催化效应,而是使闭塞区表面保持活性状态。其电位随阳极液 Cu~+浓度升高而变正。闭塞区Cu~+和 H~+不能向外扩散时,EE_(Cu/CuCl/Cl~-)进行生成 CuCl[s]的溶解反应。Cu~+和 H~+能向外扩散时,E>E_(Cu/Cu_2O/h 即能发生溶解。此时闭塞室内生成 Cu_2O。闭塞区外有扩散出来的 Cu~+经二次反应后生成的沉积物。黄铜冷凝管点蚀的腐蚀产物分布情况符合后者,这种点蚀在 E>E_(Cu/Cu_2O)时即能形成。黄铜管表面有碳膜时容易形成闭塞区并使电位升高,起到促进点蚀发生和加速点蚀作用,而不是产生点蚀的必要条件。为防止点蚀必须促使黄铜表面生成完整的保护膜。     

青铜器氯化物腐蚀产物的热分析

根除或有效控制有害的“粉状锈”是青铜器保护的关键技术。根据铜的氯化物在一定温度下易分解或挥发这一性质,本文利用热分析仪和X射线衍射（XRD）手段,对青铜试样表面生成的碱式氯化铜（Cu₂Cl(OH)₃）及氯化亚铜（CuCl）试剂粉末进行分析。结果表明,在大气环境中加热到350℃即可使氯铜矿分解,消除Cl^-;CuCl在420℃~430℃融化并挥发,在600℃挥发急剧加速,实验条件下至789℃已完全挥发。     

Cu2+及等离子电解氧化处理对Zr-4合金腐蚀性能的影响

采用电化学方法研究锆合金Zr-4在添加不同Cu2+浓度的0.5 mol/L NaCl溶液或0.5 mol/L Na2SO4中的腐蚀行为,探讨不同浓度Cu2+对Zr-4合金腐蚀性能的影响,同时,在10 g/L Na2SiO3.9H2O+10 g/L Na4P2O7.10H2O混合溶液中对Zr-4合金进行等离子电解氧化处理,并用极化曲线技术研究膜层的防护能力。结果表明:Cu2+能使Zr-4合金自腐蚀电位正移,降低极化曲线上钝化区的宽度,使得合金的抗孔蚀能力降低,腐蚀电流密度增加;在硫酸钠溶液中,Cu2+的添加没有使合金产生明显的孔蚀,这表明Zr-4合金的抗孔蚀能力下降是Cu2+和Cl共同作用的结果;等离子电解氧化处理能够大幅度提高Zr-4合金的抗孔蚀能力。     

土壤腐蚀过程中高锡青铜的形貌变化和元素迁移

采用在含模拟土壤介质(0.010 4 mol/L Na2SO4+0.028 2 mol/LNaCl+0.016 4 mol/L NaHCO3)的土壤中埋藏铸造青铜试样的方法研究高锡青铜的土壤腐蚀规律:采用金相显微镜观察腐蚀前后青铜的结构变化,扫描电镜(SEM)并结合能谱(EDS)对微区成分进行分析;用X射线荧光光谱(XRF)检测埋藏试样周围土壤中元素含量,同时用残留因子fCu/Sn和fCu/Pb定量分析腐蚀产物中Cu、Sn和Pb的残留情况.结果表明:在该环境下高锡青铜腐蚀首先从α相与δ相界面开始,且α相先于δ相发生腐蚀,留下未腐蚀的岛屿状δ相;高锡青铜腐蚀过程中Cu优先向周围土壤中迁移,最终形成的含O、C腐蚀产物中富含Sn和Pb.     

BTA和钼酸钠对青铜的协同缓蚀作用研究

采用动电位极化法、交流阻抗法研究了青铜试样在0.5 mol/L NaCl溶液中,苯并三唑（BTA）和Na2MoO4复合缓蚀剂对其电化学行为的影响,通过X射线光电子能谱技术分析了复合缓蚀剂在青铜表面形成的表面膜组成.结果表明,在0.5 mol/L NaCl溶液中,BTA和Na2MoO4复配使用具有良好的协同缓蚀效果,增强了对青铜阳极过程的抑制作用,提高了青铜电极表面膜电阻和电极反应的界面电荷转移电阻.XPS表面分析结果证明,在BTA和Na2MoO4复合缓蚀剂的作用下,青铜表面生成［Cu(Ⅰ)BTA］聚合物保护膜,SnO2,PbO,MoO3等金属氧化物沉积在表面膜上,改善了表面膜的致密性,使其具有良好的抗氯离子腐蚀性能.从而提高了表面膜的保护性能,有效地保护了青铜基体.     

