Improving Corrosion Resistance of Cf/Mg Composites using Rare Earth Conversion Coatings

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.     

Investigation of Formation and Inhibition Mechanism of Cerium Conversion Films on Al 2024 Alloy

To study the mechanism of formation and inhibition of Ce conversion films on A1 2024-T3 alloy, scanning microreference electrode technique (SMRE) is used to probe the potential map on A1 2024-T3 in CeC13 solution, the localized corrosion of A1 alloy decreases with immersion time and disappears finally, which results from the competition of Cl^- aggression and Ce^3 inhibition on alloy surface. The results of X-ray photoelectron spectroscopy (XPS) indicate that the Ce conversion films consist of Al2O3, CeO2 and Ce2O3 (Ce(OH)3), and CeO2/Ce2O3 ratio decreases with the immersion time. When a critical pH for Ce(OH)3 formation was reached, Ce(OH)3 will precipitate on the micro cathodic area on alloy surface. Consequently, H2O2, the product of the catholic reaction will oxidize a part of Ce(OH)3 to CeO2, which appears a better corrosion resistance for Al alloys.     

用循环阳极极化曲线评价Al6061/SiCP复合材料表面稀土转化膜耐腐蚀性能的研究

本文提出了利用循环阳极极化曲线研究转化膜耐腐蚀性能的方法。介绍了 Al60 61 /Si CP复合材料表面稀土转化膜工艺。将稀土转化膜与其它转化膜的耐腐性能进行了比较。利用循环阳极极化曲线的“相对环面积”研究转化膜耐腐蚀性能能够得出很好的规律性。     

稀土对Al2O3陶瓷涂层组织及性能的影响

采用等离子喷涂方法制备Ａｌ２Ｏ３陶瓷涂层,研究了稀土对涂层组织及耐蚀性的影响。结果表明,在喷涂粉末中添加适当的稀土硅铁合金不仅可以改变涂层显微组织、减少和消除层状结构,而且显著提高了涂层的耐蚀性。     

Corrosion Behavior of Electrodepositing Ni/Al2O3 Composite Coatings under the Presence of NaCl Deposit

The morphology and corrosion behavior of Ni/Al2O3 composite coatings prepared using double-pulsed electrodepositing technique after oxidized under 800℃ NaCl deposit in air environment were analyzed by scanning electrical microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrum (EDS). The results showed that the corrosion of all composite coatings was accelerated under NaCl deposits, and the corrosion products were rather porous with poor adherence to the matrix. Al2)O3 particles in the coatings can refine the grain size and improve the high temperature corrosion resistance of the coatings. Within the test scope, the more Al2O3 particles in the coatings, the lower corrosion rates could be obtained, and the corrosion mechanism was also discussed.     

等离子喷涂Al/BN涂层工艺研究

采用正交实验设计方法研究了等离子喷涂Al/BN涂层过程中涂层硬度、化学成分与等离子喷涂参数之间的响应关系,利用建立的响应公式,通过排列组合,优选出最佳工艺参数,并进行了验证。在实验参数区间内:涂层布氏硬度与氩气流量、氢气流量及电流成正比,与喷涂距离及送粉速率成反比;BN含量与氩气流量、氢气流量、电流、送粉速率及喷涂距离成反比;SiO2含量与氩气流量、氢气流量、电流成正比,与送粉速率和喷涂距离成反比。在最优工艺参数范围下:获得的涂层硬度压痕直径在5.5~6.1之间,涂层结合强度均值≥4.0MPa,涂层经100小时,450℃热处理后的硬度值在5.5~6.2之间,制备的涂层能满足航空发动机长期使用需求。     

Effect of Cerium on Chemical Short Range Order of Al-Fe-Ce Amorphous Alloy

Ｉｎｒｅｃｅｎｔｙｅａｒｓ,Ｈｅｅｔａｌ.[1]ａｎｄＩｎｏｕｅｅｔａｌ.[2]ｄｉｓｃｏｖｅｒｅｄａｇｒｏｕｐｏｆａｍｏｒｐｈｏｕｓａｌｌｏｙｓｗｉｔｈａｌｕｍｉｎｕｍｃｏｎｔｅｎｔｃｌｏｓｅｔｏ90%(ａｔｏｍｆｒａｃｔｉｏｎ),ｗｈｉｃｈｐｏｓｓｅｓｓｅｘｃｅｌｌｅｎｔｓｐｅｃｉｆｉｃｓｔｒｅｎｇｔｈｉｎＡｌＴＭＲＥ(ＴＭ=ｔｒａｎｓｉｔｉｏｎｍｅｔａｌ)ｓｙｓｔｅｍｓ.Ｔｈｅｙｈａｖｅｕｐｔｏ500～1100ＭＰａｉｎｓｔｒｅｎｇｔｈａｎｄｇｏｏｄｄｕｃｔｉｌｉｔｙ.Ｈｏｗｅｖｅｒ,ｔｈｅｏｒｉｇｉｎｏｆＡｌｂａｓ…     

