Study on corrosion resistance of the BTESPT silane cooperating with rare earth cerium on the surface of aluminum-tube

Bis-3-(triethoxysilyl)propyltetrasulfide(BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method.The performance of composite coatings to protect the aluminum-tube against corrosion was investigated with potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),and salt spray test(SST).The results of potentiodynamic polarization curves and EIS indicated that the self-corrosion current decreased by two orders of magnitude and the i...

Influence of rare earth cerium on the microstructures and performances of Al-Fe alloy

The effects of rare earth addition on the microstructures as well as the tensile performances and electrical conductivity of Al alloys have attracted increasing attention recently.However,little research has been carried out to investigate the influence of minor Ce(the Ce additive amount is below 0.1 wt.%).In this study,experiments have been performed to explore the effects of minor Ce on the microstructures as well as the tensile properties and the electrical conductivity of Al-Fe alloy.The results demonstrate that minor rare earth Ce addition not only leads to the α-Al refinement and the modification of Al_(13)Fe_(4) minority phase,but also decreases the solid solubility of Si.The grain refinement induced by Ce addition has a negligible influence on the tensile strength and yield strength,while the ductility and conductivity can be simultaneously ascended by adding rare earth Ce.The modification of Al_(13)Fe_(4) minority phase is responsible for the increment of ductility,and the diminution of Si solid solubility in the Al matrix leads to the increase of electrical conductivity.This work provides a strategy for concurrently improving the tensile performances and electrical conductivity of aluminum alloy.

Effect of Rare Earths on Plant under Supplementary Ultraviolet-B Radiation: Ⅰ Effect of Cerium on Growth and Photosynthesis in Rape Seedlings Exposed to Supplementary Ultraviolet-B Radiation

Effect of cerium （Ce^3＋） on growth and photosynthesis in rape seedlings exposed to two levels of ultraviolet-B radiation （UV-B, 280 - 320 nm） was studied with hydroponics under laboratory conditions. The growth of rape seedlings exposed to two levels of UV-B irradiation （0.15 and 0.35 W· m^-2/T2） was both heavily restrained. The aboveground growth indices including stem （plant） height, leaf number, leaf area, leaf fresh/dry weight and stem fresh/dry weight were obviously decreased by 13.2% - 44.1% （T1） and 21 .4% - 49.3% （T2）. Compared to CK, and except active absorption area of roots, the belowground indices main root length, root volume and fresh/dry weight by 14.1% -35.6% （T1） and 20.3% - 42.6% （T2）, respectively. For Ce ＋ UV-B treatments, the aboveground and belowground growth indices were decreased by 4.1% - 23.6%, 5.2% -23.3% （Ce＋T1） and 10.8% -28.4%, 7.0% -27.8% （Ce ＋T2）, lower than those of UV-B treatments mentioned above. These results show that Ce has protective effect on plant against injury of UV-B radiation. Furthermore, the protective effect of Ce on seedlings exposed to T1 level of UV-B radiation is superior to T2 level. Chlorophyll content, net photosynthesis rate, transpiration rate, stomatal conductance and water use efficiency in UV-B treatments decrease dramatically, whereas intercellular CO2 concentration increases. Although these indices in Ce ＋ UV-B treatments decrease compared with those of CK, the decrease in Ce ＋ UV-B treatments are lower than those in UV-B treatment. This phenomenon indicates that the ecophysiological protective effect of Ce is based on improving photosynthesis in plants. The dynamic curves of photosynthesis indices show that the course of light-repair is shortened and the injury to rape seedlings by UV-B radiation stress is alleviated by Ce.

Corrosion behavior of rare earth cerium based conversion coating on aluminum alloy

The present paper focused on the use of the salt of rare earth cerium as corrosion inhibitor of aluminum by using cathodic electrolytic passivation method.The corrosion resistance and the microphology of the cerium passivation film were studied by the methods of electrochemical method,scanning electron microscopy(SEM),and energy dispersive spectroscopic analysis.From the results,it was shown that good corrosion resistance of cerium-based passive coating was obtained when the compositions were as follows:CeCl3·7H2O,0.05 mol/L;H2O2,30 ml/L;current density,1.1 mA/cm2;temperature,40 oC;time,9 min.SEM and EDS revealed that the cerium conversion coatings formed on the surface of aluminum alloy were related to cerium hydroxide/hydrated oxide depositions.

