材料期刊网

MICROSTRUCTURE AND FATIGUE PROPERTIES OF RAIL STEEL

ZHOU Qingyue ZHO U Chenguang China Academy of Railway Sciences , Beijing , China Engineer , Metal and Chemistry Research Institute , China Academy of Railway Sciences , Beijing 100081 , China

金属学报(英文版)

The subcritical propagation of fatigue cracks and the microstructure of rail steel with relation to stress ratio have been studied.The effect of mierostrueture of the rail steel on their fatigue lives has been discussed.

关键词: rail steel , 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

MICROSTRUCTURE AND PROPERTIES OF SiC_w/6061Al COMPOSITE The Author is now with Institute of Metal Research,Academia Sinica,China

MA Zongyi YAO Zhongkai Harbin Institute of Technology , Harbin , China

金属学报(英文版)

The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure

关键词: composite , null , null , null

Luoyang Institute of Refractories Research Ministry of Metallurgical Industry

ZHONG Xiangchong Luoyang Institute of Refractories Research , Luoyang , China.

材料科学技术（英文）

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Mechanical and Galvano-chemistry Property Variation within Dissimilar Metal Weld between 1Cr18Ni9Ti and 1Cr13 Stainless Steel

Yongtao Zhao Junhui Dong Yonglin Ma Liping Zhao Xiaobing Pei

材料科学技术（英文）

The purpose of this study is to discuss the microstructure and properties variation of the weld metal in the dissimilar stainless steels during the argon tungsten-arc welding process. Because of the existence of different materials and chemistry variation within welds, properties, such as tensile and fracture properties and so on, are expected to show spatial variation. In the study, microstructures were observed by optical and electron microscopy. Good appearance and uniform structure and typical dendrite structure were observed in welding joint. The micro-hardness tester and electronic universal stretcher were used to measure the mechanical properties of the weldments and base metals. The heat affected zone (HAZ) near 1Cr13 hardness is up to peak value of 1150 HV, the strength of weldments is nearly same as austenite stainless steel. In addition,
through seawater immersion test, polarization curves and AC impedance spectroscopy of the weldments and base metals are obtained. It was found that corrosion resistance at welding joint lies between 1C13 and 1Cr18Ni9Ti.

关键词: 1Cr13 , 1Cr18Ni9Ti , welding joint , mechanical and galvano－chemistry

Metal Dusting-Mechanisms and Preventions

J.Q.ZHANGD.J.YOUNG

中国腐蚀与防护学报

Metaldusting attacks iron, low and high alloy steels and nickel-or cobalt-base alloys by disintegrating bulk metals and alloys into metal particles in a coke deposit. It occurs in strongly carburising gas atmospheres (carbon activity a_C>1) at elevated temperatures (400 ℃~1000 ℃). This phenomenon has been studied for decades, but the detailed mechanism is still not well understood. Current methods of protection against metal dusting are either directed to the process conditions-temperature and gas composition-or to the development of a dense adherent oxide layer on the surface of the alloy by selective oxidation. However, metal dusting still occurs by carbon dissolving in the base metal via defects in the oxide scale. The research work at UNSW is aimed at determining the detailed mechanism of metal dusting of both ferritic and austenitic alloys, in particular the microprocesses of graphite deposition, nanoparticle formation and underlying metal destruction. This work was carried out using surface observation, cross-section analysis by focused ion beam and electron microscopic examination of coke deposits at different stages of the reaction. It was found that surface orientation affected carbon deposition and metal dusting at the initial stage of the reaction. Metal dusting occurred only when graphite grew into the metal interior where the volume expansion is responsible for metal disintegration and dusting. It was also found that the metal dusting process could be significantly changed by alterations in alloy chemistry. Germanium was found to affect the iron dusting process by destabilising Fe₃C but increasing the rate of carbon deposition and dusting, which questions the role of cementite in ferritic alloy dusting. Whilst adding copper to iron did not change the carburisation kinetics, cementite formation and coke morphology, copper alloying reduced nickel and nickel-base alloy dusting rates significantly. Application of these fundamental results to the dusting behaviour of engineering alloys is discussed.

关键词: metal dusting , null , null , null , null , null

Discovery and Research of High Tc Superconductor in the Institute of Physics, Academia Sinica

CHEN Liquan A special member of CCAST (World Laboratory) , Post Address: Institute of Physics , Academia Sinica , P.O. Box. 603. Beijing , China.

材料科学技术（英文）

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Technical note: Research and development of localized corrosion rate monitoring instrument for nonpassivable metal in corrosive media

Corrosion

This paper introduces the design of a localized corrosion rate monitoring instrument that can monitor and evaluate the maximum and stable localized corrosion rate of a nonpassivable metal in a corrosive environment by measuring the current density in a corrosion sensor with an occluded anode.

关键词: instrument;localized corrosion rate;monitor

Characteristics and Nature of Metal Fog in Molten Salts

QIU Zhuxian FAN Liman K.Grjotheim H.Kvande Northeast University of Technology , Shenyang , 110006 , China.University of Oslo , Norway.

材料科学技术（英文）

In this paper are reported the characteristics and nature of metal fog in molten cryolite-alumina mixtures on the basis of laboratory experiments and quantum chemistry studies.The metal fog is the finely divided metal particles in the molten salts, and it dissolves partly in the molten cryolite to form atomic clusters,such as(Al_nNa_m)~(x+) type.

关键词: metal fog , null , null

Research on Metal Hydride Compressor System

稀有金属（英文版）

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