EXTRACTION KINETICS OF YTTRIUM WITH PURIFIED CYANEX 923 FROM NITRATE MEDIUM

Mass transfer and extraction kinetics of yttrium with the purified Cyanex 923 in n-heptane from nitrate medium have been investigated by using a constant interfacial cell with laminar flow at 298K. The interfacial adsorption properties of purified Cyanex 923-heptane-0.20mol/L (H, Na)NO3 were studied at 298K. The experimental results show that the mass transfer is controlled by diffusion and the chemical reactions are carried out in the interfacial zone. The extraction rates of yttrium were measured at different chemical compositions by varying ionic strength, pH values and the purified Cyanex 923 concentrations. The initial extraction rate equations were obtained.     

EXTRACTION MECHANISM OF CERIUM(IV) AND FLUORINE(I)IN THE SEPARATION PROCESS OF BASTNASITE LEACHSOLUTION BY CYANEX 923

The extraction equilibrium of cerium(IV) and fiuoriue(l) from II2SO4 solution tyCyanex 923 was studied. The extraction mechanism of Ce(IV) and F(I) by Cyanex923 was determined by the method of slope analysis. The results showed that Cyane923 can extract HF as HF.L and Ce4+ together with HF as Ce(HF)(HSO4)2(SO4).2Lby which HF comes into the organic phase mainly when there is Ce4+ in the solution,where L is the extractant. Temperature did not affect the extraction. The IR spectraof purified Cyanex 923 saturated with Ce(IV) and HF were discussed.``     

Phase relationships in lithium-alkaline barth metal systems

The lithium-rich hypoeutectic liquidi and eutectic horizontals of the Li-Ca, Li-Sr, and Li-Ba systems were redetermined by both thermal analytical and resistance-temperature methods. To ensure minimal nonmetal inventories, specimens were gettered using yttrium sponge. The eutectics lie at 142 °C (415 K), 8.0 at.% Ca; 134 °C (407 K), 10.1 at.% Sr; and 141 °C (414 K), 9.9 at.% Ba. All three systems exhibit small positive deviations from ideality with γ_Λι increasing to 1.011, 1.016, and 1.029 for the LiCa, Li-Sr, and Li-Ba systems at the respective eutectic points.     

Phase relationships in lithium-alkaline barth metal systems

The lithium-rich hypoeutectic liquidi and eutectic horizontals of the Li-Ca, Li-Sr, and Li-Ba systems were redetermined by both thermal analytical and resistance-temperature methods. To ensure minimal nonmetal inventories, specimens were gettered using yttrium sponge. The eutectics lie at 142 °C (415 K), 8.0 at.% Ca; 134 °C (407 K), 10.1 at.% Sr; and 141 °C (414 K), 9.9 at.% Ba. All three systems exhibit small positive deviations from ideality with γ_Λι increasing to 1.011, 1.016, and 1.029 for the LiCa, Li-Sr, and Li-Ba systems at the respective eutectic points.     

SEPARATION OF Ce(Ⅳ) AND Th(Ⅳ) FROM RE(Ⅲ) IN HNO_3 SOLUTION BY CYANEX 923 EXTRACTANT

1.IntroductionStraightchainalkylphosphineoxidemixtureCyanex923isonecommercialextractantsdevelopedbyCytecCanadaInc..ComparedwithotherphosphinereagelltsuchasTOPO,theextractatlthajsseveraladvantagesincludinglittleliablehydrolyzation,lowsolubilityinaqueo...     

Contribution of advanced microscopy techniques to nano-precipitates characterization: case of AlN precipitation in low-carbon steel

Aluminum nitride (AlN) precipitation in a Fe–Al–N alloy was studied by Transmission Electron Microscopy (TEM). Crystallographic and chemical properties of precipitates were investigated using electron diffraction, High Resolution TEM, EDX microanalysis, EELS spectroscopy and Energy-Filtered TEM. Observations were carried out on extraction replicas and thin foils. Principally, two varieties of AlN precipitates have been observed: fine cubic (NaCl-type) precipitates with a platelet-like morphology exhibiting a Bain orientation relationship with respect to the α-iron matrix in the case of 3 h annealing at 923 K, and coarse cuboidal-shape hexagonal (wurtzite) precipitates having a particular orientation relationship with respect to the ferrite in the case of 5 h annealing at 973 K. A cubic–hexagonal transformation of AlN nitrides activated by the heterogeneous germination on iron sulfide (FeS) was established. The two AlN varieties were clearly recognized by EELS spectroscopy and the quantification of both populations of precipitates from EFTEM images is discussed.     