电沉积RE-Ni-W-P-SiC复合镀层的耐蚀性研究

本文提供了RE-Ni-W-P-SiC复合材料在不同浓度的H2S04、nCI、H3PO4和FeCl2溶液中的腐蚀速率。试验结果表明该复合材料比不锈钢316L有更好的耐蚀性。     

Effect of Cerium on Microstructures and High Temperature Oxidation Resistance of An Nb-Si System In-Situ Composite

Nb-16Si-24Ti-6Cr-6A1-2Hf-xCe （x =0, 0.05, 0.1,02.5, 0.5, 1 （%, atom fraction）） in situ composites were prepared by arc melting The microstmcture and the effect of rare earth element cerium on 1250℃ oxidation resistance of the composites were investigated with scanning electron microscopy （SEM） and X-ray energy disperse spectrum （EDS）, as well as X-ray diffraction （XRD）. The experimental results showed that the high temperature oxidation resistance of the alloy was improved by adding a proper amount of cerium （Ce）. The effect of Ce was considered as the concurrent of the following three factors： first, the oxide of Ce formed in the interface reduced the internal oxidation rate; second, the lath shaped oxide containing Ce increased the cracking resistance and reduced the expansion of the oxide scale; and third, the decrease of the sificide volume fraction on account of Ce addition reduces the power of the sample resisting oxygen penetration.     

Effects of Cerium Oxide on Ni／Al2O3 Catalysts for Decomposition of CH4 and C2H4

Characteristics of carbon deposition of CH4 and C2H4 decomposition over supported Ni and Ni-Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It is found that there is a metal-semiconductor interaction (MScI) in the Ni-Ce catalyst, and the effect of MScI on the carbon deposition of CH4 decomposition is opposite to that of C2H4. A novel model of carbon deposition of CH4 or C2H4 decomposition was proposed.     

WC-Fe3Al表面耐磨复合材料的研制

用药芯焊丝法制得WC-Fe3Al复合焊材,将该焊材堆焊于工件表面,利用氩弧物理热和Fe-Al反应热使碳化物硬质颗粒与Fe3Al金属间化合物复合,从而在焊层中形成碳化物颗粒强化的Fe3Al基复合材料.微观组织观察与XRD相分析表明,堆焊过程中WC颗粒发生分解,析出弥散分布的细小W2C相.基体相组成受WC-Fe3Al复合药芯焊丝制备时Fe/Al配比的影响,主要为Fe3Al相,但当Fe/A1配比不适当时会出现部分α-Fe.碳化物的弥散强化作用显著提高了Fe3Al基复合材料的硬度和耐磨性,使该材料成为一种有工业化应用前景的新型高温耐磨表面强化材料.     

稀土铈对化学沉积Co-Ni-B合金镀层结构和性能的影响

研究了稀土铈对化学沉积Co-Ni-B合金层化学组成、结构和性能的影响。结果表明：微量稀土铈的加入提高了镀层中钴的含量，降低了镍和硼的含量；使镀层由非晶态转变为品态；稀土铈也明显地提高了镀层的显微硬度，在一定的范围内，镀液中稀土铈添加量越多，镀层的铈含量和显微硬度也越高；稀土铈还提高了镀层的饱和磁化强度，降低了剩余磁化强度和娇顽力，含铈镀层显示出了良好的软磁性能。     

Preparation and Performance of Rare Earths Chemical Conversion Film on Magnesium Alloy

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.     

TiAl涂层对Ti3Al合金的热腐蚀防护

利用磁控溅射的方法在Ti3Al合金上溅射Ti-48Al-8Cr-2Ag涂层,研究涂层对Ti3Al合金热腐蚀行为的影响。热腐蚀采用浸盐法,在900℃25%Na2SO4+75%K2SO4熔盐中进行,利用带能谱的扫描电镜(SEM/EDX)对腐蚀膜进行观察分析。结果表明,在熔盐热腐蚀中,Ti3Al合金表面发生大面积脱落,而涂层试样表面腐蚀膜结合牢固。涂层对基体具有很好的防护作用。     

