Corrosion behavior of LY11 aluminum alloy in soil

1lNTRODUCTIONAluminumanditsalloys,justlessthansteels,werewidelyusedincommunicati0nca-ble,pipelineandpowerstationandsooninsoil.Soilcorrosionexperimentsofvariousmaterialshavebeenconductedabroadsince1920,[1~3].Inourcountry,thenetworkofsoilcorrosionhavebeenbuiltsince195Os,steelandleadspecimenshavebeenburiedfr0mthen..[4'5],whilestain-lesssteelsandnonferrousmetalssince1989[6].Inthisexperiment,thecorrosionbehavi0rofLY1laluminumalloywasstudiedinneutralsoilofShenyang,Chengdu,acidsoilofShenzhen,Y…     

Corrosion behavior of CuCrNiAl alloy in HCl solutions

1 Introduction Cu alloy has become a kind of important materials for ocean construction as its excellent anti-corrosion performance. Though this kind of alloy has been applied for a long time, it often undertakes serious corrosion, low strength and leakag…     

Corrosion behavior of Cu-Ni-Ag-Al alloy anodes in aluminium electrolysis

The behavior of Cu-Ni-Ag-Al alloy used as anode for aluminum electrolysis was directly visualized in a two-compartment see-through cell during electrolysis, and its performances were tested at 850℃ in acidic electrolyte molten salts consisting of 39.3%NaF-43.7%AlF3-8%NaCl-5?F2-4%Al2O3 for 40 h in a laboratory cell. The results show that nascent oxygen oxidizes the anodic surface to form oxide film at the beginning of electrolysis. X-ray diffraction analysis of alloy surface show that the oxide film on the anodic surface consists of CuO, NiO, Al2O3,CuAl2O4 and NiAl2O4. However, SEM image shows the oxide film is porous, loose and easy to fall into electrolyte and to contaminate aluminum. The corrosion mechanism of metal anodes was analyzed.     

Corrosion behavior of WE54 magnesium alloy in 3.5%NaCl solution

The corrosion behavior of WE54 magnesium alloy was investigated in 3.5%NaCl aqueous solution. The electrochemical study shows that the value of corrosion potential of WE54 magnesium was -1.8V（vs SCE）. In the initial stage of immersion, a kind of visible thin film, which has the appearance of artificial conversion coating by microscopy observation, formed on the surface of WE54 alloy. Through the comparison of corrosion behavior between WE54 and AZ91D, it is shown that the value of corrosion potential of WE54 is approximately 200 mV lower than that of AZ91D, and the corrosion rate of WE54 was one order smaller than that of AZ91D. After 72 h constant immersion and corrosion products removal, deeper grooves along grain boundaries was revealed but lighter corrosion was apparent on the matrix of WE54 alloy. As far as AZ91D alloy was concerned, severe localized corrosion was dominant and network-bone-like structure was remained.     

氧化时间对2A12铝合金阳极氧化膜开裂行为的影响

采用不同阳极氧化时间制备氧化膜,并采用扫描电镜、电子探针、连续性检测、交流阻抗法和盐雾腐蚀试验对阳极氧化膜进行了研究。结果表明,不同阳极氧化时间生成的氧化膜层经热冲击后都会出现非穿透性裂纹;随阳极氧化时间延长,经热冲击后,氧化膜层裂纹密度增大。综合考虑不同氧化时间下制备的氧化膜的开裂行为和耐蚀性变化,阳极氧化30 min制备的膜层在热冲击后具相对较好的防护性能。     

Corrosion behavior and microstructural characteristics, of the Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy with different manufacturing processes

The best manufacturing process for a high Nb-containing Zr-based alloy was determined by means of a corrosion test under a 400 °C steam condition, and a microstructural analysis was performed on the Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy, which was made with different manufacturing processes. This alloy was manufactured as sheets through the application of various manufacturing processes; the processes were controlled by a combination of the intermediate annealing temperatures and cold working steps after a water quenching of the β region. The corrosion behaviors of the Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy were clearly affected by the manufacturing conditions, and the corrosion resistance was considerably increased by the application of sequences of cold rolling and annealing. Microstructural analysis of the alloy sheets confirms that the corrosion resistance of the Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy can be estimated by a concentration of Nb in the precipitates, regardless of the manufacturing processes. Moreover, the pole figure evaluation of the oxide layers that formed on the Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy sheets with different manufacturing processes verifies that the (111) and (200) textures of the monoclinic ZrO₂ phase are well developed when the corrosion resistance is increased.     

