材料期刊网

LIFE PREDICTION OF HIGH TEMPERATURE STRUCTURALCOMPONENT BY STRAIN RANGE PARTITIONING

Author M. Miyahara1) and K. Tokimasa2) 1) Corporate Research & Development Laboratories , Sumitomo Metal Industries , Ltd. , Amagasaki , Japan2) Department of Mechanical Engineering , School of BiologyOriented Science and Technology , Kinki University , Uchitacho , Wakayama , JapanManuscript received 18 October 1998

金属学报(英文版)

The authors recent works on the improvement of the Strain Range Partitioning(SRP) method and its application to the life prediction of high temperature structural components are summarized. Examined components are divided into three groups, that is, components in the steel production plants, in the automobile and in the fossil power plants. Based on the results of the inelastic analysis and the creepfatigue properties of the material, which were obtained by IJ(=PP,PC, CP, CC) tests, the effects of the material properties, operating conditions and configuration of components were quantitatively evaluated to select the most effective measures for the thermal fatigue life extension. The SRP has been successfully applied until now to the life prediction and extension of the actual structural components subjected to thermal cycling by the authors.

关键词: creepfatigue , null , null , null

THE REMAINING LIFE EVALUATION BASED ON THESTRAIN RANGE PARTITIONING APPROACH

Author K. Tokimasa1) and M. Miyahara2) 1) Department of Mechanical Engineering , School of BiologyOriented Science and Technology , Kinki University , Uchitacho , Wakayama , Japan2) Corporate Research & Development Laboratories , Sumitomo Metal Industries , Ltd. , Amagasaki , JapanManuscript received 18 October 1998

金属学报(英文版)

The two procedures based on the strain range partitioning approach are proposed for evaluating the remaining life by measuring the surface crack length. Both the procedures require that the material parameters describing the creepfatigue damage rule built and modified by the authors and the strain waveform applied have been clarified before the evaluation. One of the procedures can be used only when the total number of the operation cycles n are known, whereas the other is useful even when n is unknown, though it needs the additional crack length measurement. In the latter the surface crack length must be measured not only at n but also at n+n, where n is a given interval of cycles. The results of their application to Mod.9Cr1Mo and 316LC steel smooth specimens subjected to the IJ type creepfatigue loading are shown.

关键词: creepfatigue , null , 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

Study on Process Parameters Optimization of Sheet Metal Forming Based on PFEA/ANN/GA

Juhua HUANG , Jinjun RAO , Xuefeng LI

材料科学技术（英）

Sheet metal forming is widely applied to automobile, aviation, space flight, ship, instrument, and appliance industries. In this paper, based on analyzing the shortcoming of general finite element analysis (FEA), the conception of parametric finite element analysis (PFEA) is presented. The parametric finite element analysis, artificial neural networks (ANN) and genetic algorithm (GA) are combined to research thoroughly on the problems of process parameters optimization of sheet metal forming. The author programs the optimization scheme and applies it in a research of optimization problem of inside square hole flanging technological parameters. The optimization result coincides well with the result of experiment. The research shows that the optimization scheme offers a good new way in die design and sheet metal forming field.

关键词: Sheet metal forming , null , null , null

Mysterious Waters at Metal Surfaces

材料科学技术（英）

Molecular structures of adsorbed waters at metal surfaces are essential to understanding the widespread processes ranging from ice nucleation, to water involved catalytic surface reactions, to many phenomena of biological and astrochemical importance. Instead of providing a comprehensive literature survey, we focus in this review on detailed structural information, such as water orientations and occupation sites, of intact waters at low temperatures and ultrahigh vacuum conditions investigated by various surface techniques. Despite progresses made in direct imaging the surface waters at high resolutions, as exemplified in a close-packed (e.g. Pd(111)) and an open metal surfaces (e.g. Cu(110)) supported waters, structural mysteries remain at diverse metal surfaces. We highlight experimental challenges and discuss structural mysteries in elucidating surface water structures at molecular levels.

关键词: Water monolayer;Surface structure;Transition metal surfaces;scanning-tunneling-microscopy;density-functional theory;vibrational-spectra;ice;pt(111);adsorption;dissociation;ru(0001);excitation;molecules

Mysterious Waters at Metal Surfaces

Jibiao Li Shenglong Zhu Fuhui Wang

材料科学技术（英）

Molecular structures of adsorbed waters at metal surfaces are essential to understanding the widespread processes ranging from ice nucleation, to water involved catalytic surface reactions, to many phenomena of biological and astrochemical importance. Instead of providing a comprehensive literature survey, we focus in this review on detailed structural information, such as water orientations and occupation sites, of intact waters at low temperatures and ultrahigh vacuum conditions investigated by various surface techniques. Despite progresses made in direct imaging the surface waters at high resolutions, as exemplified in a close-packed (e.g. Pd(111)) and an open metal surfaces (e.g. Cu(110)) supported waters, structural mysteries remain at diverse metal surfaces. We highlight experimental challenges and discuss structural mysteries in elucidating surface
water structures at molecular levels.

关键词: Water monolayer , surface structure , transition metal surfaces

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

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）

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

EFFECTS OF METAL IONS ON THE CONFORMATIONAL CHANGES OF DNA

G.Q. Liu , Y.Y. Meng , S.H. Liu , Y.H. Hu

金属学报(英文版)

DNA takes on multi-different conformations such as A-, B-, C-, D- and Z-form. These conformations can transit to one another when DNA deposited in some metal ions solutions or when changing the concentrations of the same metal ions. Here, several major conformational transitions of DNA induced by metal ions under different environment were introduced and the mechanism of the interaction of metal ions with DNA was discuss in detail.

关键词: DNA , null , null

Metal Oxide Nanostructures from Simple Metal-oxygen Reaction in Air

Ting YU , Zexaing SHEN

材料科学技术（英）

Metal oxide nanostructures (CuO, Co3O4, ZnO and α-Fe2O3) have been successfully fabricated by a simple and efficient method: heating the appropriate metals in air at low temperatures ranging from 200 to 400℃. The chemical composition, morphology and crystallinity of the nanostructures have been characterized by micro-Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Two mechanisms: vapor-solid and surface diffusion play dominant roles in the growth of metal oxide nanostructures starting with low melting point metals (Zn and Cu) and high melting point metals (Fe and Co), respectively. With sharp ends and large aspect ratio, the metal oxide nanostructures exhibit impressive field-induced electron emission properties, indicating their potentials as future electron source and displays. The water wettability and anti-wettability properties of iron oxide nanoflakes were also discussed in this work.

关键词: Metal oxide , oxide , nanostructures , field , emiss