Thermodynamic calculation of Sn(IV)-NH~(4 )-Cl~--H_2O system

1　INTRODUCTIONAntimonydopedtinoxide ,forshortATO ,withexcellentconductivityperformance ,isakindofmetaloxide powders .Duetoitswideapplication ,thepreparationandapplicationareabroadintheworld .Atpresent ,tincompoundssuchasSnCl4 ·5H2 O ,SnO2 andSn(OH) 4areusuallyusedtoprepareATOpowders[18] .Allthesestanniccompoundsarepre paredbypure ,expensivetin ;furthermore ,SnCl4 isveryeasytovolatilize ,whichcauseshardmeasure ment ;inaddition ,usingSnO2 orSnO2 ·2H2 Otopre pareATOdemandforrigo…     

Interdiffusion study on Co(W) solid solution and topological close-packed μ phase in Co–W system

An interdiffusion study is conducted on the Co–W system by a diffusion couple technique. The interdiffusion coefficient of the Co(W) solid solution and the Co₇W₆ μ phase is determined. The activation energy is found to increase with the W content of the Co(W) solid solution.     

Experimental thermodynamic study of intermetallic phases in the binary Ag–Te system by an improved EMF method

A thermodynamic study of the solid two-phase regions of the binary Ag–Te system was made by an improved EMF method, using fast ion conductor RbAg₄I₅ as the solid electrolyte. The EMF measurements were made on three galvanic cells: [Ag | RbAg₄I₅ | Ag₅Te₃ + Te], [Ag | RbAg₄I₅ | Ag₅Te₃ + Ag_1.9Te] and [Ag | RbAg₄I₅ | Ag_1.9Te + Ag₂Te].Based on the results obtained, the EMF for each equilibrium phase assembly was expressed as a function of temperature, in the different regions of thermal stability of the substances. By using the observed EMF and temperature relations, the thermodynamic functions of the stoichiometric equilibrium phase assemblages: Ag₅Te₃–Te, Ag₅Te₃–Ag_1.9Te, Ag₅Te₃–Ag₂Te and Ag₂Te–Ag_1.9Te, in the low-temperature range 22–204 °C, as well as phase transformation temperatures, have been determined. Agreement between the results obtained and the literature values were established.     

Stability of supersaturated solid solution of quenched Al–X(X 5 Zn,Mg, Cu) binary alloys

In this study, the changing trend of crystal-lattice constant and the influential factors of the stability of supersaturated solid solutions with various alloying additions in the Al–X(Zn, Mg, Cu) binary alloys were investigated. The samples were analyzed using X-ray diffraction(XRD),X-ray absorption fine structure(XAFS), and scanning electron microscope(SEM). It is found that the addition of Cu causes the largest change of crystal-lattice constant of the Al–xCu supersaturated solid solution binary alloy. The most dramatic change occurs in the initial stage of Cu addition.The change is stabilized thereafter. Also, at the same alloying element addition to the Al–X(X = Zn, Mg, Cu)binary alloys, the Al–xCu is the most unstable system.Influential factors of the stability include the lattice constant change and the type of alloying element. The larger the lattice constant changes, the more unstable the supersaturated solid solution is. The alloying element, easy to aggregate, often leads to the solid solution less stable.     

α-Ni(OH)2 electrodeposition from NiCl2 solution

α-Ni(OH)₂ was synthesized from a NiCl₂ solution by electrodeposition method. In order to conduct a systematic study on the effects of experimental parameters, a series of electrolyte initial pH values, current densities, electrodeposition temperatures, and electrodeposition time were used. Cyclic voltammetry results demonstrated a side reaction of Ni²⁺+2e→Ni. The X-ray diffraction analysis, Fourier-transform infrared spectrum, and the color of the product showed that pure α-Ni(OH)₂ could be obtained in the initial pH value range of 2–5.86, current density range of 10–25 mA/cm² electrodeposition temperature range of 25–35 °C, and electrodeposition time range of 1.0–3.0 h. When electrodeposition temperature increased to 45 °C, a mixture of α-Ni(OH)₂ and metallic Ni was obtained. A current density higher than 30 mA/cm² resulted in the sample with features of β-Ni(OH)₂. A small amount of metallic Ni existed in the as-prepared sample when current density decreased to 5 mA/cm². A slight increase of electrolyte pH was observed with increasing initial solution pH and current density. Electrodeposition mass revealed a slight decrease with initial pH decreasing and showed an almost linear increase with current density increasing. The slope of the curve for electrodeposition mass versus electrodeposition time remained stable in the first 2.0 h and then decreased.     

Kinetics of oxidation-precipitation of cobalt(Ⅱ) from solution by ozone

In order to precipitate cobalt(II) in cobalt chloride solution, a novel method using ozone as the precipitant for its strong oxidability was proposed. The results show that the precipitation reaction is diffusion-controlled. The main factors affecting the oxidation rate such as the stirring speed, solution temperature, ozone partial pressure, initial concentration and flow rate were investigated. The kinetics equation of each condition was established. The results indicate that the oxidation rate is independent of the initial concentration or solution temperature. The oxidation rate increases obviously with increasing the stirring speed. The linear relationship between ozone partial pressure or flow rate and oxidation rate is found.     