热镀锌层在模拟沿海工业大气环境中的腐蚀行为

通过无浸润式干湿交替循环加速腐蚀试验模拟热镀锌层在沿海工业大气环境中的腐蚀过程. 采用腐蚀失重和动态极化曲线,结合扫描电子显微镜(SEM)、能谱分析仪(EDS)、X射线衍射(XRD)和极化曲线分别对腐蚀24,48,96,192,336和672 h的热浸镀锌钢试样进行测试分析. 结果表明,镀锌层的腐蚀动力学变化规律符合经验公式D=Btn,腐蚀速率随时间延长先减小后增大. 腐蚀产物在96 h前均匀致密,腐蚀过程受阴极扩散过程控制,96 h后腐蚀过程受阳极过程控制. 含Cl元素的腐蚀产物NaZn4SO4Cl(OH)6·6H2O和Zn12(OH)15Cl3(SO4)3·5H2O对镀锌层的保护作用比初期产物Zn5(CO3)2(OH)6等保护作用差.     

A comparative study on the corrosion behavior of NdFeB magnets in different electrolyte solutions

Sintered NdFeB magnets possess excellent magnetic properties. However, the corrosion resistance property of NdFeB is very poor due to its multiphase microstructure consisting of matrix phase Nd₂Fe₁₄B, Nd‐rich phase, and B‐rich phase. The corrosion behavior of NdFeB magnets in sodium hydroxide (NaOH), sodium chloride (NaCl), nitric acid (HNO₃), and oxalic acid (H₂C₂O₄) solutions was investigated by immersion and electrochemical tests. HNO₃is the strongest corrosive electrolyte compared with the other three solutions. The increase in HNO₃concentration can accelerate the corrosion of NdFeB magnets. NaCl belongs to medium corrosion electrolyte. A NaCl concentration of 0.5 M shows the severest corrosive feature in comparison with other concentrations of NaCl solution. NdFeB hardly suffers corrosion in NaOH and H₂C₂O₄solutions owing to the formation of passivation films on the surface of magnets. Based on the corrosion behavior of NdFeB in different electrolytes, the possible corrosion mechanisms are discussed.     

钛合金阳极氧化膜在Hank''''s溶液中的腐蚀行为

利用扫描电镜(SEM)和恒电位阶跃法，研究了不同工艺条件下得到的钛合金(TC4)阳极氧化膜在Hank’s模拟体液中的耐蚀性。分析了不同电解液组成、电解液温度及阳极氧化时间对其耐蚀性的影响。结果表明在磷酸溶液中生成的氧化膜耐蚀性较好，此外电解液的温度、极化时间对膜层耐蚀性也有显著影响。     

Corrosion behavior of an Al-6Mg-Sc-Zr alloy

The corrosion behavior of an Al-6Mg-Sc-Zr alloy was studied and compared with that of an Al-6Mg-Zr alloy. The addition of scandium into the Al-6Mg-Zr alloy reduced the susceptibility to exfoliation corrosion. By using the constant load tensile method in a 3.5 wt.% NaCl solution, the resistance to SCC of the Al-6Mg-Sc-Zr alloy was higher than that of the Al-6Mg-Zr alloy. When the specimens were not applied with an anodic current, the Al-6Mg-Sc-Zr alloy was resistance to SCC and no brittle cracking was found on the fracture surface. When an anodic current was applied, the Al-6Mg-Sc-Zr alloy specimens failed as a result of accelerated corrosion rather than SCC. It was believed that the addition of scandium re- sulted in （Al3Sc, Zr） particles that greatly refined grains and promoted the formation of homogeneous discontinuous distribution of β-phase in the alloy base, which much contributed to good corrosion resistance of the Al-6Mg-Sc-Zr alloy.     

AZ91D镁合金微弧氧化膜在不同浓度NaCl溶液中的腐蚀行为(英文)

采用微弧氧化技术(MAO)在镁合金 AZ91D 表面制备微弧氧化陶瓷膜。利用电化学技术和浸泡实验研究该镁合金试样在不同浓度(0.1%,0.5%,1.0%,3.5%和 5.0%,质量分数) NaCl 溶液中的腐蚀行为。结果表明,试样的腐蚀速率随着氯离子浓度的升高而增大。在较高浓度(1.0%,3.5%和 5.0%)的 NaCl 溶液中的主要腐蚀形式是点蚀,而在较低浓度(0.1%和 0.5%)中是全面腐蚀。腐蚀过程可以分为两个阶段:亚稳态蚀点的出现和蚀点的生长。根据腐蚀过程中阻抗谱的特点,对镁合金微弧氧化膜试样在不同浓度 NaCl 溶液中浸泡 120 h 提出了不同的等效电路来模拟其腐蚀行为。     