Characterization of corroded bronze Ding from the Yin Ruins of China

This paper presents the result of scientific examinations carried out on the soil-buried archaeological bronzes Ding from Yin Ruins of China. Eight of typical fragments from different bronze Ding were selected as researched samples according to their deterioration characteristics. Optical microscopy (OM), scanning electron microscopy coupled with energy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to understand the corrosive morphological characteristics, to clear the nature of patina and to analyze the elementary composition of bronze Ding. The results indicated that it is not possible to distinguish the original lustrous metallic surface in most samples because of the corrosive crust. The substrate of bronze Ding contains74-86% Cu, 1.1-4.6% Pb, and 10-18% Sn, which is in agreement with the historical investigation in the ritual vessels of Shang time. Copper-containing compounds were the main constituents of natural patina: Cu₂(OH)₃Cl existed as corrosion product in all the powdery or crack surface; Cu₂(OH)₂CO₃ was the main corrosive product in a compact and hard corrosive surface. This study provides useful information for the restoration and protection of bronze Ding in Yin Ruins.     

Corrosion of bronze by acetic and formic acid vapours,sulphur dioxide and sodium chloride particles

This paper studies the corrosion of patinated and unpatinated bronze by acetic and formic acid vapours, sulphur dioxide and sodium chloride salt particles, at 100% relative humidity. Weight loss, X-ray diffraction, infrared and scanning electron microscopy were the techniques used. Acetic and formic acid vapours, sulphur dioxide and sodium chloride produce a high corrosion rate on bronze. In general, no protective effect was found by the patina on bronze. The principal compounds identified were Cu₂O, Cu₂S, Cu₅(SO₄)₂(OH)₆ · 5H₂O, Cu(CH₃CO₂)₂ · XH₂O and Cu(HCO₂)2.     

Corrosion of copper in seawater and its aerosols in a tropical island

A complete characterization of copper corrosion behavior has been carried out under permanent immersion, water line, splash zone and at the atmosphere (near and far from the sea) at the tropical Cuban archipelago. No significant differences have been determined for corrosion of copper under complete immersion for test sites representative of Cuban archipelago. The maximum corrosion rate was observed on the line of water, related to the partial removing of the corrosion products layer due to water movement (waves) and a higher availability of oxygen. Patina composition was characterized using XRD, IR, EDS and SEM techniques. Paratacamite (Cu₂(OH)₃Cl) was the main component of the patina formed under complete immersion, on the line of water and in the splash zone. In poorly polluted atmospheric marine environments also atacamite (another structural modification of Cu₂(OH)₃Cl) was found. When environmental SO₂ reaches a competitive level with the chloride aerosol the patina formed is a complex mixture of basic cupric chlorides (paratacamite and atacamite) and basic cupric sulfates, antlerite (Cu₃(SO₄)(OH)₄) and brochantite (Cu₄(SO₄)(OH)₆). Brochantite and basic cupric chlorides are detected at inland rural sites. The patina morphology reveals details about the local environment in which it is formed and shed light on its more or less protective role for the metal. The relatively large corrosion rate under complete immersion and on the line of water is related to the formation of a patina with poor adherence to the metal surface and to a porous layer of cuprite formed by relatively large octahedral crystals.     

Effects of alternating magnetic field on the corrosion rate and corrosion products of copper

The effects of alternating magnetic field on the corrosion morphologies, corrosion rate, and corrosion products of copper in 3.5% NaCl solution, sea water, and magnetized sea water were investigated using electrochemical test, scanning electron microscopy/energy dispersive analysis system of X-ray (SEM/EDAX), and X-ray diffraction (XRD). The results show that the corrosion rate of copper in magnetized sea water is minimal. Moreover, the surface of the specimen in magnetized sea water is uniform and compact as compared with those in 3.5% NaCl solution and sea water. The corrosion products of copper in magnetized sea water are mainly Cu2O and CuCl2. However, the corrosion products in sea water are CuCl, Cu2Cl(OH)3, and FeCl3·6H2O. The electrochemical corrosion mechanisms of copper in the three media were also discussed.     

