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Effect of hydro co-extrusion on microstructure of duo-cast Al3003/Al4004 clad materials

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Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 75-80页

作者： In-Soo SON Sang-Pill LEE Jin-Kyung LEE Woo-Cheol KIM Ji-Seon MOON Sangmok LEE Jong-sup LEE Yong-bae KIM Geun-Ahn LEE dong-su bae Department of Mechanical Engineering Dong-Eui University Busan Korea Department of Advanced Materials Engineering Dong-Eui University Busan Korea Advanced Forming Tech. Center Korea Institute of Industrial Technology Incheon Korea

The effects of hydro co-extrusion on the microstructure changes of aluminum hybrid duo-cast Al 3003/Al 4004 clad materials were studied. The specimen of duo-cast Al 3003/Al 4004 clad materials was in circle shape, and was composed of Al 3003(outside) and Al 4004(inside) materials. The specimen was extruded by the hydro co-extrusion equipment. The manufacturing conditions of the specimen were 423 K in temperature and 5 in extrusion ratio. The dimensions of the specimen were 80 mm in diameter of the Al 4004 material and 35 mm in thickness of the Al 3003 material before the hydro co-extrusion process, and 30 mm in diameter and about 5 mm in thickness after the extrusion process, respectively. The microstructure and the hardness for two specimens were investigated. The hardness value of cross section in the duo-cast Al 3003/Al 4004 clad materials before the extrusion process was increased in form of the parabola toward the center. However, after the extrusion process, it was almost constant in the portion of Al 4004 material. Lots of big voids above 1 mm in diameter in the specimen existed in the interfacing region of Al 3003 and Al 4004 materials before the extrusion process. These big voids disappeared after the process of hydro co-extrusion.

关键词： clad materials hydro co-extrusion process duo-casting microstructure

Advanced electron microscopy characterization of nanomaterials for catalysis

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Green Energy & Environment 2017年第2期2卷 70-83页

作者： dong su Center for Functional Nanomaterials Brookhaven National Laboratory

Transmission electron microscopy(TEM) has become one of the most powerful techniques in the fields of material science, inorganic chemistry and nanotechnology. In terms of resolutions, advanced TEM may reach a high spatial resolution of 0.05 nm, a high energy-resolution of 7 meV. In addition, in situ TEM can help researchers to image the process happened within 1 ms. This paper reviews the recent technical progresses of applying advanced TEM characterization on nanomaterials for catalysis. The text is organized based on the perspective of application: for example, size, composition, phase, strain, and morphology. The electron beam induced effect and in situ TEM are also introduced. I hope this review can help the scientists in related fields to take advantage of advanced TEM to their own researches.

关键词： Advanced TEM Nanomaterials Catalysts In situ

A Class of Finite-Dimensional Representations of U_q(sl_2)

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Acta Mathematica Sinica,English Series 2013年第9期29卷 1703-1712页

作者： dong Ming CHENG dong su Department of Mathematics and Applied Mathematics He'nan University of Science and Technology

In order to study a class of finite-dimensional representations of Uq（sl2）, we deal with the quotient algebra Uq （m, n, b） of quantum group Uq（sl2） with relations Kr=1, Emr=b, Fnr=0 in this paper, where q is a root of unity. The algebra Uq（m, n, b） is decomposed into a direct sum of indecomposable （left） ideals. The structures of indecomposable projective representations and their blocks are determined.

关键词： Quantum group representation root of unity

Lightweight and large-scale rGO reinforced SiBCN aerogels with hierarchical cellular structures exposed to high-temperature environments

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Journal of Materials Science & Technology 2024年第12期179卷 145-154页

作者： Huijie Wang Zhiwei Chen dong su Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjin 300350China

SiBCN ceramic aerogel is an ideal potential candidate for ultra-high temperature thermal insulation due to its unique microscopic pore structure combined with the excellent thermal stability of SiBCN ***,reduced graphene oxide(rGO)modified SiBCN aerogels(rGO/SiBCN)were prepared through solvothermal,freeze-casting and pyrolysis,and the dimension of the aerogel is up toΦ130 mm×28 *** density of the rGO/SiBCN aerogel is as low as 0.024 g/cm^(3) and the microstructural regulation is achieved by controlling the rGO content in the *** hierarchical cellular structure endows the aerogel with a high specific surface area(148.6 m^(2)/g)and low thermal conductivity(0.057 W m^(-1) K^(-1)).The 10 mm-thick sample exhibits excellent thermal insulation and ablation resistance,as evidenced by its ability to reduce the temperature from~1100℃to~180℃under the intense heat of a butane ***,benefiting from the ultrahigh-temperature stability of SiBCN,the rGO/SiBCN aerogel exhibits good thermal stability up to 1200℃in argon and short-oxidation resistance at 800℃in ***-fore,the rGO/SiBCN aerogel with superior overall performance could expand its practical application in high-temperature thermal insulation under extreme environments.