Modifying Behaviors of Ultrasonic Irradiation and Rare Earth Metal Cerium on Electroless Co-Ni-B Alloy Coating

By plasma transmitting spectrograph,electron energy spectrometry,X-ray diffractometry,transmission electron microscopy and micro-hardometry,the effects of ultrasonic irradiation and rare earth metal cerium on the depositing speed,chemical composition,crystal structure and microhardness of electroless Co-Ni-B alloy coating were inspected and analyzed. The results show that cerium and ultrasonic irradiation can evidently raise the depositing speed of electroless Co-Ni-B alloy. The cerium content of electroless Co-Ni-B-Ce alloy coating also increases after ultrasonic irradiation applied to electroless Co-Ni-B plating process. Under the action of ultrasonic irradiation and rare metal cerium,the chemical composition of electroless Co-Ni-B alloy coating is changed. Electroless Co-Ni-B alloy with amorphous structure is transformed to electroless Co-Ni-B-Ce alloy with microcrystalline in general state and electroless Co-Ni-B-Ce alloy with crystalline structure in ultrasonic irradiation. In this way microhardness of the coatings increases remarkably.

Cerium Separation from Light Rare Earth Concentrate by Liquid-Liquid Extraction

This work presents an investigation of solvent extraction parameters in order to obtain high purity cerium from a mixture containing other rare earths elements, as an alternative to oxidation and selective precipitation or dissolution. The study was carried out using a sample of sulfuric liquor obtained from the leaching of monazite rich in light rare earth elements (La, Ce, Pr, Nd) provided by INB (Indústrias Nucleares do Brasil S.A.). Experiments were carried out in chloridric, nitric and sulfuric media. The nitric and hydrochloric solutions were prepared by precipitation of the REE from the sulfuric liquor as rare earths oxalate, calcining the precipitate and dissolving it with nitric or hydrochloric acid. The separation of cerium was investigated in its trivalent and tetravalent forms. The parameters investigated were: type and concentration of extractant, type and amount of the oxidizing agent, liquor acidity, and volumetric ratio between organic and aqueous phases. The preference of the organic phase to extract cerium in its oxidized form (IV) over the other rare earths elements was confirmed, allowing the obtainment of a high purity cerium solution. The best results were achieved in nitric medium, with cerium in its tetravalent form, using cationic extractants (P507 or D2EHPA) and a mixture of potassium persulfate and silver chloride as oxidizing agents, yielding over 99% of cerium extraction with over 99% of purity.

Synthesis and Photocatalytic Activity of TiO_2/V_2O_5 Composite Catalyst Doped with Rare Earth Ions

TiO2/V2O5 catalyst doped with rare earth ions was prepared by sol-gel method. Titanium tetrapropoxide and vanadium pentoxide were used as precursor of the composite catalyst and rare earth ions were used as dopant. The crystal phases, crystalline sizes, microstructure, absorption spectra of doped composite catalyst were studied by XRD, EDS, FT-IR and UV-Vis. Photoactivity of the prepared catalyst under ultraviolet irradiation were evaluated by degradation of methyl orange （MO） in aqueous solution. It is shown that the prepared catalyst is composed of anatase and futile. The rare earth ions are highly dispersed in composite catalyst. All the doped catalysts appear higher photocatalytic activity than TiO2/V2O5 catalyst and catalyst doped with Ce^4＋ present the best activity to MO.

Synthesis and Crystal Structure of Rare Earth Complex withCiprofloxacin

The complex of rare earth with ciprofloxacin has been synthesized and characterized by means of x-ray single crystal diffraction. The structure features of the complex are decribed.