Investigation on the mechanism of steel/steel solid-state bonding at low temperatures

The solid-state bonding of ultralow-carbon steels was conducted by hot pressing and subsequent isothermal holding at low temperatures ranging from 873 to 923?K. The evolution of the interfacial strength was found to consist of two stages; the first stage, where the increase in interfacial strength is rapid and significant, and the second stage, where the increase is gradual. The evolution of strength in the first stage primarily takes place in contact regions produced by hot pressing. In the second stage, on the contrary, the evolution seems to result from the increase in the contact regions due to the shrinkage of voids. A molecular dynamics simulation was performed to clarify the atomic behaviour at the interface during the first stage. The results revealed that the disordered atomic arrangement caused by compression was rearranged with increasing isothermal holding time, leading to improved coherency between the contact regions and increased interfacial strength.     

硫酸盐溶液中二癸基次膦酸的钠皂萃取Co(Ⅱ)动力学(英文)

用改进的Lewis槽研究了硫酸盐溶液中二癸基次膦酸(DDPA)的钠皂(Na-DDPA)萃取Co(II)动力学。分别考查了搅拌速度、温度、界面面积、钠皂浓度、钴离子浓度对萃取速率的影响。当搅拌速度在95~110r/min范围时,扩散阻力对萃取速率的影响可以忽略。萃取速率随着温度和比界面面积的增大而增大。计算得活化能为32.75kJ/mol。表明Na-DDPA萃取Co(II)为化学反应控制过程,Co(II)萃取的控制步骤为界面化学反应。萃取速率随着Na-DDPA和Co(II)浓度的增大而增大。得到了钴萃取动力学方程并讨论了萃取机理。     

Solvent extraction of vanadium from sulfuric acid solution

The behaviour of vanadium(V) extracted from sulfuric acid solution was investigated using Cyanex 923 as an cxtractant. The effects of the concentration of Cyanex 923 and the pH of the solution were studied. The extraction of vanadium(V) increases with the increase of Cyanex 923 concentration and shaking time. Cyanex 923 can extract vanadium(V) fi'om sulfuric acid solution at low pH conditions, and the best pH conditions for exuaction of vanadium(V) are at pH 1.0-2.0. The species extracted into the organic phase is VO2HSO4 with one molecule of Cyanex 923. Equilibrium studies were used to assess the extraction efficiency of vanadium(V) recovery from the sulfuric acid solution.     

Effects of compressive strain on the evolution of interfacial strength of steel/nickel solid-state bonding at low temperature

Solid-state bonding between ultralow-carbon steel and pure nickel was conducted by hot pressing with various compressive strain ranging from 5 to 15% and subsequent isothermal holding at 923?K. It was found that the interfacial strength of contact area is accounted for by the evolution of the intrinsic strength of the interface and the amount of plastic energy dissipation at the crack tip during interface fracture. The compression induces severe deformation around the interface and consequently inhibits the plastic energy dissipation during interface fracture. In the first stage of isothermal holding, the residual strain around the interface on the steel side is reduced by recovery process, which concurrently decreases in the yield stress of the area adjacent to the interface. This promotes plastic energy dissipation of the area, leading to a significant increase in interfacial strength in the first stage.     

Thermodynamic investigation of the solid and liquid Au---Sb alloys

The heat content of solid and liquid AuSb₂ compound was measured from 298 K to T (375–963 K) on heating (drop method) with the help of a Tian-Calvet calorimeter. The heat capacity of the liquid compound as well as its enthalpy of fusion were deduced. The enthalpy of the liquid decreases strongly when temperature increases between the melting point and 831 K.

The enthalpy of formation of the Au---Sb melts was also determined by direct reaction calorimetry at 916 K with respect to concentration. The enthalpy of mixing is weakly negative in the whole range of concentration (_min^f = −3·47 kJ/mol at x_Au = 0·775) in agreement with the results of Béja at 923 K. disagree with the much more negative earlier data of Kameda et al. and of Hino et al. by emf and vapor pressure measurements.