喷射沉积SiCP/Al复合材料及6066铝合金热挤压工艺的研究

作者应用喷射共沉积工艺制备 6 0 6 6 / Si Cp复合材料和 6 0 6 6铝合金锭坯 ,在不同的挤压比、挤压温度下挤压成　　型 ,用金相显微镜观察材料的显微组织 ,并测试了材料的力学性能。结果表明 :Si C/ Al复合材料喷射沉积状态的组织很疏松 ,存在许多的间隙 ,其密度约为理论密度的 86 % ,Si C颗粒在复合材料中分布不均匀 ,喷射沉积铝合金基体的致密度可达 90 % ;挤压过程使 Al/ Si Cp复合材料的大多数空隙消失 ,致密程度随挤压比的增大而增大 ,挤压比超过 14 .7后不会明显变化 ,而铝合金基体的致密程度与挤压比的变化关系不明显 ;挤压温度对材料的致密程度影响不大 ;Al/ Si Cp复合材料性能在挤压比超过 14 .7后变化不大 ;铝合金的性能不受挤压比变化的影响 ;而挤压温度过高使材料性能下降     

Investigation of rare earth sealing of porous micro-arc oxidation coating formed on AZ91D magnesium alloy

Magnesium and its alloys have been used in many industries, but they are reactive and require protection against aggressive envi-ronments. In this study, oxide coatings were applied on AZ91D magnesium alloy using micro-arc oxidation (MAO) process. Then, in order to seal the pores of the MAO coatings, the samples were immersed in cerium bath for different times. The surface morphologies and composi-tions of the coatings were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS), respectively. The corrosion behavior of the coatings was investigated with electrochemical impedance spectroscopy (EIS) and potentiodynamic polariza-tion tests in 3.5 wt.% NaCl solution. The amount of the porosity of the coating was measured by electrochemical method. It was found that the sealing treatments by immersion in cerium bath successfully sealed the pores of the MAO coatings. The results of the corrosion tests showed that the MAO coating which was sealed in Ce bath for 10 min enhanced the corrosion resistance of the substrate significantly. Fur-thermore, this coating had the lowest amount of the porosity among the coatings.)     

锌和镀锌钢的稀土表面改性

通过在Ce(NO_3)_3水溶液中对锌和电镀锌钢进行化学转化(钝化)处理,在试样表面形成了铈转化膜。利用电子探针显微分析(EPMA)、X射线光电子能谱(XPS)和X射线衍射(XRD)等研究了转化膜的形貌、成分和结构,探讨了锌表面铈转化膜的形成机理。在氯化钠溶液中测定了试样的腐蚀率、极化曲线和电化学交流阻抗谱(EIS)等腐蚀性能参量,并与未钝化和普通铬酸盐钝化试样的情况作了对比。结果表明,本实验得到的锌表面稀土转化膜主要是由CeO_2、Ce_2O_3和ZnO组成的复合氧化物膜,铈转化膜的存在阻碍了锌在电化学腐蚀过程中的阴极反应和阳极反应,导致电荷传递电阻增大,腐蚀率降低。在一定条件下,铈转化膜对锌和镀锌钢的肪蚀效果优于铬酸盐转化膜。     

Influence of Cerium on Corrosion of AZ91 Magnesium Alloy

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.     

Influence of Surface Gas-Phase Rare Earth Permeation Plus Laser Melting Solidification on Microstructure and Corrosion Resistance of Pure Iron

Ａｓｏｎｅｐｒａｃｔｉｃａｌａｐｐｌｉｃａｔｉｏｎｏｆｓｕｒｆａｃｅｍｏｄｉｆｉｃａｔｉｏｎｂａｓｅｄｏｎｌａｓｅｒｔｅｃｈｎｉｑｕｅ ,ＲＥ ｌａｓｅｒａｌｌｏｙｉｎｇｈａｓｂｅｅｎｗｉｄｅｌｙｉｎｖｅｓｔｉｇａｔｅｄａｎｄｒｅｐｏｒｔｅｄ[1] .Ａｌｔｈｏｕｇｈｔｈｅｔｒｅａｔｍｅｎｔｏｆｓｕｒｆａｃｅｇａｓ ｐｈａｓｅＲＥｐｅｒｍｅａｔｉｏｎｈａｓｂｅｅｎｐｒｏｖｅｄｔｏｂｅｅｆｆｅｃｔｉｖｅｏｎｉｍｐｒｏｖｉｎｇｓｕｒｆａｃｅｈａｒｄｎｅｓｓ ,ａｂｒａｓｉｖｅｒｅｓｉｓｔａｎｃｅａｎｄｃｏｒｒ…     

Preparation and Corrosion Resistance of Rare Earth Conversion Coatings on AZ91 Magnesium Alloy

Magnesiumalloysarewidelyusedinweaponin dustry,spacenavigationandhavegoodpotentialof applicationanddevelopmentindailycommunication facilitiesduetotheirpropertiesoflightweightandhighstrength[1].Appliedasstructuralmaterials,mag nesiumalloysmayeasilycrackduet…