Adsorption of Ce(Ⅳ) Anionic Nitrato Complexes onto Anion Exchangers and Its Application for Ce(Ⅳ) Separation from Rare Earths(Ⅲ)

Ce （Ⅳ） nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine （PVP） and quatemized PVP incorporated into porous silica matrix. The effect of nitric acid concentration （0.5～6 mol·L^-1） and temperature （278 ～318 K） on Ce（ Ⅳ ） sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce（NO3）6]^2- complex is the main adsorbed Ce（Ⅳ） species. Oxidation of sorbents by adsorbed Ce （ Ⅳ ） species resulting in Ce （ Ⅲ ） release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce（ Ⅳ ） reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce （ Ⅳ ） from La （ Ⅲ ） and Y （ Ⅲ ） was carried out from 6 mol·L^-1 nitric acid with PVP based anion exchanger. Reasonable Ce （Ⅳ） breakthrough capacity （0.7 mol·kg^-1 PVP） was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce （Ⅲ） leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L^- 1 nitric acid was successful （recovery 100% ± 4% ） and Ce solution of high purity （ 〉 99.97% ） with respect to La and Y content was gained.

Normalized Rare Earth Elements in Water, Sediments, and Wine: Identifying Sources and Environmental Redox Conditions

The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an element-by-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived biogenous detritus and hydrogenous metal oxides. The REE of ancient sediments support their partitioning into these same fractions and further contribute to the identification of the redox geochemistry of the sea water in which the sediments accumulated. The normalized curves of the REE that have been examined in several South American wine varietals can be interpreted to reflect the lithology of the bedrock on which the vines may have been grown, suggesting limited fractionation during soil development.

Geochemical Characteristics and Behaviors of Rare Earth Elements in Process of Vertisol Development

Vertisol developed on argillaceous rocks has its special pedogenic processes and properties, and formed some secondary nodules. In study area, contents of rare earth elements (REE) are significantly different in different sedimentary rocks due to varied contents of clay fraction and clay mineral composition, etc. Under the dry and hot climate, REEs were less differentiated than their parent sedimentary rocks. However, REEs in secondary nodules formed in pedogenic process display their specific behaviors. They are more concentrated in iron concretions, the content of heavy REEs increases relatively, and positive Ce-anomaly appears. But, negative Ce-anomaly was found in calcium concretions, while normal Ce content in parent rocks and vertisol.

Corrosion Inhibition Mechanism of Rare Earth Metal on LC4 Al Alloy with Spilt Cell Technique

A new method of studying the corrosion inhibition mechanism of rare earth metal（REM） on LC4 Al alloy with the spilt cell technique was studied. The principle and experimental method of the spilt cell technique were analyzed. By measuring the change of net-electric current between the two electrodes caused by the change of the amount of oxygen in the solution and the addition of CeCl3, the influence of corrosive performance of CeCl3 on LC4 super-power aluminum ＂alloy in the 0.1 mol· L^-1 NaCl solution was investigated. Meanwhile, the conditional changes of pH values, CeCl3 solution, additire and time of performance were also studied. Finally, the features of electrode surface were revealed by using SEM and X-ray energy-dispersive spectrometry （EDS）. By combining these with other electric chemical techniques, such as potential-time curve, polarization curve et al.

Preparation and Characteristics of Rare Earth Loaded Titanium Dioxide

Composite oxide catalysts Eu/TiO 2, Ce/TiO 2, Y/TiO 2 (RE/TiO 2) were prep ared by impregnation method and characterized by means of UV-Vis spectroscopy, TEM and BET. The results indicate that the size of TiO 2 has different effect o n the modification effic iency. The catalytic activity of micron scale TiO 2 increases by 136% and 59% o w ing to the addition of Y and Ce, respectively, while the catalytic activity of n anoscale TiO 2 decreases due to the doping of Y and Ce.

