材料期刊网

ACTIVITIES OF COMPONENTS IN MgO-B_2O_3 MELT

ZHANG Chengtao JI Chunlin Northeast University of Technology , Shenyang , China ZHANG Chengtao , Division of Physical Chemistry of Metallurgy , Northeast University of Technology , Shenyang , China

金属学报(英文版)

The activity of MgO in MgO-B2O_3 melt was experimentally determined at 1773 and 1823 K by means of slag-liquid Sn equilibrium.The activity of B_2O_3 was calculated by integrating Gibbs-Duhem equation.The standard Gibbs energies of formation of binary compounds 2MgOB_2O_3 and 3MgO·B_2O_3 were estimated with the activity data of components in B_2O_3-MgO melt.

关键词: MgO-B_2O_3 , null , null

A New Physical Metallurgy Phenomenon-the Shock Wave Nanocrystallization of Amorphous Alloys

材料科学技术（英文）

关键词:

Application of Microwave Radiation to Extractive Metallurgy

LIU Chunpeng XU Yousheng HUA Yixin Kunming Institute of Technology , Kunming , 650093 , China.

材料科学技术（英文）

In applying the microwave radiation to extractive me- tallurgy,it is essential first of all to find the extent of microwave energy absorbed by various minerals experi- mentally.In this paper,more than 25 kinds of common useful minerals have been individually irradiated by a 500 W,2450 MHz microwave source in an enclosed quartz crucible to ascertain their heating temperature in a definite time.In addition,the reduction and cbloridization tests were also carried out on the titanomagnetite concentrate and pentlandite with microwave heating,respectively. These experiments indicate potential applications of util- izing microwave energy in extractive metallurgy.

关键词: microwave radiation , null , null , null

OXIDE METALLURGY-ITS PURPOSES AND PRACTICAL APPROACHES

Z. T. Ma and D. Janke(Institute of Iron and Steel Technology , Freiberg University of Mining and Technology , Germany)

金属学报(英文版)

Useder certain conditions, nonmctallic inclusions such as oxides, sulfides, nitrides and carbides are no longer harmful to sted service properties. With the new concept of oxide metallurgy, these properties can be improved by generating fine oxide inclusions which serve as heterogeneous nuclei for sulfide and fine ferrite[1-4]. A novel continuous casting (CC) process is expected to be created with the utilization of oxide metallurgy. This is also useful for the forthcoming technologies of direct rolling and near-net-shape casting. The main idea of oxide metallurgy consists of an alternative oxidation technology. It is based on steels treated by complex metals such as Ti, Zr, Ti-Zr alloys and rare earth metals. The selected deoxidants should follow the required conditions which are concluded in this paper.

关键词: oxide , null , 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

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

MEASUREMENT AND APPLICATION OF PHYSICAL PARAMETERS IN UNSTEADY HEAT CONDUCTION

S. X. Wanng , D. S. Zheng , Y. L. Liu 1) Department of Material Engineering , Luoyang Institute of Technology , Luoyang 471039 , China 2) Luoyang Copper (Group) Co. , Ltd , Luoyang , China

金属学报(英文版)

As far as the accuracy of calculating unsteady temperature field is concerned, it is very important to find the accurate physical parameters such as specific heat, thermal conductivity, latent heat of phase transformation and surface heat flux. The model for calculating H and Q is established in this paper. The measurement methods and data processing for physical parameters such as volume specific heat C, thermal conductivity k, volume latent heat of phase transformation c1 and surface heat flux are introduced The physical parameters of 1Cr18Ni9Ti and 45 steels and the surface heat flux for 1 Cr18Ni9Ti probe cooled in water,10% NaCl water and oil with different temperatures are measured, respectively. These data show that the probability of absolute error less than 2* C between the calculated and measured values in temperature field calculation reaches above 80% if using the above physical parameters, which provides a reliable technology basis for precise calculation of temperature field.

关键词: unsteady temperature field , null

Improvement of Ductility of Powder Metallurgy Titanium Alloys by Addition of Rare Earth Element

Yong LIU , Lifang CHEN , Weifeng WEI , Huiping TANG , Bin LIU

材料科学技术（英文）

Ti-4.5Al-6.0Mo-1.5Fe, Ti-6Al-1Mo-1Fe and Ti-6Al-4V alloys were prepared by blended elemental powder metallurgy (PM) process, and the effects of Nd on the microstructures and mechanical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found out that the addition of Nd increased the density of sintered titanium alloys slightly by a maximum increment of 1% because small amount of liquid phase occurred during sintering. The addition of Nd shows little effect on the improvement of tensile strength, while the elongation is significantly improved. For example, the elongation of Ti-4.5Al-6.0Mo-1.5Fe can be increased from 1% without addition of Nd to 13% at a Nd content of 1.2 wt pct.

关键词: Powder metallurgy titanium alloy , null , null , null

APPLICATIONS OF PHYSICAL SIMULATION IN THE DEVELOPMENT OF HOT WORKING PROCESSES

L. P. Karjalainen (Department of Mechanical Engineering , University of Oulu , Oulu , Finland)

金属学报(英文版)

Modelling has become a more and more valuable tool in the design, control and development of steel processing. Empirical regression equations, physically based approachs, artificial neural networks and hybrid models are being theied in computer modelling. In all cases, relevant data are necessary, which can be most economically obtained by physical simulation. Physical simulation with a Gleeble simulator has been used in a large number of tasks at the University of Oulu for ten years in cooperotion with the Finnish metals industry. Some examples of these will be described and discussed below, such as the optimization of the recrystallization controlled rolling process, the improvement of the hot strength model for the control of coiling tension and the optimization of continuous strip annealing schedules.Finally,brief remarks will be then on a couple of projects now under way.

关键词: physical simulation , null , null , null , null