2024铝合金表面无铬钛锆转化膜的制备与性能

采用钛酸盐和锆酸盐为主盐,开发了一种应用于2024铝合金表面的无铬钛锆转化膜。通过扫描电镜 (SEM)、能谱分析 (EDS)、中性盐雾实验、动电位极化曲线和电化学阻抗谱对转化膜的表面形貌、成分及耐蚀性能进行了表征和分析。结果表明：制备的无铬钛锆转化膜由微米级的微小颗粒组成,膜层均匀平整,无明显缺陷;无铬钛锆转化处理后的2024铝合金,经中性盐雾168 h,无明显腐蚀产物产生;钛锆转化膜具有较低的腐蚀电流和一定的钝化能力,可有效的提高铝合金的耐蚀性能。     

文摘辑要

正铝合金表面氧化锆转化膜的结构与性能采用氟锆酸工艺在AA6061铝合金表面制备出氧化锆转化膜,用扫描电镜和能谱仪分析了氧化锆转化膜的组织形貌和结构,采用电化学方法和中性盐雾实验研究了氧化锆转化膜的耐蚀性能.结果表明:制备出的氧化锆转化膜为无色膜,主要由Zr和Al的氧化物组成.氧化锆转化膜的耐腐蚀性能优异.涂覆环氧树脂漆或聚氨酯漆后的涂层体系可以通过1500h的中性盐雾实验,氧化锆转化膜可以用作铝合金的涂漆前预处理膜。     

2024铝合金化学转化膜与磷化底漆耐蚀性的研究

通过盐雾实验、稳态阳极极化曲线和电化学阻抗谱3种测试方法，对磷化底漆和阿洛丁(1200)化学转化膜进行了测试，结果发现磷化底漆的耐蚀性明显优于阿洛丁化学转化膜．在中性盐雾实验10个周期中，阿洛丁化学转化膜腐蚀明显，而磷化底漆完好如初．在稳态和弱极化区，两者抗蚀性能相似，而在强极化区，磷化底漆明显优于阿洛丁化学转化膜、在电化学阻抗谱上，磷化底漆极化电阻(Rp)比阿洛丁转化膜高1个数量级．     

2024铝合金表面无铬硅烷膜的制备与性能研究

采用硅烷A-187为前驱体,制备了一种应用于2024铝合金基体表面的无铬硅烷转化膜。通过扫描电子显微镜(SEM)、能谱(EDS)、表面分析系统(XPS)、中性盐雾实验、动电位极化曲线和电化学阻抗谱对硅烷膜的表面/截面形貌、成分及耐蚀性能进行了表征和分析。结果表明:制备的无铬硅烷水解液处理后的2024铝合金具有优异的耐蚀性能,中性盐雾实验168 h,无腐蚀产物产生,硅烷膜使铝合金的腐蚀电位正移154 m V;硅烷膜下基体腐蚀反应的阻抗值随浸泡时间逐渐升高,说明硅烷膜可以有效抑制基体的腐蚀,为2024铝合金提供良好防护。     

热镀锌层钛盐钝化膜耐蚀性能的研究

以钛盐为主盐,加入双氧水、硝酸(磷酸)、络合剂等配制无铬钝化液,经钝化后在镀锌层表面获得一层均匀的无铬钝化膜.通过电化学试验、盐雾腐蚀试验、大气暴露试验等测试手段对比研究了铬酸盐钝化膜、钛盐钝化膜、镀锌层的耐蚀性能以及影响钝化膜耐蚀性的因素.结果表明:镀锌层经钛盐钝化后耐蚀性能明显改善,在中性盐雾箱内可以通过48 h连续喷雾而不产生白锈.     

AZ31镁合金表面磷酸盐-高锰酸盐化学转化膜性能的试验研究

用磷酸盐-高锰酸盐在AZ31镁合金表面制备出无铬化学转化膜,并采用金相显微分析、扫描电镜分析、能谱分析、X-射线衍射分析、电化学方法、中性盐雾试验分别对化学转化膜封孔处理前后的表面形貌、成分、相结构和耐蚀性进行检测和评价.研究结果表明,无铬化学转化处理可以显著提高镁合金的耐蚀性,封孔后处理可以有效地封闭化学转化膜中存在的孔隙,并进一步提高镁合金的耐蚀性.     