Synthesis and Performance of Titanium Organic Gel Doped with Rare Earth

White nano-titanium organic compound-gel with steady performance was synthesized by sol-gel method. This gel has good absorbency to ultraviolet rays. Specially, the absorption wavelength of the organic gel shifted from 250.9 to 254.3 nm(doped with La) and 257.8 nm(doped with Ce), respectively and the absorption peak broadened. The broadening extent has direct ratio with the doping content. It is indicated that when the thickness of the organic gel coat is 60 μm, 98.8% ultraviolet with radiation intensity of 17.2 μW·cm -2 is blocked off. The TEM test shows that the diameter of the titanium organic gel doped with lanthanum is about 5 nm and the granules are uniform. It is indicated that by X-ray this organic substance is amorphous state and it will form nano-TiO_2 with anatase structure calcined at 450 ℃.

稀土萃取分离流程中Ce(Ⅳ)分布规律及抑制方法研究

近年来,稀土冶炼分离企业在萃取提纯镨钕系列化合物的过程中普遍出现了铈组分分离顺序错位的现象。目前,尚未见到关于稀土萃取流程中各功能段有机相中Ce(Ⅳ)分布规律以及稀释剂选型与稀土冶炼过程铈组分分离顺序错位的关联性相关报道。鉴于此,以稀土分离流程中经典的铈镨分离工艺作为理论模型,系统研究了各萃取功能段Ce(Ⅳ)分布规律与影响因素,对稀释剂化学组成和化学特性进行了分析,同时测定了不同稀释剂对有机相中Ce(Ⅳ)的抑制作用。研究结果表明,稀土萃取分离过程中的水相酸度、元素配分、萃取级数等对各分离段有机相中Ce(Ⅳ)含量影响明显。稀释剂选型对稀土萃取分离过程有机相中Ce(Ⅳ)的抑制作用受其化学组成的影响,其抑制作用依次为:煤油>磺化煤油>溶解油,实际工业化生产过程中可通过补加适量的高溴值煤油或调整稀释剂中某些有效成分来抑制有机相中Ce(Ⅳ)的生成。该研究对后续工艺改进、确保稀土萃取分离过程镨钕系列产品质量稳定具有一定的指导意义。

含铈半固态ZL105合金组织及耐腐蚀性能研究

通过光学显微镜、扫描电子显微镜、能谱分析仪、显微硬度测试、盐溶液浸泡腐蚀及电化学工作站等分析测试方法研究了不同稀土铈添加量对半固态ZL105合金微观组织形貌及耐腐蚀性能的影响。研究结果表明:随着稀土铈含量的不断提高,ZL105合金组织内的初生α-Al相的尺寸逐渐缩小;当铈的含量为0.6%时,合金中初生α-Al相晶粒尺寸为65.77μm,晶粒平均形状因子为0.74,与不添加稀土铈的ZL105合金相比α-Al相晶粒尺寸(115.37μm)降低了42.99%,晶粒平均形状因子(0.42)提高了76.19%。与不含稀土铈的ZL105合金相比,添加了0.6%稀土铈的合金维氏硬度提高了31.64%。稀土铈的添加也大幅提高了合金的耐腐蚀性能,铈的含量为0.6%时合金的失重腐蚀速率为10.85 mg·cm^(-2)·d^(-1),相比于不含稀土铈的合金降低了50.93%,合金的腐蚀电位有所增大并且腐蚀电流密度有所减小。通过腐蚀表面形貌观察可知添加稀土铈的合金的腐蚀凹坑及腐蚀裂纹明显减少,腐蚀表面逐渐变得平整且光滑,腐蚀形貌得到了极好的改善。

硫酸高铈添加剂对超薄电解铜箔结构和力学性能的影响

为提升超薄电解铜箔的力学性能,通过在电解液中添加不同质量浓度的硫酸高铈,研究其对超薄电解铜箔结构和力学性能的影响。结果表明:当Ce(SO_(4))_(2)质量浓度为15 mg/L时,所制备的超薄电解铜箔抗拉强度为457 MPa,延伸率为5.23%,较未添加的电解铜箔抗拉强度和延伸率分别提升了16%和78%,这是因为Ce(SO_(4))_(2)的加入增大了铜电沉积过电位,加快了铜离子在阴极表面扩散速率,Ce^(4+)为Cu^(2+)的沉积提供了活性位点,使得铜晶核大量生成,抑制铜晶体生长,细化铜晶体晶粒大小。Ce(SO_(4))_(2)的加入可改善超薄电解铜箔形貌结构以及提升其力学性能。

