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Preparation and Corrosion Resistance of Rare Earth Ceramic Film on AZ91 Magnesium Alloy 总被引:1,自引:0,他引:1
With the purpose of improving corrosion resistance and solving environmental pollution caused by traditional protective technique, rare earth ceramic film on AZ91 magnesium alloy was prepared by dip coating process, and technical parameters of preparation were defmed. Microstructure and composition of the film were studied and corrosion resistance was evaluated as well. The results show that rare earth ceramic film is uniform,dense, with strong cohesion and intact coverage. The film is mainly made up of CeO2 and MgCeO3. The results of corrosion experiments approve that the film acts as a barrier to isolate the contact of the substrate with corrosion media and decreas corrosion rate. Polarization curve of the coated sample shiftes to positive potential obvito 2.7 × 104 Ω. These facts indicate that rare earth ceramic film could effectively improve corrosion resistance of AZ91 magnesium alloy. 相似文献
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Preparation and Performance of Rare Earths Chemical Conversion Film on Magnesium Alloy 总被引:2,自引:1,他引:2
Lü Qiaoyan 《中国稀土学报(英文版)》2006,24(Z2)
Golden yellow cerium conversion film was obtained on magnesium alloys surface by immersion method and the preparation parameters were established. The influence of different process parameters on the surface morphology and performance of the conversion film were analyzed by means of SEM and electrochemical method. Formation dynamics about cerium conversion film on magnesium alloy in solution containing cerium salt and the anti-corrosion behavior of the conversion film in 3.5% NaCl solution were studied by electrochemical method respectively. The results shows that the conversion film is more compact at room temperature when concentration of cerium sulfate is 10 g·L-1 in the solution; the open circuit potential of the magnesium sample moves up to positive direction about 100 mV, the surface of conversion film becomes even and lustrous, and the adhesion intensity of conversion film increases when adding aluminum nitrate into the solution containing cerium salt. The pH value of the solution and immersion time of the sample in the solution also affect the surface morphology and anti-corrosion property of the conversion film. After covered by rare earths conversion film, the anti-corrosion property of magnesium alloy is obviously improved. Rare earth conversion film has self-repairing capability in corrosion medium. 相似文献
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The surface of carbon fiber reinforced Mg matrix (Cf/Mg) composites was modified by treatment of rare earth conversion coating, and nontoxic, non-pollution Ce conversion coatings were prepared. The effect of the coatings on corrosion behaviors of composites was investigated by electrochemical polarization technology and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The higher Ecorr and lower icorr were obtained by Ce conversion coatings. EIS results showed that the higher values of R2 were obtained by treatment containing CeCl3, the high corrosion resistance occured in treatment containing CeCl3, the low corrosion resistance in uncoating sample, the coating of treatment containing Ce(NO3)3 was medium. The microstructure of Ce conversion coatings was observed by scanning electron microscopy (SEM), and the elements of corresponding for coatings was characterized by energy dispersive spectrometer (EDS). The micro-cracks and Ce-riched spherical particles were characteristics of these coatings. 相似文献
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Liu Shengfa Liu Linyan Huang Shangyu Xu Ping Wang Zhongfan 《中国稀土学报(英文版)》2006,24(2):247-247
Effect of cerium addition on corrosion resistance of AZ91 magnesium alloy was investigated using the static weight loss and polarization curve method as well as metallographical observation. The results indicate that a small amount of cerium (0.2% - 0.8%) in AZ91 magnesium alloy can significantly reduce the corrosion rate, enhance the electrode voltage and lower corrosion current density in 3.5%NaCl aqueous solution, and AZ91-0.8% Ce alloy has better corrosion resistant performance. The reason for increasing corrosion resistance is attributed to the addition of Ce, refining the α-Mg grain, reducing the segregation of element Al, and improving the morphologies of β-Mg17 Al12 phases. 相似文献
