材料期刊网

Synthesis of CDMO from LiOH and EMD and the Performances of Li/CDMO Rechargeable Batteries

Renmin LIU Guoliang WU Jiangshan LUO General Research Institute of Nonferrous Metals , Beijing , 100088 , ChinaJohn H.Kennedy Zhengming ZHANG Department of Chemistry , University of California , Santa Barbara , USAQin LIN University of Science and Technology Beijing

材料科学技术（英）

The synthesis of CDMO from LiOH and EMD has been investigated by thermogravimetry and pow- der X-ray diffraction analysis.The results showed that it took place from below 100 to 400℃.When the proportion of Li:Mn in the starting mixture was 3:7,the measured weight loss during this process was 7.40% for heat-treated EMD and 8.33% for non-heat-treated EMD.Based on these data and X-ray diffraction results the obtained product would be 3LiMn204 - MnO2.This material was es- sentially amorphous.It can insert 4.7 Li per 3LiMn_2O_4·MnO_2,leading to a capacity of 170- 200 mAh/g and demonstrated reasonable discharge and recharge cycle performance for both test cells and practical batteries.

关键词: CDMO , null

Quantum chemistry study on the effect of Cl- ion on anodic dissolution of iron in H2S-containing sulfuric acid solutions

Corrosion Science

The effect of Cl- ion on the anodic dissolution of iron in H2SO4 solutions containing low H2S level has been studied by electrochemical polarization curve measurements. The total energy and binding energy of the competitive adsorption for Cl- and HS- ions have been calculated with CNDO/2 method, as well as the net charge distribution of iron atoms at an anodic potential. The results showed that certain concentration of Cl- ion inhibit the anodic reaction of iron accelerated by HS-. However, when Cl- ion reached saturated adsorption, it began to promote the anodic reaction of iron due to the increased negative charge of iron atoms. (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词: iron;polarization;quantum chemistry;acid corrosion;anodic;dissolution;chloride solutions;kinetics

Metal-Free Heterogeneous Catalysis for Sustainable Chemistry

Chemsuschem

The current established catalytic processes used in chemical industries use metals, in many cases precious metals, or metal oxides as catalysts. These are often energy-consuming and not highly selective, wasting resources and producing greenhouse gases. Metal-free heterogeneous catalysis using carbon or carbon nitride is an interesting alternative to some current industrialized chemical processes. Carbon and carbon nitride combine environmental acceptability with inexhaustible resources and allow a favorable management of energy with good thermal conductivity Owing to lower reaction temperatures and increased selectivity, these catalysts could be candidates for green chemistry with low emission and an efficient use of the chemical feedstock This Review highlights some recent promising activities and developments in heterogeneous catalysis using only carbon and carbon nitride as catalysts The state-of-the-art and future challenges of metal-free heterogeneous catalysis are also discussed.

关键词: carbon;catalyst;heterogeneous catalysis;selectivity;sustainable;chemistry;graphitic carbon nitride;modified activated carbon;nanofiber/graphite-felt composite;ordered mesoporous carbons;oxygen;reduction reaction;nitrogen-doped graphite;fuel cell cathode;onion-like carbon;oxidative dehydrogenation;hydrogen-production

Jian ZHANG/Langhong Lou

材料科学技术（英）

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SERS and Quantum Chemistry Studies of Adsorption of Thiourea and Ethylthiourea on Silver Electrode

Acta Physico-Chimica Sinica

Adsorption of thiourea (TU) and ethylthiourea( ETU) on roughened silver electrode was investigated using in situ surf. enhanced Raman spectroscopy(SERS) Using quantum chemistry and HSAB theories, the influences of electrode potential and the different substituent groups on SERS were disc i. TU is chemisorbed perpendicularly by Ag-S bond on silver at E = -0.3 V and adsorption of TU turns into a parallel orientation at E = -0.9 V. ETU is always chemisorbed at an angle from Ag. The adsorption of ETU is through and C=C and C=O groups at E = -0.3 V, and mainly through C=C at E = -0.9V.

关键词: Surface enhanced Raman spectroscopy;Adsorption;Quantum chemistry;Thiourea;Inhibitor

LOCAL CHEMISTRY AND THE COHESIVE STRENGTH OF GRAIN BOUNDARIES IN Ni_3Al

Shanthi Subramanian , David Muller , John Silcox and Stephen L.Sass (Department of Materials Science and Engineering and Department of Applied and Engineering Physics , Cornell University , Ithaca. NY 14853)

金属学报(英文版)

Local chemistry plays an important role in determining the cohesive strength of grain boundaries in Ni3Al. Doping with B increases the room temperature ductility and changes the fracture mode from intergranular to transgranular, while doping with Zr increases the ductility but leaves the fracture mode predominantly intergranular.Electron Energy Loss Spectroscopy (EELS) and Energy Dispersive X-ray Spectroscopy (EDS) were used to probe the changes in local bonding (and hence the cohesive strength) produced by changes in local chemistry at large angle boundaries in Ni3Al.In addition , small angle tilt boundaries were studied to correlate structure with Nienrichment at the interface. B segregation to Ni-rich grain boundaries was shown to make the bonding similar to that of the bulk, thereby increasing their fracture resistance. Ni-enrichment does not occur in the presence of Zr segregation to grain boundaries. Ni-enrichment to antiphase boundaries (APB) in small angle tilt boundaries lowers the APB energy by reducing the number of high energy Al-Al interactions across the interface. Ni-enrichment to large angle boundaries is expected to produce a similar effect on energy.