镧铈稀土对Al-Si-Mg铸造铝合金性能影响研究

以Al-Si-Mg铸造铝合金为研究对象,研究镧铈混合稀土及其成分含量对铸造铝合金Al-Si-Mg的显微组织和力学性能的影响,结果表明:加入镧、铈稀土后,铝合金组织对比普通的Al-Si-Mg铸造铝合金晶粒呈现明显细化状态,晶枝缩小;添加La、Ce稀土的Al-Si-Mg铝合金力学性能和硬度随稀土含量的增加而增大,但到一定程度后会下降,其中混合镧铈含量为0.1%(质量分数)时,铝合金力学性能最佳,可达到330 MPa的抗拉强度、HBW-93的硬度和4%的延伸率.

2198铝锂合金稀土铈化学转化膜的制备及耐蚀性研究

2198铝锂合金具有较高的比强度及比刚度,在航空航天领域有广泛应用,但其局部腐蚀敏感性较高,需进行适当的表面处理以提高其耐蚀性能。通过化学浸泡法将2198铝锂合金放入0.02 mol/L CeCl_(3)+0.029 mol/L H_(2)O_(2)水溶液中分别处理20、60 min,在其表面获得了稀土化学转化膜。使用扫描电镜(SEM)和能谱仪(EDS)观察和分析了稀土化学转化膜的形貌和成分;用X射线光电子能谱(XPS)分析了转化膜的元素价态;通过测试动电位极化曲线、电化学阻抗能谱(EIS)和Mott-Schottky(M-S)曲线研究了稀土化学转化膜在0.1 mol/L NaCl溶液中的腐蚀行为及耐蚀机制。结果表明:2198铝锂合金稀土化学转化膜由Ce^(4+)和Ce^(3+)的氢氧化物和氧化物、Al~(3+)的氧化物和少量的单质Cu组成,各元素在表面均匀分布;稀土化学转化膜由表面到内部氢氧化物含量减少,氧化物含量增加。处理20 min和60 min获得的稀土化学转化膜的厚度约为0.81μm和1.50μm。在0.1 mol/L NaCl溶液中,稀土化学转化处理能够抑制2198铝锂合金的阴极吸氧过程,降低合金的自腐蚀电流密度,提高合金的耐蚀性;在2198铝锂合金表面制备稀土化学转化膜能使合金的耐蚀性能提高;且与处理20 min的试样相比,处理60 min获得的稀土化学转化膜的耐蚀性较高。同时,稀土化学转化处理改变了合金的腐蚀机制,使与Cl~-吸附相关的感抗弧消失,这是由于具有n型半导体特征的稀土化学转化膜中的载流子密度降低,载流子密度呈现正电荷,不利于Cl~-的吸附。

ICP-AES测定稀土强化黑色二氧化钛中镧铈钇的方法研究

采用HF-HNO_(3)混合酸作为消解试剂,选择Y(360.073 nm)、La(408.672 nm)、Ce(413.380 nm)为分析线,建立了电感耦合等离子体原子发射光谱法测定稀土强化黑色二氧化钛中La、Ce、Y这3种稀土元素的方法。通过系列实验,探讨了样品消解条件、基体效应、共存元素干扰,分析谱线选择等对待测元素测定的影响。结果表明:当试样溶液中待测元素浓度低于5.0 mg/L时,基体钛对待测元素有影响,须采用基体匹配消除影响;共存元素干扰实验表明,当各共存元素溶液低于200 mg/L时,互不干扰测定。各元素方法检出限如下:La为0.0009%,Ce为0.0013%,Y为0.0004%,回收率为97.8%~102.6%,变异系数CV值为0.56%~3.19%;该方法用于测定稀土强化黑色二氧化钛中各稀土元素测定结果与理论值基本一致,测定结果准确可靠。