Finally, the liquid/Au(cr) phase boundary determined at 916 K from the break in the h^f (x_Au) curve agrees well with the phase diagram calculated by Okamoto and Massalski but not with their experimental results.     

D2EHPA—MPA—Fe^3＋协同萃取体系的动力学和界面化学研究

本文研究了协同萃取体系(D_2EHPA—MPA—Fe~(3+))的胶团形成热力学、界面特性、协萃效应和界面动力学(动力学控制机制和反应速率方程)研究发现,混合萃取体系中的D_2EHPA强烈地影响MPA的胶团形成热力学和界面吸附行为,得到了胶团生成常数(K_m)、胶团形成自由能(△G_m)和临界胶团浓度(CMC)的热力学参数D_2EHPA和MPA具有相反的界面吸附行为研究发现D_2EHPA—MPA混合萃取剂体系对Fe~(3+)产生了协萃效应动力学和界面化学的研究结果还证实了非胶束混合萃取体系的Fe~(3+)的萃取过程是受化学反应控制的,控制反应发生在界面上     

AZ31B镁合金氧化石墨烯掺杂钇盐转化膜耐蚀性研究

目的研究一种绿色环保的表面处理方法,以提高镁合金的耐蚀性。方法采用化学浸泡法,以硝酸钇为成膜物质,在AZ31B镁合金表面成功制备一种新型稀土盐转化膜,并以氧化石墨烯为阻隔剂对该转化膜进行复合掺杂。采用扫描电镜(SEM)对膜层的表面形貌进行观察,采用析氢实验和电化学测试对不同试样在3.5%Na Cl溶液中的耐蚀性进行了研究。结果镁合金钇盐转化膜表面平整均一,覆盖良好。氧化石墨烯掺杂后的钇盐膜层表面出现了大小不均一的瘤状物质,膜层完整,未出现裂痕。析氢实验结果显示,经过处理的转化膜试样可以极大地抑制腐蚀反应的发生。由极化曲线可知,钇盐转化膜的存在使镁合金的腐蚀电位发生了明显正移,正移了150 m V;而氧化石墨烯掺杂的钇盐膜层的腐蚀电位相对于掺杂前变化不大,但其腐蚀电流密度是掺杂前的1/28。电化学交流阻抗谱的测试结果显示,氧化石墨烯掺杂钇盐转化膜的电荷转移电阻最大,Rct为2485?·cm2;钇盐转化膜的电荷转移电阻次之,Rct为1224?·cm2。两者的电荷转移电阻相对于未经处理的镁合金都有明显提升。结论钇盐转化膜可以明显提高AZ31B镁合金的耐蚀性,氧化石墨烯的加入可以进一步提高转化膜层的耐蚀性。     

Thermodynamic assessment of chemical and electrochemical stability of nickel–silicon system alloys

Phase and chemical equilibria in Ni–Si system at 298 K are considered. The possible maximum solid solubility of Si in fcc-Ni at 298 K is estimated.The Ni–Si–O state diagram at 298 K is plotted. The Ni–Si–O system invariant conditions are calculated. The potential–pH diagram of the Ni–Si–H₂O system at 298 K, air pressure of 1 bar and activities of ions in solution, equal to 1 mol/l is plotted. Basic chemical and electrochemical equilibria in Ni–Si–H₂O system are considered.     

SiCP颗粒增强Al基复合材料的瞬间液相连接

采用Ni箔和Cu/Ni/Cu多层箔作中间层在923K进行了SiC颗粒增强铝基复合材料的瞬间液相连接。研究表明,无压连接时,接头强度随保温时间延长有所增高,但界面处会存在纯金属（无增强颗粒）区域和氧化物夹杂,是导致接头强度不高的主要原因。加压TLP连接则能有效改善界面组织和接头性能。采用Cu/Ni/Cu多层箔作中间层加压连接时接头强度可达189．6MPa,约为母材强度的85％。本文对压力的作用和复合材料TLP连接界面特性进行了讨论。     