Magnetic properties of Nd_2Fe_(14)B/α-Fe nanocomposite magnets with yttrium addition

The phase evolution and magnetic properties of Nd9?xYxFe72Ti2Zr2B15 (x = 0,0.5,1,and 2) melt-spun nanocomposite ribbons were studied.It is found that Y addition not only enhances the formability of amorphous phase in the alloy,but also stabilizes the amorphous phase during the annealing treatment.The appropriate content of Y addition effectively enhances the remanence (Jr) of the annealed sample.The residual amorphous intergranular phase in the annealed sample optimizes the squareness of the loop,resulting in an larger maximum energy product (BH)max.The best magnetic properties,Jr = 0.78 T,Hci (coercivity) = 923.4 kA/m,and (BH)max = 98.5 kJ/m3,were obtained from the Nd8YFe72Ti2Zr2B15 ribbon spun at Vs = 4 m/s and annealed at 700°C for 10 min,which is composed of Nd2Fe14B,α-Fe,and amorphous phase.     

Existing form of Mo(Ⅵ) in acidic sulfate solution

The existing form of molybdenum in acidic sulfate solution was studied by means of ion exchange,infrared(IR) spectra and X-ray photoelectron spectroscopy(XPS).The results indicate that the anionic molybdenum species are predominant in acidic sulfate solution,and Mo(VI) can combine with sulfate radical to form heteropoly acid anions[Mo_2O_5(SO_4)_2]~(2-) and[MoO_2(HSO_4)_4]~(2-).With the decrease in solution pH from 1.92 to 0.06,the existing form of Mo(VI) changes from Mo_7O_(21)(OH)_3~(3-) to[Mo_2O_5(SO_4)_2]~(2-) and then becomes[MoO_2(HSO_4)_4]~(2-),which results in the decrease in the resin adsorption capacity for molybdenum.     

A black electrodeposited copper–tin (Cu–Sn) alloy film for solar thermal absorbers

This study was aimed at identifying the organic molecules oxidising the Cu–Sn alloy coating in a sulphate electroplating bath to form a black solar absorbing surface. For this purpose, 20 organic chemicals were used separately in the electroplating bath to obtain Cu–Sn alloy thin films. The films were characterised using the spectroscopic methods. It was found that addition of EDTP (N, N-dimethyl-dithiocarbamylpropyl sulphonic acid, sodium salt) provided the best optical parameters.     

SrFe_(12)O_(19)/α-Fe纳米复合双层膜的微磁学模拟

采用微磁学模拟软件OOMMF详细研究了软磁相厚度对SrFe_(12)O_(19)/α-Fe纳米复合双层膜体系磁性能的影响。结果显示,固定硬磁相厚度10nm,随着软磁相厚度(Ls)的增加,体系由完全耦合的单相反转行为转变为软磁相部分优先形核的两相反转行为,并表现出显著的剩磁增强效应,矫顽力逐渐降低;最大磁能积随着软磁相厚度的增加,先增大后减小,并在Ls=5nm时取得峰值,达到165.57kJ/m~3,远远超过目前单相高性能铁氧体的最大磁能积40kJ/m~3。     

The microstructural evolution of Ti2SnC from Sn–Ti–C system by Self-propagating high-temperature synthesis (SHS)

A mechanism of Ti₂SnC from Sn–Ti–C powder mixture was investigated by the observation of the microstructural evolution in a quenched sample prepared using a combustion front self-extinguished method. Microstructural evolution in the quenched sample was observed using the scanning electron microscopy (SEM) equipped with energy-dispersive spectrum (EDS), and the phase constituents of the different zones of the sample were inspected by X-ray diffraction (XRD). The result shows that, In the Ti–Sn–C system, Ti₆Sn₅ and TiC compounds were firstly formed, between Ti, Sn and C, and then Ti₆Sn₅ compounds reacted with TiC to form Ti₂SnC, at last Ti₂SnC began to decompose partly.     

