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针对2A12铝合金零件经硫酸阳极化后膜层存在黑斑或黑点现象,介绍了硫酸阳极氧化工艺流程、槽液成分、氧化参数及操作要点。通过分析影响2A12铝合金硫酸阳极氧化的主要因素,从零件预处理质量、工艺参数的选择、槽液日常维护和Cu^2+、Al^3+和Cl^-等杂质的处理及加工过程中零件的装挂等多方面提出改进、优化,使硫酸阳极化膜层出现黑点或黑斑的现象得以彻底消除。 相似文献
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对汽车用2024铝合金板材进行酒石酸阳极氧化处理,并研究了阳极氧化对铝合金的成分、结构、表面形貌及耐蚀性的影响。研究发现,铝合金阳极氧化膜是由表面多孔层和内部无孔层构成的。铝合金阳极氧化过程是一个氧化铝生成和溶解的动态过程。阳极氧化膜由刚玉结构的α-Al_2O_3和八面结构的γ-Al_2O_3构成,α相和γ相大大提高了阳极氧化膜的硬度和耐蚀性。阳极氧化膜为典型的多孔结构,孔洞分布均匀,孔径为50nm左右。 相似文献
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研究了稀土盐硫酸铈改性磷酸–硫酸阳极氧化处理对2A50铝合金表面耐腐蚀性能的影响。通过滴碱试验和铜加速乙酸盐雾(CASS)试验对改性前后阳极氧化膜的耐蚀性进行了研究,采用扫描电镜观察了不同阳极氧化膜的表面和截面形貌,测试了氧化膜的厚度,并对铈盐改性后的氧化膜进行了能谱分析,探讨了铈盐的作用机理。结果表明,稀土改性后得到的阳极氧化膜上孔分布均匀,孔隙率较高,其组成为Al2O3,氧化膜厚度由改性前的4.2μm提高到改性后的49.2μm,滴碱时间由35.9 s提高到186.9 s,CASS试验24、72和168 h的腐蚀评级分别由9、7和5级提高到10、9和8级。认为稀土盐的加入使氧化膜多孔层生长速率加快,阻挡层厚度增加,多孔部分结构更致密,从而提高了铝合金阳极氧化膜的耐蚀性能。 相似文献
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给出了铝合金化学除油及硫酸阳极氧化工艺条件.分析了影响铝合金硫酸阳极氧化膜层颜色的因素,如铝合金成分,机械加工方式,膜层均匀度和腐蚀等. 相似文献
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[目的]铝合金零件的疲劳性能是决定飞机服役寿命的关键因素。硫酸阳极氧化是铝合金零件常用的表面处理工艺,研究其对铝合金疲劳性能的影响对指导生产极其重要。[方法]针对新型航空铝合金7A65,采用重复退膜-阳极氧化的方式开展实验。通过疲劳试验机对试样进行疲劳性能测试,绘制应力-疲劳寿命曲线,分析和对比重复退膜和阳极氧化不同次数后7A65铝合金的疲劳性能。通过体视显微镜和扫描电子显微镜对典型断口形貌进行分析,并探讨了其疲劳失效机制。[结果]7A65铝合金在重复退膜-阳极氧化处理后疲劳极限明显下降。经过2次阳极氧化,7A65铝合金的疲劳极限下降为原疲劳极限的61.1%;继续进行退膜-阳极氧化处理,疲劳极限下降趋缓,4次阳极氧化后的疲劳极限为原疲劳极限的56.5%。在此过程中,其疲劳断口呈现出由单一裂纹源向多裂纹源,以及从韧性断裂向脆性断裂的转变。[结论]硫酸阳极氧化对7A65铝合金疲劳性能的影响较大,在生产中应当控制阳极氧化零件的返修次数。 相似文献
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由于现有的铝合金阳极氧化表面处理工艺采用的是弱酸电解液,且处理后没有对铝合金采取封闭措施,导致制备的阳极氧化膜抗腐蚀性能较差,铝合金局部腐蚀深度仍旧比较大,为此提出铝合金阳极氧化表面处理工艺研究。通过对铝合金高温退火、机械抛光、清洗去油、化学抛光以及出光除灰等预处理,去除铝合金表面的油污和自然氧化膜;将铝合金放置在制备的硫酸电解液中,接通2A/dm2恒定电流,以不锈钢作为阴极,对铝合金阳极氧化膜进行制备;通过对铝合金进行热水封闭处理,对铝合金阳极氧化膜表层的微孔进行填充和封闭。经实验证明,应用设计工艺后铝合金局部腐蚀深度小于传统工艺,能够起到良好的保护作用。 相似文献
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在Ce-Mn稀土钝化液中添加Cl-作为促进剂,以6063铝合金为基体制备了Ce-Mn转化膜。分别采用扫描电镜(SEM)和能谱仪(EDS)研究了转化膜的表面形貌及元素组成,并采用硫酸铜点滴腐蚀实验、动电位极化曲线以及电化学阻抗谱(EIS)研究了Ce-Mn转化膜的耐蚀性。结果表明,Ce-Mn转化膜主要由Ce、Mn、O等元素组成,往稀土钝化液中添加Cl-可使膜层更平整、致密,转化膜的平均耐点滴时间从50s提高至100s,在NaCl质量分数为3.5%的腐蚀介质中的腐蚀电流密度明显降低,转化膜极化电阻增大,铝合金的耐蚀性显著提高。 相似文献
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PENG Xiaoyan LI Lin HE Zhiyong LIU Kaiqi WANG Bingjun 《中国耐火材料》2007,16(1):25-29
In this paper,both oxidation and corrosion resistance of low-carbon magnesia-carbon materials containing 4.0wt% graphite with metallic Al and Mg-Al alloy powders as antioxidants were investigated.Meanwhile,the microstructures of samples corroded by slag were observed with optical microscope as well.The test results revealed the properties of oxidation and corrosion resistance of low-carbon magnesia-carbon materials could be improved obviously by adding metal Al powder and Mg-Al alloy powder.The rule of improving oxidation resistance was illegibility when metal Al powder and Mg-Al alloy powder were added together.It was harmful to corrosion resistance by mixed adding metal Al powder and Mg-Al alloy powder into the materials,at the same time,the corrosion resistance would decreased with the increasing of Mg-Al alloy content.The corrosion resistance of samples with 0.5wt% or 3.0wt% Mg-Al alloy was better. The oxidation resistance and corrosion resistance of materials with metal Al or Mg-Al alloy respectively were better than that with mixed metal Al and Mg-Al alloy. As a result, Mg-Al alloy was more suitable for low-carbon composite materials than metal Al as additives. 相似文献
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采用微弧氧化技术对2A12、3A21两种铝合金基材加工的零件进行处理,并在模拟海洋大气环境的条件下,依据GJB150.11A-2009《军用装备实验室环境试验方法》的要求对处理后的零件进行盐雾试验,研究铝合金微弧氧化膜层的腐蚀行为。结果表明,2A12铝合金经微弧氧化处理得到的黑色膜层光泽度低,具有良好的消光作用,微弧氧化膜层经酸性盐雾试验96 h后,出现不同程度的腐蚀脱落。 相似文献