高位阻β-二酮从氨性蚀刻废液中萃取铜

采用高位阻β-二酮（1-（4’十二烷基）苯基-3-叔丁基-1,3-丙二酮）作为萃取剂从模拟印刷电路板（PCBs）蚀刻废液中萃取铜。利用离子强度与萃取反应平衡常数的关系校正模拟的萃取等温线,该模拟萃取等温线与实验测得萃取等温线基本相符。通过实验确定萃取剂浓度、相比、萃取级数和反萃级数等萃取工艺参数。结果表明,在室温下对于铜离子浓度为112g/L、总氨浓度为7mol/L的模拟氨性蚀刻废液的最佳萃取条件为：萃取剂浓度为40%,相比为5：4,萃取时间为5min。在此条件下,经过一级萃取,蚀刻废液中铜离子浓度可降低至63.24g/L,能返回到电路板的生产中循环使用。用含铜30g/L,硫酸浓度180g/L的模拟废电解液对负载有机相进行反萃,相比（O/A）为1：2,经一级反萃,铜的反萃率可达98.27%。     

Characterization and growth of oxide films

Surface-analytical techniques are useful to characterize oxide films and to study growth processes on metals and semiconductors. This paper will summarize work at the National Research Council of Canada on the high temperature oxidation of nickel, chromium, FeCrAl alloys (with and without yttrium additions), β-NiAl and silicon. The application of secondary ion mass spectrometry, reflection high energy electron diffraction, and transmission electron microscopy is emphasized. Also considered is the thermal oxidation of III-V semiconductors, indium phosphide and gallium arsenide. X-ray photoelectron spectroscopy provides additional useful information on the chemical composition of the oxides. The often complementary information provided by the various techniques leads to (i) a better understanding of oxidation processes and of oxide growth mechanisms on an atomic scale, (ii) interfacial segregation phenomena, and (iii) the role of reactive elements like yttrium in modifying transport processes in oxides.     

新混合萃取剂体系的萃取动力学和胶团化作用SCIEI

本文研究了协同萃取体系(D_2EHPA-H_2RPA-Al^(3+))的胶团化作用和界面特性[H_2RPA为长碳链单烷基磷酸脂,D_2EHPA为二(2—乙基己基)磷酸],以及液—液界面动力学。结果发现,混合体系中H_2RPA具有较强烈的胶团化作用和较高的界面活性,随着[D_2EHPA]的增加,其胶团化倾向和界面活性随之下降,H_2RPA和D_2EHPA具有完全相反的界面吸附行为,证实了非胶束混合萃取体系的动力学控制机制为界面化学反应控制型,得到了反应速率方程式,非胶束体系为有应用前景的混合萃取剂体系。     

原始晶粒尺寸对ECAP变形纯钛组织性能的影响

室温下,对923 及1023 K退火1 h所得的不同原始晶粒尺寸的工业纯钛进行ECAP变形。通过TEM、EBSD、室温拉伸和显微硬度测试研究原始晶粒尺寸对ECAP变形纯钛组织性能的影响。探讨纯钛ECAP变形孪生行为和变形机制。结果表明,退火温度越高,原始晶粒尺寸越大。1道次变形后,1023 K退火纯钛的晶粒细化效果更显著。4道次变形后,923 K退火纯钛的组织更细小均匀。随着变形道次的增加,屈服强度不断增大,1道次变形后增幅最大,约为100%,且原始晶粒尺寸越大,强度增幅越大。纯钛ECAP变形机制包括位错滑移和孪生,原始晶粒尺寸越大,孪晶数量越多。     

Critical scattering of Ni–Nb–Y metallic glasses probed by quantitative anomalous small-angle X-ray scattering

Phase-separated Ni–Nb–Y metallic glasses were prepared by means of rapid quenching from the melt. Different stages of spinodal decomposition were obtained for Ni-contents between 66 and 71 at.%. From anomalous small-angle X-ray scattering experiments performed at the K-absorption edges of nickel, yttrium and niobium different correlation lengths, of between 15 and 5.5 nm, were found for the different concentrations. Moreover, from the quantitative analysis of the resonant invariant the chemical concentrations of yttrium and niobium in the random density fluctuations were deduced. The results are compared to a partially crystallized sample annealed at 773 K over 30 min.