AZ31B型镁合金表面钛盐化学转化膜

研究了一种镁合金表面无铬钝化的钛盐环保型化学转化膜处理工艺。利用中性盐雾试验和极化曲线法测试了转化膜的耐蚀性能,采用SEM、EDS等方法对膜的形貌、元素组成进行了研究。结果表明,钛盐转化处理后在镁合金表面形成含钛氧化物膜层,该膜层有良好的耐蚀性能。     

铝合金表面金黄色转化膜的研究

采用无毒高锰酸钾进行转化处理,在铝合金表面制备金黄色无铬转化膜.通过研究转化液组成和操作条件对转化处理效果的影响,确定了最佳处理工艺.经中性盐雾试验、扫描电镜(SEM)和能谱仪(EDS)分析测试了转化膜的耐蚀性、形貌和组成.研究结果表明,采用该工艺可获得耐蚀性能良好、颜色亮丽的金黄色转化膜.     

2A12铝合金表面有机复合涂层的耐蚀性能研究

以氟碳面漆、丙烯酸聚氨酯面漆、环氧玻璃鳞片胶泥中间漆、铝合金防腐底漆和底面合一铝合金专用防腐漆为原料,采用不同的配套方案在2A12铝合金表面制备了有机复合涂层,通过扫描电子显微镜(SEM)、中性盐雾实验、极化曲线测试和电化学阻抗谱(EIS)测试对有机复合涂层的耐蚀性能和耐蚀机理进行了研究。结果表明:有机复合涂层与2A12铝合金基体之间,以及有机复合涂层中各层之间均结合良好;中性盐雾腐蚀30 d后各有机复合涂层仍具有表面光泽,没有出现开裂和剥落;(底漆+中间漆+氟碳面漆)方案的有机复合涂层耐蚀性能最佳,使腐蚀电流密度下降了3个数量级,极化电阻上升了3个数量级,阻抗值提升约2个数量级。     

锈蚀输电铁塔防腐蚀底漆与涂装体系选择

对锈蚀输电铁塔进行磷化处理,以磷化膜作为底层,制备四种防腐蚀底漆试样,在此基础上,设计四种涂装体系并制备试样,按照国家相关标准对底漆试样和涂装体系试样进行机械性能和耐蚀性检测。结果表明,环氧铁红防锈底漆与磷化膜配套性能最好,附着力为0级,耐氯化钠浸泡时间可达720h,划格盐雾试验72h无变化,耐盐雾腐蚀试验1 000h无起泡、锈蚀、脱落等现象;环氧铁红防锈底漆、环氧云铁中间漆和氟碳面漆组成的涂装体系机械性能和耐蚀性能最佳,附着力为0级,耐碱与耐水时间均达480h,耐盐雾腐蚀试验3 000h无起泡锈蚀脱落等现象。     

The effect of temperature on corrosion behavior of AA5083 in brackish water and seawater

Al‐alloy, AA5083, as a lightweight structural material with favorable mechanical properties and, compared with other lightweight materials, good corrosion resistance has an increased usage in the marine environment. It is well known that all Al‐alloys, including AA5083, in the presence of chloride ions are more prone to corrosion. Determination of corrosion behavior of AA5083 in seawater and brackish water has been investigated and compared at 18, 25, and at 30°C. To obtain more accurate and realistic results, fresh seawater and brackish water were sampled as an electrolyte in Sibenik region. The investigation was carried out using the following electrochemical methods: open circuit potential measurement, electrochemical impedance spectroscopy, linear polarization resistance, potentiodynamic polarization, and cyclic polarization. After potentiodynamic polarization measurement, each alloy was examined using a metallographic microscope to clarify corrosion morphology. Obtained results have shown that an increase in temperature leads to an increase in corrosion activity of AA5083 in both electrolytes, while microscopic examination reveals that the dominant type of corrosion is pitting.     

Pitting and Stress Corrosion Cracking Susceptibility of Nanostructured Al-Mg Alloys in Natural and Artificial Environments

The stress corrosion cracking (SCC) behavior of two developmental nanocrystalline 5083 alloys with varied composition and processing conditions was studied. The results were compared to a commercial aluminum AA 5083 (H111) alloy. The pitting densities, size and depths, and residual tensile strengths were measured after alternate immersion in artificial seawater and atmospheric exposure under different loading conditions. Optical and scanning electron microscopy (SEM) with EDX was used to analyze the fracture surfaces of failed specimen after removal at selected intervals and tensile testing. One of the nanostructured Al-Mg alloys exhibited significantly superior pitting resistance when compared to conventional microstructured AA 5083. Under conditions where pitting corrosion showed up as local tunnels toward phase inclusions, transgranular cracking was observed, whereas under conditions when pitting corrosion evolved along grain boundaries, intergranular cracking inside the pit was observed. Pit initiation resistance of the nano alloys appears to be better than that of the conventional alloys. However, long-term pit propagation is a concern and warrants further study. The objective of this investigation was to obtain information regarding the role that ultra-fine microstructures play in their degradation in marine environments and to provide insight into the corrosion mechanisms and damage processes of these alloys.     

