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为提高镁锂合金的耐蚀性,在镁锂合金表面制成了耐蚀性能较好的锰系磷化膜,采用极化曲线、电化学阻抗谱、时间电位曲线等电化学测试方法及SEM、EDS分析方法,研究了镁锂合金锰系磷化主盐浓度、磷化时间、金属离子、磷化助剂对磷化膜耐蚀性的影响,测试了试样在加入不同磷化助剂磷化时表面电极电位随时间的变化,观察了不同时间、温度条件下磷化膜的微观形貌,对比了锰系、锌系磷化膜的微观形貌,分析了膜层的组成.结果表明,随主盐高锰酸钾浓度的增加,膜层耐蚀性增加,适宜的磷化时间为20min,镍离子对磷化的促进作用大于铜离子,柠檬酸钠为较好的磷化助剂,锰系磷化膜较平整光滑,但膜层带有裂纹,随温度的增加裂纹加深,膜层的主要成分为磷酸锰. 相似文献
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《Materials Science & Technology》2013,29(5):446-453
A protective Ni–Co alloy coating was successfully prepared on sintered neodymium–iron–boron (NdFeB) magnet via potentiodynamic electrodeposition in this paper. The microstructure and surface morphology analysis of Ni–Co alloy coating showed that the surface morphologies were quite compact and more uniform than that prepared by direct current (DC) electrodeposition; significantly, the chemical composition analysis indicated that the content of Co in the alloy coatings amounted to 33–34?wt-%. Potentiodynamic polarisation and long term immersion test results revealed that the Ni–Co alloy coating could supply excellent corrosion protection for NdFeB substrate in 3.5?wt-% NaCl solution. Overall, the Ni–Co alloy coating with higher Co content prepared by potentiodynamic electrodeposition exhibited better corrosion protection for sintered NdFeB magnet compared with that prepared by DC electrodeposition. 相似文献
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通过调整工艺参数与氧气流量在LY12铝合金表面获得均匀、致密的微弧氧化膜层。利用SEM、XRD及电化学工作站等研究膜层的厚度、微观形貌、相组成以及耐腐蚀性能,讨论通氧微弧氧化作用机制,并分析氧气流量对膜层致密性的影响。结果表明:膜层厚度随电压、氧化时间和电解液组分浓度的增加呈规律性变化;氧气的助烧结作用能促进致密层的生长,随着氧气流量的增加,致密层厚度呈现先增加后减小的规律;KF 105g/L,KOH 85g/L,NaAlO_2 12g/L,电压110V,氧化时间15min,氧气流量为0.010L/s时得到厚度30μm的致密膜层,自腐蚀电位提高至-0.11V,腐蚀电流密度下降至2.1×10-6A/cm^2,比铝合金基体降低2个数量级以上,表现出良好的耐腐蚀性。 相似文献
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为了提高7A85铝合金的耐蚀性, 采用单极性正脉冲微弧氧化(MAO)技术在其表面制备了陶瓷膜层, 并采用稀土铈盐、铬酸盐和SiO2溶胶对MAO膜进行封闭处理。采用扫描电子显微镜(SEM)、X射线衍射仪和电化学工作站研究了封闭处理对膜层表面形貌、结构和在酸性NaCl溶液中腐蚀行为的影响。实验发现, MAO膜在酸性NaCl溶液中不能有效地保护铝合金基体。稀土铈盐和铬酸盐封闭处理通过沉积水合氢氧化物封闭孔隙, 可以提高MAO膜的耐蚀性。但在酸性溶液中, 封孔物质会和H+发生反应而溶解, 故经封闭的MAO试样也会发生腐蚀失效。SiO2溶胶封闭处理后MAO膜表面覆盖一层凝胶, 使膜层成为完整的致密层, 可以保护铝合金基体在酸性NaCl溶液中免受腐蚀。 相似文献
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W.F. Cui L. Jin L. Zhou 《Materials science & engineering. C, Materials for biological applications》2013,33(7):3775-3779
A porous bioactive titania coating on biomedical β titanium alloy was prepared by pre-anodization followed by micro arc oxidation technology. The effects of pre-anodization on the phase constituent, morphology and electrochemical corrosion behavior of the microarc oxidation coating were investigated. The results show that pre-anodization has less influence on the phase constituent and the surface morphology of the microarc oxidation coating, but improves the inner layer density of the microarc oxidation coating. The decrease of plasma discharge strength due to the presence of the pre-anodized oxide film contributes to the formation of the compact inner layer. The pre-anodized microarc oxidation coating effectively inhibits the penetration of the electrolyte in 0.9% NaCl solution and thus increases the corrosion resistance of the coated titanium alloy in physiological solution. 相似文献
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TiAl合金表面激光重熔等离子喷涂MCrAlY涂层研究 总被引:2,自引:0,他引:2
为了进一步提高TiAl合金表面等离子喷涂MCrAlY涂层的高温氧化性能,采用激光重熔工艺对涂层进行处理,研究了激光重熔对涂层微观组织及抗氧化性能的影响.用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了涂层氧化前后的表面形貌、微观组织和相组成.结果表明:经过激光重熔处理后,涂层片层状组织得以消失,致密性提高,消除了喷涂层的大部分孔洞、夹杂等缺陷,同时使Al元素在涂层表面的重新分布,形成了Al的富集区;等离子喷涂MCrAlY层能显著提高TiAl合金的抗高温氧化性能,经过激光重熔后可进一步提高其抗高温氧化性能. 相似文献
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Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合镀层的性质和组成研究 总被引:2,自引:0,他引:2
