检索结果-南通市图书馆

Processing soft ferromagnetic metallic glasses:on novel cooling strategies in gas atomization,hydrogen enhancement,and consolidation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第24期59卷 26-36页

作者： n.Ciftci n.Yodoshi S.Armstrong L.Madler v.Uhlenwinkel Leibniz Institute for Materials Engineering IWT Badgasteiner Straße 328359BremenGermany Cooperative Research and Development Center for Advanced Materials Institute for Materials ResearchTohoku University2-2-1 KatahiraAoba-kuSendai980-8577Japan University of Bremen Faculty of Production EngineeringBadgasteiner Straße 128359BremenGermany

Processing soft ferromagnetic glass-forming alloys through gas atomization and consolidation is the most effective technique to produce bulk *** commercial viability of these materials depends on commercial purity ***,crystallization in commercial purity feedstock is several orders of magnitude faster than in high purity *** production of amorphous powders with commercial purity requires high cooling rates,which can only be achieved by extending the common process window in conventional gas *** development of novel cooling strategies during molten metal gas atomization on two model alloys({(Fe0.6Co0.4)0.75B0.2Si0.05}96nb4 and Fe76B10Si9P5)is *** inducement during liquid quenching significantly improved the glass-forming ability and soft magnetic properties of{(Fe0.6Co0.4)0.75B0.2Si0.05}96nb4 *** plasma sintering experiments verified that amorphous rings could be produced regardless of the cooling strategies *** the saturation magnetization was almost unaffected by consolidation,the coercivity increased slightly and permeability decreased *** magnetic properties of the final bulk samples were independent of feedstock *** developed cooling strategies provide a great opportunity for the commercialization of soft ferromagnetic glass-forming alloys with commercial purity.

关键词： Gas atomization Amorphous powders Metallic glass Cooling Quenching Heat transfer Hydrogen

Study on Surface Engineering of normalized Steels Subjected To Machine Hardening

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第05B期25卷 1329-1332页

作者： n.Alagurmurthi K.Palaniradja v.Soundararajan Department of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Engineering the surfaces of components to improve the life and performance of parts used in automotive and aerospace engineering is the active area of research. Suitable Thermal/ Mechanical/Thermo mechanical surface engineering treatments will produce extensive rearrangement of atoms in metals and alloys and corresponding marked variations in Physical, Chemical and Mechanical properties. Among the more important of these treatments are heat treatment processes such as hardening by Quenching, Induction hardening and Case Carburizing which rely on phase transformations to produce desired changes in mechanical properties. Other processes where phase transformation occur are casting, welding and machining etc. [1] Phase transformation may be homogeneous or heterogeneous. Homogeneous involves rearrangements in the structure of the material taking place simultaneously in all parts of the solid, while the heterogeneous transformation involves structural changes which are more localized. Alternatively they could be called as Isothermal and nonisothermal transformation. But irrespective of the classification, these transformations alter the structure of the material giving rise to changes in the mechanical and physical properties of the processed material. It is of interest to review some consequences of surface modification in isothermal (normalizing) and nonisothermal transformations (Machining) of low carbon steels.

关键词：正火钢研磨硬化比能能量区别速率

On The Enhancement of Wear Resistance of Hardened Carbon Tool Steel (AISI 1095) With Cryogenic Quenching

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第5期25卷 531-535页

作者： v.Soundararajan n.Alagurmurthi K.Palaniradja Department of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Many experimental investigations reveal that it is very difficult to have a completely martensitic structure by any hardening process. Some amount of austenite is generally present in the hardened steel. This austenite existing along with martensite is normally referred as the retained austenite. The presence of retained austenite greatly reduces the mechanical properties and such steels do not develop maximum hardness even after cooling at rates higher than the critical cooling rates. Strength can be improved in hardened steels containing retained austenite by a process known as cryogenic quenching. Untransformed austenite is converted into martensite by this treatment. This conversion of retained austenite into martensite results in increased hardness, wear resistance and dimensional stability of steel. Wear can be defined as the progressive loss of materials from the operating surface of a body occurring as a result of relative motion at the surface. Hardness, load, speed, surface roughness, temperature are the major factors which influences wear. Many studies on wear indicate that increasing hardness decreases the wear of a material. With this in mind, to study the surface wear on a surface modified (Cryogenic treated) steel material an attempt has been made in this paper. In this study as a Part -I Hardening was carried out on carbon tool steel (AISI 1095) of different L/D ratio with conventional quenchants like purified water, aqueous solution and Hot mineral oil. As a Part -II hardening was followed by quenching was carried out as said in Part-1 and the hardened specimen were quenched in liquid nitrogen which is at sub zero condition. The specimens were tested for its microstructure, hardness and wear loss. The results were compared and analyzed. The alloying elements increases the content of retained austenite hence the material used was AISI1095 (Carbon 0.9%, Si 0.2%, MnO.4% and the rest Iron)