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William A. Kern Michael J. McNallan Richard E. Tressler 《Journal of the American Ceramic Society》1996,79(7):1881-1891
Ceramic-matrix composites (CMCs) fabricated by the directed metal oxidation process (DimoxTM ) may have applications in heat exchangers in high-temperature corrosive environments such as those in the glass industry. The oxidation and corrosion properties of such CMCs with and without preformed metal-free surface layers have been investigated in the temperature range of 1000–1300°C. The untreated CMCs experienced rapid oxidation in air leading to mass increases of 100 to 140 mg/cm2 in less than 1 h. This occurred by oxidation of residual metal in the composite to form Al/Al2 O3 deposits on the surface. After the initial formation of the oxidation product, there is little further reaction during up to 300-h exposures to oxidizing atmospheres. Experimental composite coupons with metal-free surfaces were resistant to oxidation except for localized events associated with flaws. Small amounts of sodium silicate (2 to 40 mg/cm2 ) painted on the surfaces produced no corrosive effects on any of the specimens. Dynamic corrosion experiments, in which a continuous mist of sodium silicate was sprayed onto the surfaces, produced corrosion at 1300°C. 相似文献
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This study examined the effects of dissolved oxygen on the corrosion properties of aluminum cast alloy, A384, in bio-ethanol blended gasoline fuel at 100 °C. Oxygen enhanced the corrosion resistance of the alloy by forming a protective hydrous oxide film. The acetic acid and water produced by ethanol oxidation in the fuel had a corrosive and protective effect, respectively. However, the protective hydrous oxide film enhanced by the water suppressed the corrosiveness of the acetic acid in the fuel when the two by-products coexisted. Therefore, the water formed by dissolved oxygen in the bio-ethanol blended gasoline fuel enhanced the corrosion resistance of the aluminum alloy by promoting the formation of a protective surface film. 相似文献
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《Ceramics International》2023,49(18):30039-30048
The inherent micropores of micro-arc oxidation (MAO) coatings on magnesium alloy often cause poor long-term corrosion resistance. Herein, a low-porosity and high corrosion-resistant 8HQ/LDH/MAO composite coating, comprising a layered double hydroxide (LDH)-doped MAO primer and a top layer of 8-hydroxyquinoline (8HQ) inhibitor film, was deposited onto the magnesium alloy surface. Characterizations such as high-resolution field-emission transmission electron microscopy were performed to observe the synthesized nanoparticles’ morphology, size, composition, and structure. Results confirmed the successful synthesis of nitrate ion intercalated MgAl-LDH nanosheets and demonstrated the increase in thickness and denseness of the MAO coating after LDH doping. Based on electrochemical impedance spectroscopy and Tafel curves, the corrosion current density (jcorr) of the newly fabricated 8HQ/LDH/MAO composite coating was reduced by about three orders of magnitude. The low-frequency impedance modulus (|Z|ƒ=0.1 Hz) increased by nearly four orders of magnitude compared with that of bare Mg alloy. After 14 days of exposure to the corrosive electrolyte, the composite coating maintained a low jcorr, showing significantly enhanced corrosion resistance compared with single MAO coating. These findings demonstrated the synergism of LDH doping with 8HQ sealing to enhance the corrosion protection of MAO coating on magnesium alloy. 相似文献
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