Friction and wear performances of borates and lanthanum chloride in water

The antiwear and friction-reducing performances of sodium borate, potassium borate and lanthanum chloride in water were evaluated on a four-ball friction tester. The topographies, element distribution and chemical characteristics of the worn surfaces were investigated by scanning electron microscope （SEM）, energy dispersion of X-ray （EDX） and X-ray photoelectron spectroscope （XPS）. The results indicated that sodium borate, potassium borate and lanthanum chloride increased extreme pressure, antiwear and friction-reducing capacities of water to a certain extent, of which potassium borate was the best candidate. Combination of lanthanum chloride with sodium borate and po- tassium borate respectively further improved antiwear and friction-reducing capacities. Scratches of worn surfaces lubricated with water containing borates and lanthanum chloride were less severe than those lubricated with water containing borates alone. A tribochemical film mainly composed of oxides of lanthanum, boron and iron reduced friction and wear for water lubricant formulated with both borates and lanthanum chloride.     

CaCl2-NaCl熔盐中La2O3电脱氧反应的电化学研究

采用熔盐电解法研究了La2O3电脱氧反应过程。由电位阶越实验及取样电流电位分析和对电解产物进行X衍射分析表明La2O3的电脱氧反应是可以进行的，La2O3得电子还原为低价脱氧产物LaO，接着LaO作为中间产物与阳极气体Cl结合生成氯氧镧。     

Synthesis and characterization of La（OH）_3 nanopowders from hydrolysis of lanthanum carbide

The lanthanum carbide alloy was induction melted in vacuum induction melting furnace from lanthanum and graphite with the mass ratio of 89:11. Lanthanum hydroxide (La(OH)3) nanopowders were prepared by a simple hydrolysis of lanthanum carbide at room temperature under normal atmospheric pressure without any surfactant. X-ray diffraction (XRD) showed that the nanoparticles were with a hex-agonal structure. The effect factors such as reaction time,reaction temperature and the mass ratio of lanthanum carbide p...     

Nitric oxide(NO) decomposition on catalysts,containing oxides of lanthanum and cerium,supported on γ-alumina

The present work was devoted to study the catalytic activity of lanthanum and cerium oxides separately,deposited on g-alumina in the reaction of decomposition of nitric oxide. The catalyst samples were prepared by the method of impregnation of g-Al_2 O_3 using solutions, containing nitrates of lanthanum and cerium. The prepared samples were calcined for 4 h at temperature 650℃ in an oven in air atmosphere. The catalysts were characterized by: chemical analysis by inductively coupled plasma atomic emission spectrometry(ICP-AES), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM) combined with energy-dispersive X-ray spectroscopy(EDS), electron paramagnetic resonance(EPR) and infrared(IR) spectroscopy, as well as measurement of the specific surface area. The results show that the catalysts based on lanthanum oxide and cerium oxide deposited on alumina display high catalytic activity over 60% conversion degree with respect to decomposition of nitric oxide in the absence of reducing agent. In the presence of reducer the activity reaches 90% conversion degree.     

稀土镧改性磷钨杂多酸盐催化油酸与甲醇酯化反应合成生物柴油活性研究

以H ₃PW ₁₂O ₄₀和La(NO ₃) ₃为原料,通过离子交换法制备一种稀土镧改性磷钨杂多酸盐催化剂.通过扫描电镜、红外光谱和X射线粉末衍射等表征方法,对合成的催化剂的物理及化学性能进行分析,进而通过以油酸和甲醇为反应物的酯化反应,对其催化活性进行研究.结果表明:稀土镧已经导入磷钨杂多酸的骨架结构,并与杂原子P形成配位键,有效提高磷钨杂多酸的比表面积和孔径;合成的催化剂具有完整的Keggin型结构;当反应温度为62 ℃,油酸与甲醇摩尔比为1∶6,反应时间为4.5 h,催化剂用量为反应物质量的2.5 %,油酸的转化率可达88.0 %.      

Preparation and Structure Characterization of Rare Earth Doped Alumina-Siloxane Gel and Its Modification on ER Effect

A series of samples of alumina-siloxane gel wrapped by poly (methyl methacrylate) and doped with rare earths such as lanthanum, praseodymium, yttrium, gadolinium and europium were prepared. The structure features were characterized by micrograph, X-ray fluorescence spectrum, X-ray diffraction spectrum, Fourier transform infrared spectrum and differential thermal analysis.Tests indicate that rare earths modify the electrorheological effects of the stable suspensions composed of samples stirred with silicon oil.     