关键词: : grain boundary chemistry , null , null , null

STRUCTURES OF γ Al_2O_3 AND AlON STUDIED BY ~(27)Al NMR AND QUANTUM CHEMISTRY CALCTLATIONS

X.M.Min , Y. Daiand C.W.Nan National Key Laboratory of Advanced Technology for Materials Synthesis and Processing , Wuhan University ofTechnology , Wuhan 430070 , China

金属学报(英文版)

Al NMRand quantum chemistry calculation have been used to study thestructureof γ Al2O3 and AlON. The NMRspectra arecharacterized bythree distinctresonance peaksat114 , 66 and 12 , corresponding to 〔AlN4〕,〔AlO4〕and 〔AlO6〕respectively. The uantum chemistrycalculationsshowqd thatthe models with vacancieslocated at octahedralsitein B block are morestablethanthose with vacancieslocated attetrahedralsitein A blockforboth of γ Al2 O3 and AlON. In AlON, nitrogen atoms preferentially replace oxygen atoms in〔AlO4〕tetrahedrons, and the model with 〔AlN4〕is morestablethan that with 〔AlO4 xNx〕(x= 1 ,2 and 3) and 〔AlO6 - yNy〕(y= 1 ,2 ,3 and 4) , which isin agreement with theexperimental analysisby NMR.

关键词: Al2 O3 and AlON , null , null , null

Chemistry and Process Optimization of V-Microalloyed N80-Class Seamless Casing Tube

PAN Tao , YANG Cai-fu

钢铁研究学报(英文版)

Chemistry and process optimization of N80 seamless tube was studied by thermo-mechanical simulation tester Gleeble 1500D. Several heats of V-microalloyed steel with different N contents were firstly made at lab in order to simulate N80 seamless tube steel. The results showed that N addition increased strength under condition that toughness was kept at a high level compared with low-N steel. In this study N content with 120-200 ppm enhanced combination performance of strength and toughness whether in-line normalizing process was adopted or not. In-line normalizing process was helpful to improve the toughness though it lowered strength by some degree. However, direct final rolling after tandem rolling (without in-line normalizing) helped increase strength while the toughness remained somehow poor. The above phenomena concerning N80 seamless tube was closely associated with dissolution and precipitation behavior of V(CN). V(CN) precipitation was optimized when N content was increased. When in-line normalizing process was adopted, V(CN) precipitation in austenite increased due to low temperature history during intermediate (in-line) normalizing process. V(CN) particles existing in austenite contributed to grain refinement for VN induced intergranular ferrite, while they weakened precipitation strengthening effect since V precipitating in ferrite wais reduced.

关键词: seamless tube;in-line normalizing;V-N microalloying;reheating;mechanical properties;Gleeble simulation

Surface Chemistry, Dispersion Behavior, and Slip Casting of Ti(3)AlC(2) Suspensions

Journal of the American Ceramic Society

The surface chemistry and dispersion properties of aqueous Ti(3)AlC(2) suspension were studied in terms of hydrolysis, adsorption, electrokinetic, and rheological measurements. The Ti(3)AlC(2) particle had complex surface hydroxyl groups, such as equivalent to Ti-OH,=Al-OH, and -OTi-(OH)(2), etc. The surface charging of the Ti(3)AlC(2) particle and the ion environment of suspensions were governed by these surface groups, which thus strongly influenced the stability of Ti(3)AlC(2) suspensions. PAA dispersant was added into the Ti(3)AlC(2) suspension to depress the hydrolysis of the surface groups by the adsorption protection mechanism and to increase the stability of the suspension by the steric effect. Ti(3)AlC(2) suspensions with 2.0 dwb% PAA had an excellent stability at pH=similar to 5 and presented the characteristics of Newtonian fluid. Based on the well-dispersed suspension, dense Ti(3)AlC(2) materials were obtained by slip casting and after pressureless sintering. This work provides a feasible forming method for the engineering applications of MAX-phase ceramics, wherein complex shapes, large dimensions, or controlled microstructures are needed.

关键词: liquid reaction synthesis;poly(acrylic acid);nitride;hydrolysis;stability;silica;carbide;powders;ftir

Conductivity of (NH4)3[CrMo6O24H6]·7H2O Treated by Nd Chemistry-Heated Diffused Permeation

材料科学技术（英）

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