共查询到20条相似文献,搜索用时 156 毫秒
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活化时间对镁合金化学镀镍层性能的影响 总被引:1,自引:0,他引:1
测试了活化时间对镁合金化学镀镍层的沉积速率、表面形貌、显微硬度及耐蚀性的影响。结果表明:当活化时间由1min增加到15min时,镀层的沉积速率变化不大;当活化时间为5min时,镀层表面的胞状物细小且分布均匀,微观缺陷数量较少,此时镀层的显微硬度最高、耐蚀性最好。 相似文献
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镁合金脉冲阳极氧化工艺 总被引:6,自引:0,他引:6
采用正交实验对镁合金在碱性环保型溶液的脉冲阳极氧化工艺进行了研究,分析了周期、占空比、电流密度、溶液温度、氧化时间等工艺参数对氧化膜层性能的影响,得出了最佳工艺为周期10 m s、占空比0.05、电流密度100 mA/cm2、温度40℃。采用扫描电镜、能谱、X射线衍射、电化学等多种测试方法对氧化膜层的性能、组分、形貌、结构以及耐腐蚀性能进行了研究。结果表明,该工艺能在镁合金表面形成灰白色的氧化膜层,膜层光滑致密,与基体结合牢固。氧化膜微观为均匀多孔结构,孔径也小于直流成膜,氧化膜主要由MgO和MgA l2O4组成,膜层耐腐蚀和结合力优于传统的直流工艺制备的膜层。 相似文献
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为提高ZK60镁合金的耐腐蚀性能,采用激光表面熔凝的方法在镁合金表面制备激光熔凝层,研究扫描速度对镁合金熔凝层形貌、微观组织、显微硬度及耐腐蚀性能的影响。采用光学显微镜、X射线衍射仪等仪器,观察分析熔凝层的表面及横截面形貌、粗糙度和显微组织,采用显微维氏硬度计测试分析熔凝层横截面的显微硬度,采用电化学工作站测试分析熔凝层的耐腐蚀性能。结果表明,激光表面熔凝处理在镁合金表面形成了厚度约为100~180μm的熔凝层,熔凝层厚度和表面粗糙度随扫描速度的降低而增加。熔凝层由细小等轴晶和放射状柱状晶组成,晶粒尺寸约1.5μm,熔凝层的相组成为α-Mg相和MgZn2相,显微硬度比基体提高了约33.7%。当扫描速度为25 mm/s时,镁合金熔凝层的自腐蚀电位比未处理镁合金向正向移动了0.118 V,自腐蚀电流密度比未处理镁合金降低了约2个数量级,耐腐蚀性达到最佳。 相似文献
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采用微弧氧化工艺对汽车用7075铝合金进行处理,生成氧化铝陶瓷膜。微弧氧化初期,随着微弧氧化时间的延长,致密层增厚,微弧氧化膜的硬度和耐蚀性显著提高;当微弧氧化时间大于100min时,由于致密层难以击穿,表面的疏松层导致微弧氧化膜的硬度增加缓慢,耐蚀性下降。微弧氧化时间为100min时制备的微弧氧化膜具有较高的硬度和最佳的耐蚀性。 相似文献
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Oxide films have been produced on AM60B magnesium alloy using plasma electrolytic oxidation process in an alkaline phosphate electrolyte with and without addition of titania sol. The microstructure and composition of the oxide films were analyzed by Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscope (XPS) and X-ray Diffraction (XRD). The corrosion resistances of the oxide films were evaluated using potentiodynamic polarization measurements in 3.5 wt% NaCl solution. It is found that the oxide film containing crystalline rutile and anatase TiO2 compounds are produced in an alkaline phosphate electrolyte with addition of titania sol. The oxide film formed in electrolyte with addition of titania sol has more uniform morphology with less structural imperfections than that formed in electrolyte without addition of titania sol. The results of potentiodynamic polarization analysis show that the oxide film formed in the present modified electrolyte is successful in providing superior corrosion resistance for magnesium alloy. 相似文献
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Corrosion behaviors of Zn/Al-Mn alloy composite coatings deposited on magnesium alloy AZ31B (Mg-Al-Zn) 总被引:1,自引:0,他引:1
After being pre-plated a zinc layer, an amorphous Al-Mn alloy coating was applied onto the surface of AZ31B magnesium alloy with a bath of molten salts. Then the corrosion performance of the coated magnesium alloy was examined in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the single Zn layer was active in the test solution with a high corrosion rate while the Al-Mn alloy coating could effectively protect AZ31B magnesium alloy from corrosion in the solution. The high corrosion resistance of Al-Mn alloy coating was ascribed to an intact and stable passive film formed on the coating. The performances of the passive film on Al-Mn alloy were further investigated by Mott-Schottky curve and X-ray photoelectron spectroscopy (XPS) analysis. It was confirmed that the passive film exhibited n-type semiconducting behavior in 3.5% NaCl solution with a carrier density two orders of magnitude less than that formed on pure aluminum electrode. The XPS analysis indicated that the passive film was mainly composed of AlO(OH) after immersion for long time and the content of Mn was negligible in the outer part of the passive film. Based on the EIS measurement, electronic structure and composition analysis of the passive film, a double-layer structure, with a compact inner oxide and a porous outer layer, of the film was proposed for understanding the corrosion process of passive film, with which the experimental observations might be satisfactorily interpreted. 相似文献
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Fakiha El-Taib Heakal Amany Mohammed Fekry Mohammed Ziad Fatayerji 《Journal of Applied Electrochemistry》2009,39(5):583-591
The influence of pH on the corrosion behavior of Mg-based AZ91D alloy was investigated in a constant composition phosphate
medium using various electrochemical techniques, complemented with surface analysis data. The studied solutions were 0.1 M
H3PO4, NaH2PO4, Na2HPO4 and Na3PO4 having pH values of 1.8, 4.5, 9.1 and 11.8, respectively. Spontaneous passivation was substantiated from monitoring the continuous
positive shift of the open circuit corrosion potential with both immersion time and solution pH. The impedance data indicated
more improvement in the insulating properties of the corrosion products formed on the alloy surface with increase in pH. The
electrolyte pH plays a determinant influence on surface film properties, as films formed in phosphate solutions with higher
pH values are thicker, thus affording better protection for the alloy than those formed in acidic solutions. Good agreement
was observed between the results obtained from electrochemical techniques and those from EDX and XRD examinations. The alloy
is more susceptible to corrosion in acidic phosphate solutions than in the alkaline ones. Crystalline magnesium (Mg), magnesium
hydride (MgH2) and magnesium oxide (MgO) were found to be the main constituents of the surface film after holding for 2 h in the acidic
phosphate medium. 相似文献
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