关键词： AISI1095钢液态氮低温淬火抗磨损性

CP violation in ∧b → ∧l^＋l^- Decay in the Four-Generation Standard Model

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2010年第4期27卷 63-66页

作者： v. Bashiry n. Shirkhanghah K. Zeynali Engineering Faculty Cyprus International University Via Mersin 10 Turkey Islamic Azad University Khalkhal Branch Valiasr St. Khalkhal Iran Department of Sciences Ardabil University of Medical Sciences Daneshgah St. Ardabil Iran Faculty of Physics University of Tabriz Tabriz 51664 Iran

We present the first study of CP asymmetry in ∧b → ∧l^＋l^- decay when a new weak phase comes through the extension of three-generation standard model to the four-generation standard model. Taking ｜vt′s^＊vt′b｜ = 0.01, 0.02, 0.03 with phase {60° - 120°}, which is consistent with the b → sl^＋l^- rate and the Bs mixing parameter △mBs, we find out that CP asymmetry is quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, in particular, to search for the fourth generation quarks （t′, b′） via their indirect manifestations in loop diagrams.

关键词： Particle physics and field theory

Bending sensor based on flexible spin valve

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2023年第5期32卷 655-661页

作者： L I naumova R S Zavornitsyn M A Milyaev n G Bebenin A Y Pavlova M v Makarova I K Maksimova v v Proglyado A A Zakharov v v Ustinov M.n.Miheev Institute of Metal Physics Ural BranchRussian Academy of SciencesS.Kovalevskoi Street 18Ekaterinburg 620990Russia

Flexible spin valves were prepared by magnetron sputtering on polyimide substrates. The buffer layer that reduces significantly the effect of the polymer substrate on the spin valve microstructure and magnetoresistive properties was revealed. Bending deformation was applied to the microobjects based on the flexible spin valves in parallel to anisotropy axes. It was revealed that during the bend the magnetoresistance changes due to the joint impact of both the change of the magnetic field projection on the film plane and the change of the magnetic properties of the ferromagnetic layers. The obtained dependences have been used in construction of bending sensor, in which the flexible spin valve microstripes were united into the Wheatstone bridge.

关键词： spin valve polymer substrate magnetostriction magnetic anisotropy

Analysis on Phase Transformation (ATP) Using Computational Thermal Principles (CTP)

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第05B期25卷 716-719页

Computer analysis based on computational thermal principles to predict the transformation kinetics in steels at varying temperatures is of great practical importance in different areas of heat treatment. As a result, using the theory of transient state heat conduction with convective boundary conditions, an efficient program named "ATP" (Analysis on Phase Transformation) has been developed to determine the temperature distribution under different quenching conditions for different geometries such as plate, cylinder and sphere. In addition to these the microstructures and the corresponding hardness developed during quenching are predicted using Time Temperature Transformation (TTT) diagram incorporated in the analysis. To approve our work, dilation curves, Heisler charts and time-temperature history curve have been generated. This paper deals with basic objective of the program (ATP) determination of temperature, microstructure and hardness distribution and also includes an online prediction of austenite-pearlite and austenite-martensite transformation in steels along with the corresponding retained fractions. The quenching of a cylinder in gases, liquids and liquid metals is analyzed to show the non-liner effect of cylinder diameter on the temperature and microstructures. Further in the program we have considered a typical 1080 steel cylinders quenched in water for predicting and comparing the program results with experimental values and can be extended even to other grades of steels. The numerical results of program are found to be in good agreement with the experimental data obtained. Finally the quenching process analysis described in the study appears to be a promising tool for the design of heat-treatment process parameters for steels.