关键词： rGO/SiBCN Lightweight Large size Hierarchical cellular structure Thermal insulation

非对称型假体设计及全膝关节置换后的力学分析

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中国组织工程研究 2025年第3期29卷 510-516页

作者：苏德君董万鹏董跃福张吉超张震上海工程技术大学材料科学与工程学院上海市201620 徐州医科大学附属连云港医院江苏省连云港市222061

背景:全膝关节置换是治疗膝关节晚期病症的有效手段,但假体衬垫容易因内部应力变化而产生磨损失效,寿命有限且术后患者的活动能力降低。如何对假体进行改进设计来满足患者更多的需求是假体研究的重要方向。目的:基于半月板的形态设计一... 详细信息

背景:全膝关节置换是治疗膝关节晚期病症的有效手段,但假体衬垫容易因内部应力变化而产生磨损失效,寿命有限且术后患者的活动能力降低。如何对假体进行改进设计来满足患者更多的需求是假体研究的重要方向。目的:基于半月板的形态设计一种非对称型假体,并与对称设计的后稳定型假体进行比较,分析2种假体的应力分布情况和衬垫的接触面积变化,以探究非对称型假体设计是否存在优势。方法:通过有限元方法对1例膝骨关节炎患者进行模拟截骨和假体装配,建立基于非对称型假体及对称设计的后稳定型假体的全膝关节置换术后膝关节模型。在0°,10°,20°,30°的屈膝条件下,探究股骨假体、胫骨假体以及衬垫上的Mises应力,并通过对比衬垫内外侧的接触面积,分析全膝关节置换后膝关节生物力学变化和运动行为的改变。结果与结论:(1)在0°-30°的屈膝过程中,2种假体衬垫上的Mises应力峰值均表现出先减小后增大的趋势,且内侧始终大于外侧。(2)非对称型设计的假体与后稳定型假体相比,应力峰值更低;在屈膝30°时,非对称型假体衬垫内外侧的Mises应力峰值分别为15.81 MPa和11.95 MPa,后稳定型衬垫为16.70 MPa和13.76 MPa,两者内侧差值约为5.33%,而外侧则相差13.15%;对比股骨假体和胫骨假体上的Mises应力峰值,非对称型假体在屈膝过程中始终低于后稳定型假体。(3)在0°站立位时,后稳定型假体衬垫的内侧接触面积为17.96 mm^(2)、外侧为34.10 mm^(2);而非对称型假体衬垫的内外侧接触面积分别为105.47 mm^(2)和107.80 mm^(2),具有更大的接触面积且两侧差距更小。(4)结果表明,非对称型假体的生物力学表现更好,且能够对维持膝关节稳定性、提升关节活动度有所帮助。这种设计能够在一定程度上还原膝关节以内侧髁为轴进行外旋的运动机制,是一种更为有效的膝关节假体选择方案。

关键词：膝关节全膝关节置换非对称型假体设计生物力学有限元分析

Production of Integrated Automotive Part in High Pressure Diecasting Process Using Salt Core

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Journal of Rare Earths 2004年第Z2期22卷 57-60页

作者： Ki-bae Kim Hyun-Kwang Seok Jun-su Kim Advanced Materials Research Center Korea Institute of Science and TechnologyP.O.Box 131CheongryangSeoul130-650Korea Advanced Materials Research CenterKorea Institute of Science and TechnologyP.O.Box 131CheongryangSeoul130-650Korea Research & Development CenterTechnology Union Co.Ltd742-1Paeksok-dongChonan-siChungchongnam-do330-220Korea

A new concept of salt core, a melting temperature of which is lower than the solidus temperature of cast alloy,was introduced to produce an integrated casting part having a complicated inner shape or requiring under-cut in high pressure die casting or squeeze casting process. A salt core, named a fusible core in this paper because the salt core can be easily extracted just as holding at a temperature under a solidus temperature of a casting alloy, was developed and applied to produce a fuel control part for automotive GDI engine in high pressure diecasting machine. A different salt material of a lower melting temperature than that of A1 alloy was mixed with a different ceramic particulate to improve a thermo-physical property of fusible core. The thermo-physical property of the fusible core was measured and a weight faction of the ceramic particulate was optimized. The selected core materials were poured in metallic mold by gravity to produce a fusible core for a fuel control part for automotive GDI engine. The fuel control part, which the fusible core was included inside, was successful to fabricate in a conventional diecasting machine with no melting of fusible core during casting.