Isothermal section (500 ℃) of phase diagram of Nd-Al-Si ternary system

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＡｌ Ｓｉｅｑｕｉｌｉｂｒｉｕｍ ｐｈａｓｅｄｉａｇｒａｍｈａｓｂｅｅｎｓｔｕｄｉｅｄｂｙｍａｎｙｒｅｓｅａｒｃｈｅｒｓ[1～5] .ＮｏｉｎｔｅｒｍｅｔａｌｌｉｃｃｏｍｐｏｕｎｄｗａｓｄｉｓｃｏｖｅｒｅｄｉｎＡｌ Ｓｉｂｉｎａｒｙｓｙｓｔｅｍ .ＴｈｅｓｏｌｕｂｉｌｉｔｙｏｆＳｉｉｎＡｌｉｓ0 .80 % ( 0 .77% ,ｍｏｌｅｆｒａｃｔｉｏｎ) ,ＡｌｉｓｉｎｓｏｌｕｂｌｅｉｎＳｉａｔ 50 0℃[1 ] .Ｈｏｗｅｖ ｅｒ ,Ｅｌｌｉｏｔｔ[2 ] ｒｅｐｏｒｔｅｄｔｈａｔｔｈｅｓｏｌｕｂｉｌｉｔｙｏ…     

(Short communication) Degradation of corrosion resistance of Zircaloy-4 in LiOH aqueous solution

To investigate the degradation of corrosion resistance of Zircaloy-4 in LiOH aqueous solution, SIMS (secondary ion mass spectrometry) analysis was performed to examine the profiles of Li~ , K~ , and OH~- in oxide layers formed in the same concentration (0.1 mol/L) LiOH and KOH solutions. Even though the oxide layers have an equal thickness, the penetration depth of K~ is shallower than that of Li~ , and the penetration depth of OH~- corroded in KOH solution is also shallower than that corroded in LiOH solution. It shows that the diffusion of OH~- into oxide layer is accompanied by the corresponding cation. The difference of degradation effect of LiOH and KOH solutions on the corrosion resistance of Zircaloy-4 was discussed.     

Thermodynamic analysis of β → α(α_2) phase transformation temperature in a Ti-Al-H alloy system

The T0 face equation of a Ti-Al-H alloy system was set up by the regular solution model,and the relationship between the β phase stabilizing parameter of hydrogen and the equilibrium phase compositions was attained.According to the T0 face equation and the thermodynamic parameters from literature,the effect of hydrogen on the β→α(α2) transformation temperature was evaluated.The calculated results were in a better consistence with the measured ones.     

TiC(100)/α-Fe(100)界面稳定性及电子特性的第一性原理研究

采用第一性原理方法,研究了 TiC(100)/Fe(100)界面稳定性和电子特性.建立了 4种不同原子堆垛方式的界面模型,采用界面粘附功、界面能和断裂功评价界面稳定性;采用差分电荷密度、Mulliken布居和态密度分析了电子特性.结果表明:Fe原子位于C原子上方的堆垛模型界面粘附功最大,界面能最小,界面结构最稳定.其界...     

Hot corrosion of Ti–46Al–8Ta (at.%) intermetallic alloy

Hot corrosion behaviour of a fully lamellar Ti–46Al–8Ta (at.%) alloy was studied in air under thermal cycling conditions (20-h cycles) at 700 and 800 °C. The samples were purposely contaminated with salt deposits consisting of NaCl or Na₂SO₄ or a mixture of these. The progress of degradation was followed by mass change measurements and visual inspection. Post-exposure examination involved scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The composition of salt deposits clearly influenced the rate and type of corrosion. Sodium chloride appeared especially harmful because of the formation of volatile chloride species.     

Synthesis of antimony tris(mercaptoethyl carboxylates) as thermal stabilizer for polyvinyl chloride

A novel type of thermal stabilizers-antimony tris(mercaptoethyl carboxylates) (Sb(SCH2CH2OOCR) 3), was synthesized from carboxylic acid, antimony trioxide and 2-mercaptoethanol in two steps. The experimental results show that the molar ratio of carboxylic acid to antimony tris(2-hydroxyethyl mercaptide) is 1.2, when adding 0.6% tetra-n-butyl titanate as catalyst and xylene as isotropic solvent, heating and refluxing for about 2～4h. The thermal stability was measured by heat-aging oven test. The thermal stability time is about 8～40min(at 200℃) when adding 2% tetra-n-butyl titanate in polyvinyl chloride(PVC). Among these stabilizers, antimony tris(mercaptoethyl stearate) has best thermal stability. Its thermal stability is better than that of Ca-Zn complex and basic lead stabilizers, and equal to that of organotin. In addition, the stabilization mechanism of this kind of stabilizers for PVC was discussed briefly.     

Direct production of porous cathode material (La1−x Sr x MnO3) using a reactive DC thermal plasma spray system

The cathode material (La_0.8Sr_0.2MnO₃) in solid oxide fuel cells (SOFCs) was plasma sprayed on mild steel in a reactive DC thermal plasma spray process. This high-speed process of depositing thin films for the components of SOFCs was examined experimentally. The results showed that a coating layer of La_0.8Sr_0.2MnO₃ with a particular porosity could be obtained directly using both prereacted La_0.8Sr_0.2MnO₃ and mixed raw materials (La₂O₃, SrCO₃, and MnO or MnCO₃) as feed materials with or without a pore former. The heat treatment of the plasma coating material at 1073 K (800 °C) for 3 h significantly enhanced the desired crystallization of La_0.8Sr_0.2MnO₃ in the coated material.