Corrosion resistance of nanostructured magnesium hydroxide coating on magnesium alloy AZ31: influence of EDTA

A hexagonal nanosheet Mg(OH)_2 coating was prepared through a one-step hydrothermal method using LiOH solution as mineralizer and then modified by ethylenediaminetetraacetic acid(EDTA) to minimize the rapid corrosion of AZ31 Mg alloy.The performance of the coating was evaluated using electrochemical technique,hydrogen evolution measurements, nanoscratch test,Fourier-transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) patterns and field-emission scanning electron microscopy(FESEM).The results suggested that the corrosion rate of bare AZ31 Mg alloys was significantly reduced by one and two orders of magnitude through the protection from Mg(OH)_2 coating and modification with EDTA(i.e., EDTA-Mg(OH)_2 coating), respectively.FESEM micrographs indicated that the modification in EDTA elicits to the formation of an EDTA-Mg(OH)_2 composite with a thickness as twice as that of as-prepared Mg(OH)_2 coating.Nanoscratch tests revealed strong adhesion between the composite or Mg(OH)_2 coating and the substrate.The study of formation and corrosion mechanisms of the coatings manifested that Mg(OH)_2 was first formed near the intermetallic compound AlMn particles and gradually covered the entire surface, wherein the AlMn particles played an important role in the coating growth process.And it also proved that EDTA accelerated the formation of Mg(OH)_2.     

Sn-0.75Cu钎料接头在NaCl溶液中的电化学腐蚀行为(英文)

采用动电位极化及浸出方法研究Sn-0.75Cu钎料及Sn-0.75Cu/Cu接头在3.5%NaCl溶液中的电化学腐蚀行为。极化曲线测试结果表明Sn-0.75Cu钎料的腐蚀速率比Sn-0.75Cu/Cu接头的低。在特殊电位时的形貌观察及相分析表明,在Sn-0.75Cu钎料表面活化溶解区形成腐蚀产物Sn3O(OH)2Cl2。从活化/钝化区开始,Sn-0.75Cu钎料的表面完全被腐蚀产物Sn3O(OH)2Cl2覆盖,并且在极化测试后出现蚀坑。与Sn-0.75Cu钎料合金相比,Sn-0.75Cu/Cu接头的钎料表面在活化区形成较多的Sn3O(OH)2Cl2,在极化测试结束时腐蚀坑的尺寸较大。浸出实验结果证实了Sn-0.75Cu/Cu接头较快的电化学腐蚀速率引起较多的Sn从中接头中释放出来。     

Mechanistic studies of corrosion product flaking on copper and copper-based alloys in marine environments

The mechanism of corrosion product flaking on bare copper sheet and three copper-based alloys in chloride rich environments has been explored through field and laboratory exposures. The tendency for flaking is much more pronounced on Cu and Cu–4 wt%Sn than on Cu–15 wt%Zn and Cu–5 wt%Al–5 wt%Zn. This difference is explained by the initial formation of zinc and zinc–aluminum hydroxycarbonates on Cu15Zn and Cu5Al5Zn, which delays the formation of CuCl, a precursor of Cu₂(OH)₃Cl. As a result, the observed volume expansion during transformation of CuCl to Cu₂(OH)₃Cl, and concomitant corrosion product flaking, is less severe on Cu15Zn and Cu5Al5Zn than on Cu and Cu4Sn.     

A study of the corrosion products of aluminum brass formed in sodium sulfate solution in the presence of chlorides

The surface film forming on Al brass specimens immersed in stagnant Na₂SO₄ solutions containing chlorides at pH values 3.0–7.25 was examined by using chemical, electrochemical and X-ray techniques. In the absence of chlorides the surface film consists of oxides (CuO, Cu₂O) and cupric basic sulfates Cu₃(SO₄)₂.4H₂O, stable in the whole range of pH; the surface film is quite homogeneous and no dezincification or localized corrosion occurs. In the presence of chlorides, the surface film consists also of cuprous chloride (CuCl) and of cupric [Cu(OH,Cl)₂.2H₂O] and aluminum oxychlorides [Al₄₅O₄₅(OH)₄₅Cl] and aluminum oxides (Al(OH)₃]. The weight of the corrosion products is a maximum in solutions containing 5 × 10⁻³ M NaCl at each pH value. In the most acidic solutions the surface film is physically and chemically extremely unhomogeneous, thus favouring the occurrence of dezincification or localized corrosion phenomena.