为了获得耐蚀性能优异的复合化学镀层,利用中性化学复合镀技术,在A3碳钢片表面制备了金黄色光亮致密的Cu-Sn-P-ZnCr2S4和Cu-Sn-P-CdCr2S4纳米复合化学镀层.用扫描电子显微镜(SEM)观察了镀层外貌;以称重法测定厚度;通过5%NaCl溶液、1%H2S气体加速腐蚀试验、抗粘性试验及室温氧化试验等多种手段测定了其性能;用X射线光电子谱(XPS)及俄歇电子能谱(AES)测定了其价态及组成.结果表明:Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合材料镀层的性能优于Cu-Sn-P合金镀层,复合镀层Cu-Sn-P-ZnCr2S4中,各原子百分数(%)约为: Cu 68.00,Sn 3.50,P 6.90,Zn 2.10,Cr 4.20, S 8.40,C 6.80;Cu-Sn-P-CdCr2S4中:Cu 69.00,Sn 3.30,P 5.90,Cd 2.4,Cr 4.8, S 9.60,C 4.80.Cu-Sn-P-ZnCr2S4占镀层的93.10%,Cu-Sn-P-CdCr2S4占镀层的95.00%.所得镀层耐蚀性好,耐盐水及室温氧化性能均优于Q235钢片和相近厚度的Cu-Sn-P合金镀层. 相似文献
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This research demonstrates a novel one-step electrochemical method to fabricate thick bilayer coatings on magnesium alloy in acid phosphate electrolyte containing aniline monomer and styrene-acrylic emulsion (SAE) with pulsed DC voltage, The morphologies, XRD and FTIR results show that the bilayer coating consists of an inner oxide layer and an outer polyaniline (PANI)/SAE composite layer, It is believed that the bilayered structure achieved results from a hybrid process combining electropoly-merization (EPM) of aniiine, electrophoretic deposition (EPD) of SAE and plasma electrolyte oxidation (PEO) of magnesium alloy substrate. Electrochemical corrosion tests indicate that the bilayer coating can provide superior corrosion protection to the magnesium alloy substrate in 3.5 wt.% NaCl solution. 相似文献
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镁合金微弧电泳复合膜层的微观结构和抗腐蚀性能 总被引:2,自引:0,他引:2
采用恒压模式在硅酸盐系电解液中制备镁合金微弧氧化陶瓷层,对比研究了微弧电泳和直接电泳镁合金的截面形貌、结合力大小以及抗腐性能差异.结果表明:在镁合金微弧氧化陶瓷层的表面可制备电泳有机层,简化了电泳工艺;在微弧电泳复合膜层间形成机械咬合力和化学键力,附着力等级可达1级;经800 h中性盐雾腐蚀试验后,复合膜层腐蚀增重量和样品表面的形貌均没有明显的变化;与微弧氧化陶瓷层和直接电泳有机层相比,微弧电泳复合膜层的电化学稳定性显著增强,腐蚀电流相分别减少了约5个和2个数量级. 相似文献
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运用电沉积法制备Ni-P-W-WC复合镀层,着重研究了制备工艺和镀层性能.以镀层中碳化钨含量、镀速和镀层外观为指标,探讨了电流密度、电沉积时间、镀液中WC含量、镀液中钨酸钠含量、镀液pH等因素影响规律,确定了复合镀层的最佳工艺条件为:以Ni为阳极、电沉积时间为40 min、镀液中WC含量为14 g/L、镀液中钨酸钠含量为120 g/L、镀液pH为4.0、电流密度是4A/dm2.并用扫描电镜、X-衍射分析仪、阳极极化曲线等手段表征了复合镀层的形貌、结构、耐蚀性、抗氧化性等性能,结果表明,与Ni-P-W复合镀层相比,Ni-P-W-WC复合镀层有良好的综合性能. 相似文献
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Effect of Thermal Oxidation on Microstructure and Corrosion Behavior of the PVD Hf‐Coated Mg Alloy 下载免费PDF全文
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为了提高ZK61S镁合金的耐腐蚀性能,采用微弧氧化方法以不同电压(300,380,450 V)在ZK61S镁合金表面制备氧化膜并进行封孔处理。利用金相显微镜、扫描电镜、X射线衍射仪分析膜层的形貌、结构和组成;通过腐蚀电位试验、中性盐雾腐蚀试验及抗剥落腐蚀试验进行耐腐蚀性能考核。结果表明:微弧氧化呈现疏松多孔形态且均匀覆盖于基材表面,主要由Mg、MgO和Al_2Si_2O_5(OH)4相组成;微弧氧化处理后试样的腐蚀电位显著提升,且380 V所得微弧氧化试板的腐蚀电位达到-881.53 m V,经过408 h的中性盐雾腐蚀试验后的腐蚀速率为0.012g/(m~2·h),耐蚀性能比未进行表面处理的基材提高了88倍;经封孔处理的微弧氧化试板经过456 h的中性盐雾腐蚀试验后腐蚀速率降低到0.003 g/(m~2·h);封孔处理使微弧氧化膜的抗剥落腐蚀性能由微弧氧化后的EB级提升到EA级。 相似文献
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In this study, multilayered AlN (AlN + AlN + AlN) and AlN + TiN were coated on AZ91 magnesium alloy using physical vapour deposition (PVD) technique of DC magnetron sputtering, and the influence of the coatings on the corrosion behaviour of the AZ91 alloy was examined. A PVD system for coating processes, a potentiostat for electrochemical corrosion tests, X-ray difractometer for compositional analysis of the coatings, and scanning electron microscopy for surface examinations were used. It was determined that PVD coatings deposited on AZ91 magnesium alloy increased the corrosion resistance of the alloy, and AlN + AlN + AlN coating increased the corrosion resistance much more than AlN + TiN coating. However, it was observed that, in the coating layers, small structural defects e.g., pores, pinholes, cracks that could arise from the coating process or substrate and get the ability of protection from corrosion worsened were present. 相似文献