关键词： salt core high pressure diecasting casting part for automotive fusible core

CAVITATION CONTROL BY AERATION AND ITS COMPRESSIBLE CHARACTERISTICS

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Journal of Hydrodynamics 2006年第4期18卷 499-504页

作者： dong Zhi-yong su Pei-lan School of Civil Engineering and Architecture Zhejiang University of Technology Hangzhou 310032 China School of Forestry Shanxi Agricultural University Taigu 030801 China

This paper presents an experimental investigation and a theoretical analysis of cavitation control by aeration and its compressible characteristics at the flow velocity V=20m/s-50m/s. Pressure waveforms with and without aeration in cavitation region were measured. The variation of compression ratio with air concentration was described, and the relation between the least air concentration to prevent cavitation erosion and flow velocity proposed based on our experimental study. The experimental results show that aeration remarkably increases the pressure in cavitation region, and the corresponding pressure wave exhibits a compression wave/shock wave. The pressure increase in cavitation region of high-velocity flow with aeration is due to the fact that the compression waves/shock wave after the flow is aerated. The compression ratio increases with air concentration rising. The relation between flow velocity and least air concentration to prevent cavitation erosion follows a semi-cubical parabola. Also, the speed of sound and Mach number of high-velocity aerated flow were analyzed.

关键词： cavitation control by aeration compression wave/shock wave least air concentration speed of sound compression ratio

Resonance scattering characteristics of double-layer spherical particles

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Particuology 2012年第1期10卷 117-126页

作者： Xuejin dong Mingxu su Xiaoshu Cai Institute of Particle and Two-Phase Flow Measurement University of Shanghai for Science and Technology Shanghai 200093 China

Based on the principle of ultrasonic resonance scattering, sound-scattering characteristics of double-layer spherical particles in water were numerically studied in this paper. By solving the equations of the scat- tering matrix, the scattering coefficient determined by the boundary conditions can be obtained, thus the expression for the sound-scattering function of a single double-layer spherical particle can be derived. To describe the resonance scattering characteristics of a single particle, the reduced scattering cross section and reduced extinction cross section curves were found through numerical calculation. Similarly, the numerically calculated sound attenuation coefficient curves were used to depict the resonance scattering characteristics of monodisperse and poIydisperse particles. The results of numerical calculation showed that, for monodisperse particles, the strength of the resonance was mainly related to the particle size and the total number of particles; while for polydisperse particles, it was primarily affected by the particle size, the coverage of the particle size distribution and the particle concentration.

关键词： UltrasonicResonance scatteringDouble-layerPolydisperseVisco-elastic

Experimental study of effect of post processing on fracture toughness and fatigue crack growth performance of selective laser melting Ti-6Al-4V

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Chinese Journal of Aeronautics 2019年第10期32卷 2383-2393页

作者： Haiying ZHANG Dengke dong Shaopu su An CHEN Aircraft Strength Research Institute

For Ti-6Al-4V,a titanium alloy increasingly used in aerospace structure,selective laser melting(SLM)is an attractive additive manufacturing technology,which is attributed to its complex construction capability with high accuracy and good surface *** order to obtain qualified mechanical properties,SLM parameters and post processing should be tailored for diverse service *** toughness and fatigue crack growth(FCG)behavior are critical characteristics for damage tolerance evaluation of such metallic structures,and they are affected by post processing technologies *** objective of this study is to obtain the fracture toughness and fatigue crack growth behavior of Ti-6Al-4V manufactured by SLM,and to evaluate the influence of post-SLM thermomechanical treatment and surface *** toughness and FCG tests were performed for SLM Ti-6Al-4V in three types of post processing status:as-built,heat treated and hot isostatically pressed(HIPed),*** with as-built and machined surface were *** microstructure and fractography were analyzed as well in order to investigate the relevance among manufacture process,microstructure and mechanical *** results demonstrate that as-built SLM Ti-6Al-4V presents poor ductility and FCG behavior due to martensitic microstructure and residual *** heat treatment and hot isostatic pressing improve the plane-stress fracture toughness and FCG performance considerably,while surface machining shows slight effect.

关键词： Fracture toughness Fatigue crack growth Heat treatment Selective laser melting surface roughness