电解法生产金属镧槽龄初探

介绍了用２０００Ａ设备生产金属镧时，采用铁保护壳石墨电解槽、氟化物熔盐休系电解氧化镧而得到金属镧产品，并提供了判断金属柄寿命的依据。通过生产过程中的观察后，针对该槽的槽龄即槽生产的部天数进行了测算，同时还详细收集了９台槽子的生产数据，并对数据进行了统计分析。     

Studies on Electrolytic Codeposition of Lanthanum-Cobalt in Urea Melt

ＳｔｕｄｉｅｓｏｎＥｌｅｃｔｒｏｌｙｔｉｃＣｏｄｅｐｏｓｉｔｉｏｎｏｆＬａｎｔｈａｎｕｍ－ＣｏｂａｌｔｉｎＵｒｅａＭｅｌｔＱｉｕＫａｉｒｏｎｇ（丘开容），ＹａｎｇＱｉｑｉｎ（杨绮琴）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＺｈｏｎｇｓｈａｎＵｎ...     

熔盐氯化物电解金属中配分镧、铈波动的探讨

文章主要介绍了熔盐氯化物电解金属的过程中,金属配分镧、铈波动产生的原因及在生产实践中解决的办法和注意事项.     

Influence of lanthanum as additive and post-treatment on the corrosion protection properties and surface morphology of mild steel chemically treated by a cerium conversion coating

The influence of cerium conversion coating (CeCC) modified by lanthanum in two forms of additive and post-treatment solution on the corrosion resistance, surface morphology and surface chemistry of the mild steel was studied. Corrosion resistance was evaluated by electrochemical impedance spectroscopy, while the scanning electron microscopy, X-ray photoelectron spectroscopy and contact angle test were employed to investigate the surface characteristics. Results reveal that the CeCC post-treated by lanthanum containing solution gives rise to the deposition of a crack free and uniform conversion coating with enhanced corrosion resistance on the steel surface. Also, the surface free energy is increased after post-treatment.     

镧对碳纳米管负载型Ni-B非晶态合金乙炔加氢性能的影响

采用超声辅助的浸渍-还原法制备了N i-B/CNT s及L a改性的N i-B/CNT s非晶态合金催化剂,运用ICP、XPS、TPR、H2-TPD、CO化学吸附法对催化剂进行表征,并研究了催化剂的乙炔选择加氢性能。与N i-B/CNT s相比,添加适量L a提高了活性N i表面积,增强了N i的富电子性,促进了催化剂还原、氢脱附性能,并具有更好的加氢活性,L a的适宜添加量为5%~8%(质量分数)。     

Photocatalytic Destruction of Nitrogen Monoxide over La^3＋ and N Co-doped SrTiO3 Powders under Visible Light Irradiation

Lanthanun, and nitrogen co-doped SrTi03 was prepared by a mechanochemical reaction using SrTi03, urea and la203 as the raw materials. The samples were characterized by X-ray diffraction, X-ray photoelectron spectrometer, trans-mission electron microscopy, and nitrogen adsorption-desorption isotherm measurements, lanthanum doping could increase the doping content of nitrogen in the sample. The sample prepared with 0.2 mol% La203, 22 mol% urea and 77.8 mol % SrTi03 by mechanochemical reaction, which has nearly the same nitrogen and lanthanum doping fractions, exhibited high photocatalytic activities. Under the irradiation of light with wavelength larger than 400, and 290 nm, the photocatalytic activity of nitrogen and lanthanum co-doped SrTi03 were 2.6 and 2 times greater than that of pure SrTi03.     

An in-situ Raman spectroscopic study on potential-pO~(2-) phase diagram of lanthanum in LiCl-KCl eutectic melt

The oxidative reaction between lanthanum trichloride and oxide ion was studied in the molten LiCl-KCl eutectic at 773 K by in-situ Raman spectroscopy using an yttria-stabilized zirconia electrode in conjunction with electrochemical methods.The formation of lanthanum oxychloride,LaOCl(s),was confirmed by studying the vibrational properties of crystalline LaOCl and X-ray diffraction analysis.The solubility product of LaOCl in the LiCl-KCl molten eutectic at 773 K is found to be pK_(sp)(LaOCl)=7.569±0.100,by combining the results of Raman spectroscopy and potentiometric titration with the addition of barium oxide.The use of Raman spectroscopic quantitation of dissolved lanthanum ions in the system allows faster and more accurate determination of the stable phase of lanthanum as well as the solubility product of LaOCl compared with that measured by potentiometric titration only.Based on experimentally obtained pK_(sp) and standard equilibrium potentials,the potentialpO~(2-) phase diagram of lanthanum in the molten LiCl-KCl eutectic was reported.     

Mechanochemical Reaction of Lanthanum Carbonate with Sodium Hydroxide and Preparation of Lanthanum Oxide Nanoparticle

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Rare earth and silane as chromate replacers for corrosion protection on galvanized steel

The present work aimed at using rare earth lanthanum salt and trimethoxy(viny)silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate. The corrosion resistance was assessed by electrochemical impedance spectroscopy (EIS) and neutral salt spray tests (NSS). Scanning electron microscopy (SEM) was used to characterize the sample surfaces. The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests. The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion. The coating formation mechanism was also discussed.     