高pH值完井液中钛合金管材的腐蚀行为研究

基于高温高压腐蚀速率和原位电化学测试,并结合分子动力学模拟和第一性原理计算,探讨了钛合金(TC4)管材在高pH值完井液中的腐蚀行为,以及钝化膜的热力学稳定性。结果表明:TC4钛合金在180℃的高pH值磷酸盐完井液中的腐蚀极为严重,其均匀腐蚀速率高达0.4429mm/a;在高pH值磷酸盐完井液中,TC4钛合金的腐蚀为阳极反应过程控制,随着温度的升高,其腐蚀电位、腐蚀产物膜的膜阻和极化电阻显著降低,腐蚀反应的热力学驱动力增大、动力学阻力降低,腐蚀电流密度显著升高;在碱性溶液中,TiO_2钝化膜的钛氧键发生不同程度断裂,并且随着温度升高、碱性增强,TiO_2与溶液的界面结合能逐渐增大,钝化膜的热力学稳定性明显降低;在碱性焦磷酸钾溶液中,TiO_2钝化膜均可与K_2HPO_4、K_3PO_4反应生成疏松多孔的KTiOPO_4腐蚀产物膜,但TiO_2与K_3PO_4反应的热力学倾向更大。     

6063铝合金阳极氧化膜腐蚀行为研究

分别对6063铝合金原样与硫酸直流阳极氧化法处理样品样进行铜加速盐雾腐蚀,考查时间对腐蚀样品形貌、元素分布及电化学腐蚀行为的影响,利用质量损失法对腐蚀动力学进行分析.结果表明:腐蚀时间延长,腐蚀电流增大,原样表面腐蚀产物明显增多;阳极氧化处理后改善6063铝合金的抗腐蚀性,阳极氧化样的抗腐蚀性能在盐雾条件下提高2.2倍,在暴露环境下可提高4.5倍.     

Mg-Li合金的腐蚀机理与表面防护

Mg-Li合金作为目前最轻的金属结构材料,在航空航天、军事、电子产业等领域具有良好的发展前景.但较差的耐蚀性严重制约了Mg-Li合金的广泛应用,因此研究其腐蚀机理和表面防护极为重要.基于国内外的研究进展,综述了Mg-Li合金的腐蚀机理,系统总结了Mg-Li合金的表面防护方法,包括电镀、化学镀、化学转化、阳极氧化、涂层涂...     

高铝青铜Cu-14Al-X合金在3.5%NaCl溶液中的腐蚀行为

通过静态浸泡腐蚀实验、电化学实验、X射线衍射分析、扫描电镜、电子能谱仪、电子探针等方法研究高铝青铜合金Cu-14Al-X在3.5%NaCl(质量分数)溶液中的耐蚀性能及腐蚀行为。结果表明:在NaCl溶液中,Cu-14Al-X合金具有良好的耐蚀性能,合金中的(α 2γ)共析体和β′相、α相、K相相比,具有优先腐蚀倾向,合金发生的主要是脱铝腐蚀。腐蚀钝化膜的形成及热处理后合金各相成分趋于一致,均使合金耐腐蚀性能得到改善。     

不同晶粒尺寸的Cu-40Ni合金在酸性介质中的耐蚀性能

采用电弧熔炼(CA)和机械合金化(MA)通过热压烧结工艺制备了晶粒尺寸差别较大的Cu-40Ni合金,借助于PARM273A和M5210电化学综合测量仪,利用动电位扫描法和交流阻抗技术对比研究了上述合金在酸性介质中的腐蚀电化学性能以及腐蚀机理。结果表明:随着H 浓度的增加,CA Cu-40Ni合金的自腐蚀电位负移,而MA Cu-40Ni合金则正移,两种合金的动电位扫描极化曲线均未出现钝化现象;随着H 浓度的增加,CA Cu-40Ni合金的极化电阻增大,腐蚀电流减小,合金的耐蚀性能增加,而MA Cu-40Ni合金的极化电阻减小,腐蚀电流增加,合金的耐蚀性能降低。两种合金的交流阻抗谱均由双容抗弧组成,腐蚀过程受电化学反应控制。晶粒细化后,合金中存在大量晶界,参与腐蚀反应的活性原子数增加,促使MA Cu-40Ni合金的腐蚀速度高于CA Cu-40Ni合金。     

Corrosion behavior of a CuCrNiAl alloy in the presence of NaCl deposit

The corrosion behavior of a CuCrNiAl alloy with NaCl deposit at 700 and 900℃ was studied by means of metalloscope, XRD, SEM/EDX, and thermogravimetric analysis. The results indicated that the corrosion of the CuCrNiAl alloy beneath the NaCl deposit is severe; the corrosion production is loose and easy to scale off; the Cr phase is easier to erode than the Cu phase, and the contents of Cu and Cr decrease when the content of Ni increases in the matrix of the alloy beneath the corrosion region. The effects of distortion on the corrosion of the CuCrNiAl alloy were discussed, and the acceleration mechanisms of NaCl on the corrosion were also discussed.