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TEM STUDY OF C-B_4C-SiC COMPOSITES WITH SILICON ADDITIVE

ZHAO Lihua , WU Lijun , HUANG Qizhong , YANG Qiaoqin 1)(Material Research and Test Center , Hunan University , Changsha , China)2)(Powder Metallurgy Research Institute , Center-South University of Technology , Changsha , China)3)(Laboratory of Atomic Imaging of Solids , Institute of Metal Research , Chinese Academy of Science , Shenyang , China)Manuscript received 18 April 1995

金属学报(英文版)

C-B4C-SiC composites with silicon additive obtained by the hot press sintering method are studied by means of transmission electron microscopy(TEM).When the specimens are heated to 1800℃,their structure does not change.When the specimens are heated to 2000℃,carbon begins to graphitize. Moreover,two monoclinic phases are observed.One monoclinic phase named as the M phase belongs to C-center monoclinic lattice with a=0.90nm,b=0.59nm,c=0.54nm and β=119.3°.The other monoclinic phase named as the Ml phase also belongs to C-center monoclinic lattice but with a=0.85nm,b=0.49nm,c=0.53nm and β=123.6°.

关键词: :C-B_4C-SiC composite , 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

BEHAVIOUR OF α-NITROSO-β-NAPHTHOL IN HEMATITE FLOTATION

WANG Wenmei Baotou Research Institute of Rare Earth , Ministry of Metallurgy Industry , Baotou , ChinaYU Yongfu CHEN Quanyuan Changsha Institute of Mining and Metallurgy , Ministry of Metallurgy Industry , Changsha , China engineer , Baotou Research Institute of Rare Earth , Ministry of Metallurgical Industry , Baotou 014010 , China

金属学报(英文版)

Based on theoretical calculation of electronegativity of groups of flotation reagent and method of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β- naphthol in hematite flotation have been studied.The chemical adsorption seems to be predominant owing to formation of pentacyclic nitrosyl chelate compound by atoms of nitrosyl bond in α-nitroso-β-naphthol together with Fe(Ⅲ)on hematite surface.Mean- while,the nonuniform multilayer physical adsorption is also occurred.

关键词: α-nitroso-β-naphthol , null , 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

MICROSTRUCTURAL VARIATION AND FRACTURE MODES IN Al-Li ALLOYS

SONG Shihong LI Xuzhi ZHANG Weibin Central-South University of Technology , Changsha , China SONG Shihong , Department of materials Science , Central-South University of Technology , Changsha , China

金属学报(英文版)

The correlation between the diverse fracture modes and the microstructural variation with recrystallization in the Al-Li alloys under heat treatment was observed by means of triplanar optical and scanning electron microscopy.The growth,propagation and feature of their frac- tures were described from the viewpoint of microstructure,energy and geometry.

关键词: Al-Li alloy , null , null , null

SHAPE MEMORY EFFECT OF POLYCRYSTALLINE Fe-Mn-Si ALLOYS

ZHAO Qinghua TAN Shusong Central South University of Technology , Changsha , China Department of Materials , Central South University of Technology , Changsha , Hunan , China

金属学报(英文版)

The influence of quenching temperature on the shape memory effect(SME)of the Fe-Mn-Si polycrystalline alloys and their martensitic transformation temperature have been studied.The SME of the hot-rolled specimen may be remarkably enhanced by selecting quenching temperature of 600—800℃.It has been shown that SME is influenced not only by the distribution of ε-phase morphology but also by its pre-existence.

关键词: shape memory effect , null , null

MICROSTRUCTURE OF MARTENSITE IN Cu-14Al-4Ni ALLOY AGED FOR A PROLONGED TIME AT ROOM TEMPERATURE

WANG Weiguo ZHANG Yijin HUANG Jianchao Central South University of Technology , Changsha , China WANG Weiguo Lecturer , Department of Materials Science and Engineering , Central South University of Technology , Changsha , China

金属学报(英文版)

The microstrueture in shape memory alloy Cu—14Al—4Ni aged for two years at room temper- ature has been studied,and the substructure slow change has been observed.The domains of highly ordered phase and the transition regions appear at grain boundaries,the twin bounda- ries damage.Furthermore,the microstructure also gives the appearance and growth of antiphase domains like rectangular network.The long period antiphuse boundary structures and the antiphase domains have bee.observed first at the single diffracted vector .The con- centration gradient of solute atom Al has heen found from the matrixes to the grain bounda- ries,the matrixe is poor in Al and the grain boundaries are rich in Al.

关键词: shape memory alloy , null , null , null

INTERFACIAL PHENOMENA BETWEEN Al-SALT-ELECTRODE

LI Jing HUANG Kexiong WANG Zaoji LIU Jun Central South University of Technology , Changsha , ChinaGUO Chuntai Changchun Institute of Applied Chemistry , Academia Sinica , Changchun , China LI Jing Professor , Faculty of Metallurgical Physical Chemistry , Central South University of Technology , Changsha 410012 , China

金属学报(英文版)

Interfacial tension between liquid Al and molten fluoride salt was determined using sessile drop method combined with X-ray radiograph.A computer program of curve-fitting for coordination of configuration of sessile drop was used in the picture processing of the sessile drop.Regressive equation were worked out to calculate the density of the molten salt.The in- fluence of mole ratio of NaF/AlF_3,content of Li_2CO_3 and rare-earth oxides in the molten salt on interfacial tension of Al-salt was discussed.The contact angles of liquid Al on the sur- face of graphite,graphitized carbon cathode and the graphite with coating of TiB_2 were de- termined.

关键词: interfacial tension , null , null , null

Effect of Phosphates on the Metal Ion Activated Surface Complexes at the SiO_2-H_2O Interface and in Quartz Deactivation in Flotation System

SUN Zhongxi W. Forsling CHEN Jin Division of Inorganic Chemistry , Lulea University of Technology , S-951 87 Lulea , SwedenDept.of Mineral Engineering , Central South University of Technology , Changsha , 410083 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

The complexation of phosphates in the quartz-metal ion-H_2O-oleate system was studied. Computer assisted calculations with the aid of the advanced program SOLGASWATER and known equilibrium constants were used to evaluate the mechanism,The calculation results revealed that in the presence of a certain amount of phosphates, metal ions adsorbed at the quartz-H_2O interface will be transferred into solution.Thus the competi- tion for metal ions between phosphates and the quartz surface leads to surface deactivation and re- duced floatability.Various distribution diagrams clearly demonstrate the change of surface complexation as a function of added phosphate concentration.The deactivation products were also evaluated.

关键词: complexation , null , null , null , null , null

材料期刊网

TEM STUDY OF C-B_4C-SiC COMPOSITES WITH SILICON ADDITIVE

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

BEHAVIOUR OF α-NITROSO-β-NAPHTHOL IN HEMATITE FLOTATION

METASTABLE CHARACTERISTICS OF β-W

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

MICROSTRUCTURAL VARIATION AND FRACTURE MODES IN Al-Li ALLOYS

SHAPE MEMORY EFFECT OF POLYCRYSTALLINE Fe-Mn-Si ALLOYS

MICROSTRUCTURE OF MARTENSITE IN Cu-14Al-4Ni ALLOY AGED FOR A PROLONGED TIME AT ROOM TEMPERATURE

INTERFACIAL PHENOMENA BETWEEN Al-SALT-ELECTRODE

Effect of Phosphates on the Metal Ion Activated Surface Complexes at the SiO_2-H_2O Interface and in Quartz Deactivation in Flotation System

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