关键词：热处理相位变换 ATP 温度分布冷却曲线 CTP

Three-dimensional mixed convection stagnation-point fow past a vertical surface with second-order slip velocity

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 641-652页

作者： A.v.ROSCA n.C.ROSCA I.POP Department of Statistics-Forecasts-Mathematics Faculty of Economics and Business AdministrationBabes-Bolyai UniversityCluj-Napoca 400084Romania Department of Mathematics Faculty of Mathematics and Computer ScienceBabes-Bolyai UniversityCluj-Napoca 400084Romania Academy of Romanian Scientists 3 Ilfov StreetBucharest 050044Romania

This study is concerned with the three-dimensional(3D)stagnation-point for the mixed convection flow past a vertical surface considering the first-order and secondorder velocity *** the authors’knowledge,this is the first study presenting this very interesting *** partial differential equations for the flow problem are transformed into nonlinear ordinary differential equations(ODEs)by using appropriate similarity *** ODEs with the corresponding boundary conditions are numerically solved by utilizing the bvp4c solver in MATLAB programming *** effects of the governing parameters on the non-dimensional velocity profiles,temperature profiles,skin friction coefficients,and the local nusselt number are presented in detail through a series of graphs and ***,it is reported that the reduced skin friction coefficient decreases for the assisting flow situation and increases for the opposing flow *** numerical computations of the present work are compared with those from other research available in specific situations,and an excellent consensus is *** exciting feature for this work is the existence of dual *** important remark is that the dual solutions exist for both assisting and opposing flows.A linear stability analysis is performed showing that one solution is stable and the other solution is not *** notice that the mixed convection and velocity slip parameters have strong effects on the flow *** effects are depicted in graphs and discussed in this *** obtained results show that the first-order and second-order slip parameters have a considerable effect on the flow,as well as on the heat transfer characteristics.

关键词： three-dimensional(3D)mixed convection flow stagnation point flow first-order slip velocity second-order slip velocity numerical solution stability analysis

numerical forecasting surge in a piping of compressor shops of gas pipeline network

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1775-1788页

作者： SELEZnEv v. E. PRYALOv S. n. Physical & Technical Center Joint Stock Company Sarov 607180 Russia

This paper presents a method of forecasting stable operation of gas compressor unit (GCU) centrifugal supercharger (CFS) installed on a piping of compressor shops servicing gas pipelines. The stability of superchargers operation is assessed in relation to the phenomenon of surge. Solution of this problem amounts to the development and numerical analysis of a set of ordinary differential equations. The set describes transmission of gas through a compressor shop as a fluid dynamics model with lumped parameters. The proposed method is oriented to wide application by specialists working in the gas industry. The practical application of this method can use all-purpose programming and mathematical software available to specialists of gas companies.

关键词： Gas pipelines Compressor station Centrifugal supercharger (CFS) Surge numerical simulation

Evaluation of Process Capability in Gas Carburizing Process to Achieve Quality through Limit Design Concept

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第5期25卷 395-397页

作者： K. Palaniradja n. Alagumurthi v. Soundararajan Department of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Steel is the most important metallic material used in industry. This is because of the versatility of its engineering properties under different conditions. In one condition it can be very mild, soft and suitable for any forming operation. In another condition the same steel can be very hard and strong. This versatility is made possible by the different heat treatments that the steel can be subject to. One such treatment is Gas carburizing. This is the most widely used process for surface hardening of low carbon steels. In this method the surface composition of the steel changes by diffusion of carbon and or nitrogen and result in hard outer surface with good wear resistance properties. A striking feature of Gas Carburizing process is that in this process the original toughness and ductility remains unaffected even after heat treatment. 3% nickel chromium case hardened low carbon steels are widely used for critical automotive and machine applications such as rack and pinion, gears, camshaft, valve rocker shafts and axles which requires high fatigue resistance. Fatigue behaviour of case carburized parts depends to a great extent on the correct combination of Hardness Penetration Depth (HPD) and the magnitude of hardness at the surface and beneath the surface with low size and shape distortion. In order to reduce the manufacturing costs in terms of material consumption and elimination of the number of processing steps, the effect of Gas carburizing parameters on the fatigue behaviour should already be considered in the parameter design stage. Therefore it is of importance to optimize the gas carburizing process variables to attain quality products with respect to hardness and case depth. In the present paper, the evaluation of process capability was carried out through a Limit Design Concept called orthogonal array design of experiment. To optimize the process variables the influence of several parameters (Holding time, Carbon potential, Furnace temperature and Quench

关键词：气体渗碳最优化碳势存放时间消火时间炉温