Characterization and bacterial toxicity of lanthanum oxide bulk and nanoparticles

This study evaluated the bacterial toxicity of lanthanum oxide micron and nano sized particles using shake flask method against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. Particle size, morphology and chemical composition were determined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Re-sults indicated that lanthanum oxide nanoparticles showed antimicrobial activity against Staphylococcus aureus, but not against Escherichia coli and Pseudomonas aeruginosa. It was speculated that lanthanum oxide produced this effect by interacting with the gram-positive bacte-rial cell wall. Furthermore, lanthanum oxide bulk particles were found to enhance the pyocyanin pigment production in Pseudomonas aeruginosa.)     

Influence of Lanthanum on Tribological Properties and Microstructure of Laser Clad B ＋ Fe ＋ Si Composite Coatings

The effects of rare earth ferrosilicon on the microstructure and anti-wear properties of laser-clad Fe-based alloy coating were investigated. The composition of Fe, B4C and rare earth ferrosillcon powders with different contents of lanthanum were clad onto a 45 # carbon steel substrate. Microstructural features, chemical compositions, phase structure,hardness, friction and wear properties by scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS),hardness tester, block-on-ring friction and wear tester of the clad coating were determined. Experimental results show that the friction coefficient of the clad coating doped with rare earth ferrosilicon is reduced while the wear resistance of clad coating doped with rare earth ferrosilicon is enhanced. When the content of lanthanum increases to 1.92%, the clad coating shows the best anti-wear ability, and as the content of lanthanum exceeds 1.92%, the wear weight loss increases quickly. The rare earth ferrosilicon to be doped in the clad coatings helps to disperse the boride phase (Fe2B, FeB, B4C)particles and refine the grain of boride phase. The enhancement of clad coating‘s wear resistance is due to the existence of dispersed boride phases.     

Influence of lanthanum doping on performance of LiFePO4 cathode materials for lithium-ion batteries

Using solid-state synthesis method,a series of samples of lanthanum doped Li1-xLaxFePO4(x=0.0025,0.005,0.0075,0.01) were prepared.Each cathode structural and electrochemical properties were investigated using X-ray diffractometry(XRD),scanning electron microscopy(SEM),electrochemical impedance spectroscopy(EIS) and charge/discharge cycling.Nanopowders material with single-phase could be obtained.The reversible capacity could be drastically improved by the introduction of La.The optimum cells with Li0.99La0....     

LaCl3-KCl熔盐体系物化性质研究

合理选择熔盐体系在电解法制备稀土金属工业生产过程中至关重要。文中采用阿基米德法、拉筒法和连续变电导池常数法（CVCC）测定了不同配比的LaCl₃-KCl熔盐在1 073~1 223 K下的密度、界面张力和电导率。结果表明,随着温度升高,相同成分的LaCl₃-KCl熔盐的密度（ρ）和界面张力（σ）均呈降低趋势,而电导率（κ）逐渐增大;在相同温度下,随着LaCl₃含量增加,LaCl₃-KCl熔盐的密度和界面张力均逐渐增大,而电导率逐渐减小。通过拟合获得密度、界面张力以及电导率的经验公式分别为ρ=a-b×T×10-3、σ=a-b×T×10-3、κ=A+B×T×10-3+C×T2×10-6,明晰了熔盐的物化性质随温度及组分的变化规律,为熔盐电解法制备镧及其镧合金提供科学依据。      

Effect of Lanthanum on Mycelium Growth and Some Pathogenic Factors

Three soil-transmitted pathogenic fungi including Rhizoctonia solani, Fusarium solani, and Pythium sp. were selected to investigate the effect of lanthanum on their growth and the pathogenic enzymes using liquid culture. Variance analysis shows significant differences among treatments with different concentrations of lanthanum （Rhizoctonia solani F = 6.75 〉 F0.01= 5.99; Fusarium solani F = 18.1 〉 F0.01 = 5.99, Pythium sp. F = 23.29 〉 F0.01 = 5.99）. The inhibitory effect of lanthanum on pathogenic fungi increased with an increase in La concentration. The activities of the three pathogenic enzymes per gram mycelium were promoted remarkably. However, the quantity or the activities of the total enzymes were inhibited because of the strong inhibition of mycelium growth by lanthanum. Meanwhile, the effect of lanthanum on toxins of pathogenic fungi were studied using the seed germination experiment. Toxins of pathogenic fungi are influenced by lanthanum and the virulence decreases significantly with the increase of lanthanum concentration.