CORROSION BEHAVIOR OF A ZIRCONIUM-TITANIUM BASED PHOSPHONIC ACID CONVERSION COATING ON AA6061 ALUMINIUM ALLOY

The conversion coating was formed by dipping AA6061 in a fluorotitanate/zirconate acid and amino trimethylene phosphonic acid （ATMP） solution at room temperature. The formation process and the anti-corrosion performance of the conversion coating were investigated using electrochemical test and salt spray test （SST）, respectively. The electrochemical test shows that the Zr/Ti and ATMP coating improves the corrosion resistance of AA6061 as good as the chromate （VI） coating. But the results of SST show that the corrosion resistance of Zr/Ti and ATMP coating is not as good as the chromate （VI） coating. The corrosion area is less than 2% after 72 h.     

Use of the Devanathan-Stachurski cell to measure hydrogen permeation in aluminum alloys

The Devanathan-Stachurski (DS) cell has been successfully used to determine hydrogen permeation behavior in a wide variety of metals, but the DS cell has been much less successful with aluminum alloys. The DS literature is critically reviewed for aluminum alloys. An improved DS method is described and demonstrated for use with aluminum alloys (and probably Mg-based alloys). Experimental results are reported for the hydrogen diffusion coefficient, solubility, and trapping in the AA5083 aluminum alloy. The diffusion coefficient is reported for AA6061.     

铝合金表面电弧喷涂铝涂层工艺与性能

采用电弧喷涂工艺在6061铝合金基体表面喷涂高纯铝涂层,利用金相显微镜对涂层的组织进行观察,分析了基体与涂层的结合方式,测量了涂层的孔隙率.并采用质量分数为5%的NaCl溶液浸泡试验、盐雾试验和电化学试验,检验了涂层的耐腐蚀性.结果表明,利用电弧喷涂技术可以在6061铝合金基体表面形成均匀、致密、孔隙率低、结合良好的高纯铝涂层;高纯铝涂层耐腐蚀性较好,对铝合金基体起到了保护作用,涂层经过封孔工艺处理后保护作用更好.     

水热预处理对铝合金表面ZnAl-LDHs涂层防腐蚀性能的影响

目的提高表面ZnAl-LDHs涂层对铝合金的防腐蚀保护性能。方法首先将6061铝合金放入水热反应釜中,加入去离子水,在120℃温度下水热反应30 min。将经过水热预处理的铝合金分别放入50、80℃的0.005 mol/L的Zn(NO3)2溶液中浸泡4 h,在铝合金表面制备出ZnAl-LDHs涂层。利用XRD、SEM、EDS、EIS和极化曲线等技术,分析不同制备条件下,铝合金表面ZnAl-LDHs层的形貌、结构及其对铝合金的防腐蚀保护性能。结果水热预处理后,铝合金表面形成Al(OH)3和AlO(OH)混合层,在其上生长形成的ZnAl-LDHs涂层具有较优的层状结构、较高的结晶度和更加细小致密的纳米片。电化学阻抗和极化曲线的测试结果表明,表面ZnAl-LDHs层可以降低6061铝合金的腐蚀电流密度,提高腐蚀电位和电化学阻抗。水热预处理后的铝合金在80℃溶液中形成的ZnAl-LDHs层,其自腐蚀电流密度(J(corr))仅有0.018μA/cm^2,比未水热处理的铝合金上获得的ZnAl-LDHs层(0.101μA/cm^2)更低,在50℃溶液中形成的ZnAl-LDHs层也观察到相同的现象。结论通过水热预处理可在6061铝合金表面形成Al(OH)3和AlO(OH)混合层,将其作为ZnAl-LDHs层原位生长的前驱体,可以促进ZnAl-LDHs的结晶形核,提高其形核率,使ZnAl-LDHs层的纳米片更细小致密,从而使ZnAl-LDHs层对铝合金具有更好的防腐蚀保护性能。     

