材料期刊网

INTERACTION BETWEEN Cu AND LIQUID Sn(II)——SEM OBSERVATION OF INTERMETALLIC GROWTH

ZHANG Qiyun , LIU Shuqi , XU Yaping Peking University , Beijing , China professor , Department of Chemistry , Peking University , Beijing , 100871 , China

金属学报(英文版)

The features of Cu_6Sn_5 growing slowly at lower temperature and growing rapidly up over 350℃,and or Cu_3Sn growing at higher temperatures,bave been detailedly observed under SEM.The increase of Pb content seems to inhibit sequentially the growth of Cu_6Sn_5 in Pb-Sn alloy.

关键词: Cu , null , null , null , null

PHASE DIAGRAM OF PrCl_3-SrCl_2-CaCl_2 SYSTEM

ZHENG Chaogui BAO Chenglin QIAO Zhiyu YE Yupu Peking University , Beijing , China 1 University of Science and Technology Beijing , Beijing , China Associate Professor , Department of Chemistry , Peking University , Beijing 100871 , China

金属学报(英文版)

Five fields corresponding to the primary crystallization of PrCl_3,Sr_3PrCl_9,α(SrCl_2, CaCl_2),α_1(CaCl_2,SrCl_2)and α_2(SrCl_2,CaCl_2)respectively,six univariant lines related to the secondary crystallization,one ternary eutectic(48.0 wt-% PrCl_3,23.5 wt-% SrCl_2; 590℃)and ternary peritectic point(45.5 wt-% PrCl_3,24.5 wt-% SrCl_2;614℃) were determined by DTA.Attempts were also made to explore the rule governing the alteration in the phase diagram containing rare earth chloride,formation of compound and its stability by means of polarization and counter-polarization.

关键词: PrCl_3 , null , null , null

INTERFACIAL ACTIVITY BEHEAVIOR OF FLUX DURING ALUMINIUM BRAZING

ZHANG Qiyun LIU Shuqi LAN Tie FU Yuchuan Peking University , Beijing , China ZHANG Qiyun , Professor , Department of Chemistry , Peking University , Beijing , China

金属学报(英文版)

A study on the interfacial activity behavior of flux during aluminium brazing has been made by using metallography,SEM and electron prob techniques.The results show that the activity, of a flux is caused by the wetting of base metal with the liquid heavy metal reduced from the flux,thus,some regions of liquid alloy created,at which no aluminium oxide film covers on the surfaces.The reduced metal drops are finally trapped in the fillet.The size of the metal drops increases with the decrease of brazing temperature.

关键词: aluminium brazing , null , null

FREE ENERGIES OF FORMATION FOR ELECTROCHEMICALLOY ALLOYED Y-Cu SYSTEM

YANG Qiqin LIU Guankun LIU Zejin Zhongshan University , Guangzhou , China YANG Qiqin , Associate Professor , Department of Chemistry , Zhongshan University , Guangzhou , China

金属学报(英文版)

The electrochemical alloying of Y-Cu system in molten NaCl-KCl-YCl_3 has been investi- gated.The free energy changes of the formation reactions of the intermetallic compounds,in- cluding YCu_6 ,YCu_4 YCu_2 ,Yfu(973—103 K),were determined by means of electrode potential-time curves of the working electrode after potentiostatic electrolysis.The results in- dicate that the potential-time method is simple and reliable.

关键词: Y-Cu system , null , null

EFFECT OF OXYGEN CONTENTS ON OXYGEN POTENTIALS OF H_2O-H_2 AND H_2O-H_2-INERTS GAS MIXTURES

FANG Zheng CHEN Xinmin(H.M.Chen) Central South University of Technology , Changsha , China FANG Zheng , Associate Professor , Department of Chemistry , Central South University of Technology , Changsha , China

金属学报(英文版)

By taking the effect of oxygen contents into account,a new set of formulae which represents the oxygen potentials of H_2O-H_2 and H_2O-H_2-inerts gas mixtures has been derived.Classi- cal representation is only a particular case of it.Some of the variables affecting equilibrium atmosphere when trace oxygen is present and optimum preparation of the gas mixtures to min- imize errors have been discussed.The reliability of some of previous equilibrium experiments under the oxygen potentials controlled by H_2O-H_2 or H_2O-H_2-inerts gas mixtures has also been criticized.

关键词: gas equilibration method , null , null , null

METASTABLE CHARACTERISTICS OF β-W

HUANG Huimin CHEN Xinmin Central South University of Technology , Changsha , China HUANG Huimin Associate Professor , Department of Chemistry , Central South University of Technology , Changsha , China

金属学报(英文版)

The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.

关键词: tungsten , null , null , null

LOCAL EQUILIBRIUM METHOD IN STUDYING PHASE DIAGRAM OF Mn-MnO SYSTEM

CHEN Qiyuan Central South University of Technology , Changsha , China CHEN Qiyuan Associate Professor , Department of Chemistry , Central South University of Technology , Changsha , China

金属学报(英文版)

A special method based on the local equilibrium principle has been introduced in the research of the phase diagram of Mn-MnO system.With this method,the problems of volatilization of Mn and the corrosion of Mn and MnO to refractory materials were prevented efficiently.The solubility of oxygen in Mn and the composition of the interface between MnO and Mn were determined.Partial phase diagram of Mn-MnO system were constructed according to pres- ent experimental results.

关键词: local equilibrium method , null , null

PHASE DIAGRAMS OF SYSTEMS SmCl_3-CaCl_2 AND SmCl_3-LiCl

ZHANG Yifeng MENG Bo GU Yunyan Northeast University of Technology , Shenyang , China Professor , Department of Chemistry , Northeast University of Technology , Shenyang 110006 , China

金属学报(英文版)

The phase diagrams of binary systems SmCl_3-CaCl_2 and SmCl_3-LiCl were determined by DTA and X-ray diffraction analysis.The system SmCl_3-CaCl_2 is of a simple eutectic type with eutectic point of 55.8mol-% SmCl_3 at 545℃.The system SmCl_3-LiCl is of the type with incongruent melting phase 2SmCl_3·LiCl at peritectic point 434℃ and with eutectic point of 31.5 mol-% SmCl_3 at 395℃.

关键词: SmCl_3-CaCl_2 , null , null

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

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