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Magnesium alloys are widely used as shells of 3C (computer, mobile phone and consumer electronics) equipments for its impressive mechanical and physical properties, such as low density, good resistance to electromagnetic radiation, suitable for high pressure diecasting and easily recycling, etc. But poor corrosion resistance confines its extensively application. In this paper, protective coatings was successfully prepared on AZ91D magnesium alloys by micro-arc oxidation (MAO) and painting process. Microstructures and phases of MAO coatings were invesgated with scanning electron microscope (SEM) and X-Ray diffractometer. Mechanical properties of MAO coating, such as adhesive force and corrosion resistance, were also tested. Results showed that MAO coatings were a good base for painting process. MAO coatings with paint have good adhesive properties to base metal and excellent corrosion resistance. Micro-arc oxidation with painting process is a good kind of surface treatment to improve the corrosion resistance of mobile phone shell made of AZ91D magnesium alloys. 相似文献
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The effect of Ce on ignition point of AZ91D magnesium alloy chips was studied. For the AZ91D and the AZ91D-xCe magnesium alloys, changing the sizes of the chips in the range of 58 - 270 μm has a limited influence on ignition point, however, the shift of the content of Ce has much effect on ignition point. Increasing the Ce content, x from 0.15 to 0.25, the ignition point increases with increasing of Ce; however, x from 0.25 to 0.45, the ignition point decreases with increasing of Ce. By the addition of Ce of 0.25 %. the ignition point is raised by 43℃. 相似文献
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稀土铁基自熔基合金抗硫化氢腐蚀性能的实验研究 总被引:1,自引:0,他引:1
近年来关于稀土在热喷涂(焊)材料中的应用研究正日益受到人们的重视。铁基自熔合金末作为一种广泛使用的热喷涂(焊)材料具有价格低廉,喷涂(焊)层的耐磨性较好等优点,但其耐蚀性较差。为此,本研究引入稀土对其改性。通过熔炼-雾化工艺制备了稀土铁基自熔合金粉末,并考察了稀土对铁基自熔合金喷焊层在硫化氢介质中气蚀和在含硫化氢的中性氯化钠溶液中浸蚀的影响。结果表明,铁基自熔合金(含稀土和不含稀土)喷焊层试样表现出较强的抗硫化氢能力。铁基合金喷焊层试样在含硫化氢的4Wt%NaCl溶液中的腐蚀速率随稀土的添加量增加量增加而逐渐降低,且稀土添加量有最佳值0.2Wt%。 相似文献
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稀土元素在铝合金转化膜中的应用 总被引:4,自引:0,他引:4
铝合金稀土转化膜具有优异的耐蚀性能和无毒无污染等优点,是最具希望代替铬酸盐有毒处理、有良好发展前景的转化膜之一.本文从成膜工艺、膜的组成、结构及形貌、成膜机理和耐蚀机理四个方面介绍了铝合金稀土转化膜技术在国内外的研究进展及现状,展示了稀土元素在铝合金转化膜中广阔的应用前景,并对这一技术未来的发展方向提出了展望. 相似文献
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Effect of ErCl_3 Addition on Microstructures and Properties of AZ91 Magnesium Alloy 相似文献
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Mechanism of Effects of Rare Earths on Microstructure and Properties at Elevated Temperatures of AZ91 Magnesium Alloy 总被引:2,自引:1,他引:2
By using real-space recursion method,the energetics of the undoped and Al and/or RE atoms doped 7(1450)〈0001〉 symmetric tilt grain boundaries(GBs)in AZ91 alloys were investigated.Similar calculations were performed on undoped and doped bulk α Mg for comparison.The results showed that Al atoms segregated at GBs in AZ91 alloys.When RE atoms were added,they also segregated at GBs,and their segregation is stronger than Al atoms'.Therefore,RE atoms retard the segregation of Al atoms.Calculations of interaction energy indicated that Al atoms repelled each other,and could form ordered phase with host Mg atoms.On the contrary to the case of Al,RE atoms attracted each other,they could not form ordered phase with Mg,but could form clusters.Between RE and Al,there existed attractive interaction,and this attractive interaction was the origin of Al11RE3 precipitation.Precipitation of Al11RE3 particles with high melting point and high thermal stability along GB improves high temperature properties of AZ91 alloys. 相似文献
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The effect of Y-base rare earth alloy in ultra-high hardfacing was observed by means of OM, SEM and XRD. Precipitated carbide can be metamorphosed and spheroidized in surfacing by adding Y-base rare earth alloy, which contributes to the increase of precipitated carbide. Rare earth combined with oxygen and sulfur can improve the morphology of slag inclusion as well as purify surfacing. The result shows proper rare earth alloy in surfacing can fine its microstmcture, improve hardness and impact toughness. 相似文献
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Effects of RE on Microstructures and Mechanical Properties of Hot-Extruded AZ31 Magnesium Alloy 总被引:4,自引:2,他引:4
Effects of rare earth (RE) additions on microstructure and mechanical properties of the wrought AZ31 magnesium alloy were investigated. The results show that, by adding 0.3%, 0.6% and 1.0% RE elements, the as-cast microstructure can be refined, and the as-cast alloys‘ elongation and tensile strength can be improved. After extrusion, the alloy with 0.3 % and 0.6% RE additions obtain a finer microstructure and the best mechanical properties, but the alloy with 1.0% RE addition has the coarse A1-RE compound particles in grain boundaries which decreased elongation and tensile properties. Usually, Rare earth (RE) elements were used to improve the creep properties of aluminium-containing magnesium pressure die cast alloys at elevated temperatures. In this paper, it is also found that the high temperature strength of extruded materials can be increased by RE elements additions. 相似文献
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本文论述了稀土镁硅铁合金中主要非金属夹杂物—氧化镁的生成原因及其对应用的危害 ,提出了降低合金中氧化镁的方法。 相似文献