海洋工程用铝合金的腐蚀与防护研究进展

海洋工程用铝合金部件在服役环境下引发的点蚀、晶间腐蚀等已成为困扰机器装备使用寿命和稳定性的关键问题。目前,阴极保护、缓蚀剂、阳极氧化和保护涂层是针对海洋环境中铝合金腐蚀的常用防护措施。阐述了海洋工程装备常用的铝合金类型和使用场所,发现5系和6系铝合金是船舶制造和海洋平台搭建的首选材料,其中,具备优异力学性能、耐腐蚀性能的5系铝合金一般用来制作甲板、储存装置等大型主要承力构件。重点综述了铝合金在海洋大气区、浪花飞溅区、海水全浸区的腐蚀行为和腐蚀机制,经对比发现,与钢不同,铝合金在海水全浸区的腐蚀最严重,而在环境最恶劣的浪花飞溅区腐蚀损伤相对较轻;点蚀、晶间腐蚀是2种典型的铝合金腐蚀类型,同时应力腐蚀、微生物腐蚀也制约着铝合金在海洋工程领域的应用。最后分析了当前在海洋环境中对铝合金腐蚀防护采取的几种措施,指出工程实际中采用的防护方式为2种及2种以上措施的联合使用,并提出铝合金未来在失效行为分析、性能优化和涂层材料选择等方面的发展趋势,以期为研发在极端海洋环境下服役的铝合金及其防护材料提供参考。     

合金元素对铝合金在泰国曼谷地区初期腐蚀行为的影响

在泰国曼谷地区对5083、6063和7020 3种铝合金进行为期1 a的暴晒实验,采用SEM、电化学实验、XPS和扫描Kelvin探针显微镜(SKPFM)对3种铝合金初期腐蚀形貌及腐蚀机理进行研究。结果表明:6063铝合金中Mg、Si、Fe等合金元素含量较少,腐蚀电位相对较高,约为-0.66 V (vs SCE),腐蚀产物膜较为致密,耐蚀性较好,在泰国曼谷地区的腐蚀速率约为0.7 g/(m^2·a)。7020铝合金含有较多Mg、Zn等合金元素,腐蚀电位约为-0.78 V (vs SCE),腐蚀最为严重,腐蚀速率约为3.26 g/(m^2·a)。3种铝合金均含有Mn、Si、Fe等合金元素,从而形成Fe-Si-Al或Fe-Si(Mn)-Al第二相,第二相表面电位高于基体225~280 mV,在大气环境中第二相作为阴极相,周围的基体Al优先溶解脱落,成为点蚀坑。     

6061铝合金表面新型黄色微弧氧化陶瓷层的制备与表征

目的 研究6061铝合金表面新型微弧氧化黄色陶瓷层的制备工艺,并对其微观结构、成分、硬度、耐蚀性能等进行表征。方法 在以Na2SiO3为基础的电解液中加入Na2SnO3进行微弧氧化处理,制备出黄色微弧氧化陶瓷层,并与传统白色、黄色、黑色微弧氧化陶瓷层作对比。采用SEM和EDS分析膜层表面形貌和元素分布,借用XPS对膜层进行成分表征,使用硬度计测试其表面硬度,采用电化学工作站和人造海水腐蚀实验评价陶瓷层的抗腐蚀性能。结果 随着电解液中Na2SnO3浓度的增加,陶瓷层中Sn元素含量增加,Si元素含量减少,陶瓷层黄色饱和度不断增强。黄色含Sn陶瓷层制备过程中,电解液中的SnO32-在高温高压下转化为SnO2,导致陶瓷层硬度达到365HV,高于白色与黑色陶瓷层。在3.5% NaCl溶液中进行电化学测试,黄色含Sn陶瓷层的腐蚀电流密度与腐蚀电位分别为9.34×10-9 A/cm2和-0.34 V,耐蚀性优于白色和黄色含Mn陶瓷层。结论 在电解液中添加Na2SnO3可在铝合金表面生成具有较高硬度和耐蚀性能良好的类似沙漠黄色的陶瓷层,为铝及其合金在多领域的应用奠定了一定的实验基础。     

Influence of substrate composition on the formation of phytic acid conversion coatings

In this paper, the formation and corrosion resistance of the phytic acid conversion coatings on Mg, Al, and AZ91D magnesium alloy were contrastively investigated using scanning electronic microscopy (SEM), Auger electron spectroscopy (AES), Fourier transform infrared spectroscopy (FTIR), electronic probe microscopic analyzer (EPMA), electronic balance, and electrochemical methods. The influence of phytic acid conversion coating as a middle layer on the properties of the paint on magnesium alloys was also investigated. The results show that the formation process of the conversion coatings is evidently influenced by the compositions of the substrate. The coating on pure aluminum is thinner and compacter than that on pure magnesium and the coating formed on α phase in AZ91D magnesium alloy is thinner but denser than that on β phase. The phytic acid conversion coatings formed on Mg, Al, and AZ91D magnesium alloy can all increase their corrosion resistance. The active functional groups of hydroxyl and phosphate radical are rich in the conversion coatings, which can improve the bonding between the organic paint and magnesium alloy and then improve their corrosion resistance.