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Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

《机械工程前沿(英文)》 2010年 第5卷 第1期   页码 98-105 doi: 10.1007/s11465-009-0088-8

摘要: To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.

关键词: micro-arc oxidation     local arc discharge     pulse power supply     magnesium alloy    

我国先进镁合金材料产业2035发展战略研究

李芳,管仁国,铁镝,刘楚明,乐启炽,宋江凤,曾小勤,蒋斌

《中国工程科学》 2020年 第22卷 第5期   页码 76-83 doi: 10.15302/J-SSCAE-2020.05.014

摘要:

本文在梳理我国镁合金材料产业发展现状的基础上,分析了其发展面临的国内外主要问题,展望了我国镁合金材料产业在高性能稀土镁轻质结构合金材料、高强高导热镁合金材料、高强高导电镁合金材料、超高强镁合金材料等11个方面的未来市场需求前景。面向2030年和2035年的阶段性发展规划,本文从提高自主创新能力、优化资源配置、加强企业合作力度、构建完善的镁合金材料整体研究体系、完善平台建设等方面提出了促进我国先进镁合金材料产业可持续发展的相关战略。最后,从注重研究体系的构建、优化产业发展格局、构建高质高效产业、完善配套政策体系、构建精尖人才体系等方面提出了对策建议,以期满足国民经济、国家重大工程和社会可持续发展对先进镁合金材料的需求。

关键词: 金属材料产业     镁合金     稀土镁合金材料     低能耗     高效率     2035    

汽车轻量化技术:铝/镁合金及其成型技术发展动态

付彭怀,彭立明,丁文江

《中国工程科学》 2018年 第20卷 第1期   页码 84-90 doi: 10.15302/J-SSCAE-2018.01.012

摘要:

为了推动我国汽车工业轻量化进程,文章从新材料、成型新技术、新应用三个方面对铝合金、镁合金两类轻金属材料的国内外研究动态进行了回顾,分析了两类轻金属材料在汽车工业应用的阻力,提出了我国汽车工业铝/镁合金可能的发展建议。

关键词: 汽车     轻量化     铝合金     镁合金     成型技术     发展动态    

Synthesis and characterization of magnesium hydroxide by batch reaction crystallization

Xingfu SONG, Shuying SUN, Dengke ZHANG, Jin WANG, Jianguo YU

《化学科学与工程前沿(英文)》 2011年 第5卷 第4期   页码 416-421 doi: 10.1007/s11705-011-1125-9

摘要: Magnesium hydroxide with high purity and uniform particle size distribution was synthesized by the direct precipitation method using MgCl and NaOH as reactive materials and NaCl as additive to improve the crystallization behavior of the product. The particle size distribution, crystal phase, morphology, and surface area of magnesium hydroxide were characterized by Malvern laser particle size analyzer, X-ray diffraction (XRD), scanning electron microscope (SEM) and Branauer-Emmett-Teller (BET) method, respectively. The purity of products was analyzed by the chemical method. The effects of synthesis conditions on the particle size distribution and water content (filtration cake) of magnesium hydroxide were investigated. The results indicated that feeding mode and rate, and reaction temperature had important effects on water content and the particle size distribution of the product, and sodium chloride improved the crystallization behavior of magnesium hydroxide. The ball-like magnesium hydroxides with the particle size distribution of 6.0–30.0 μm and purity higher than 99.0% were obtained. This simple and mild synthesis method was promising to be scaled up for the industrial production of magnesium hydroxide.

关键词: magnesium hydroxide     direct precipitation method     industrial crystallization     particle size distribution    

Experimental study on mechanical properties of a novel micro-steel fiber reinforced magnesium phosphate

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1047-1057 doi: 10.1007/s11709-021-0755-3

摘要: Magnesium phosphate cement (MPC) received increased attention in recent years, but MPC-based concrete is rarely reported. The micro-steel fibers (MSF) were added to MPC-based concrete to enhance its ductility due to the high brittleness in tensile and flexural strength properties of MPC. This paper investigates the effect of MSF volume fraction on the mechanical properties of a new pattern of MPC-based concrete. The temperature development curve, fluidity, cubic compressive strength, modulus of elastic, axial compressive strength, and four-point flexural strength were experimentally studied with 192 specimens, and a scanning electron microscopy (SEM) test was carried out after the specimens were failed. Based on the test results, the correlations between the cubic compressive strength and curing age, the axial and cubic compressive strength of MPC-based concrete were proposed. The results showed that with the increase of MSF volume fraction, the fluidity of fresh MPC-based concrete decreased gradually. MSF had no apparent influence on the compressive strength, while it enhanced the four-point flexural strength of MPC-based concrete. The four-point flexural strength of specimens with MSF volume fraction from 0.25% to 0.75% were 12.3%, 21.1%, 24.6% higher than that of the specimens without MSF, respectively.

关键词: magnesium phosphate cement-based concrete     micro-steel fibers     four-point flexural strength     compressive strength    

Effects of operational and structural parameters on cell voltage of industrial magnesium electrolysis

Ze Sun,Chenglin Liu,Guimin Lu,Xingfu Song,Jianguo Yu

《化学科学与工程前沿(英文)》 2015年 第9卷 第4期   页码 522-531 doi: 10.1007/s11705-015-1539-x

摘要: Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and used to calculate electric field at the steady state through the finite element analysis. Based on the simulation of the electric field, the operational and structural parameters, such as the current intensity, anode thickness, cathode thickness, and anode-cathode distance (ACD), were investigated to obtain the minimum cell voltage. The optimization is to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The results indicate that the effect of the current intensity on the voltage could be ignored and the effect of the ACD is obvious. Moreover, there is a linear decrease between the voltage and the thicknesses of the anode and cathode; and the anode-cathode working height also has a significant effect on the voltage.

关键词: finite element method     magnesium electrolysis cell     electric field    

Green process to recover magnesium chloride from residue solution of potassium chloride production plant

WANG Lin, HE Yunliang, WANG Yanfei, BAO Ying, WANG Jingkang

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 385-389 doi: 10.1007/s11705-008-0079-z

摘要: The green process to recover magnesium chloride from the residue solution of a potassium chloride production plant, which comes from the leach solution of a potash mine in Laos, is designed and optimized. The residue solution contains magnesium chloride above 25 wt-%, potassium chloride and sodium chloride together below 5 wt-% and a few other ions such as Br, SO and Ca. The recovery process contains two steps: the previous impurity removal operation and the two-stage evaporation-cooling crystallization procedure to produce magnesium chloride. The crystallized impurity carnallite obtained from the first step is recycled to the potassium chloride plant to recover the potassium salt. The developed process is a zero discharge one and thus fulfills the requirements for green chemical industrial production. The produced magnesium chloride is up to industrial criteria.

关键词: industrial production     chemical industrial     produced magnesium     chloride production     impurity carnallite    

搅拌摩擦焊镁合金隔声性能的研究

刘成武,钱林方

《中国工程科学》 2014年 第16卷 第8期   页码 93-98

摘要:

伴随搅拌摩擦焊在镁合金上的广泛应用,对其隔声特性研究尤为重要,基于自适应网格技术,对搅拌摩擦焊过程进行数值模拟,为后续声学计算提供约束模态,解决了材料属性难以确定的问题,一定程度上实现了焊接与声学的结合。自行设计和制造了混响箱,用以测量焊接镁合金板的隔声量,弥补了混响室测试小试件的不足。进而使用finite element-statistical energy analysis(FE-SEA)混合法计算焊接件的隔声量,与试验结果进行对比,吻合良好,表明此方法行之有效。通过对比焊接前后镁合金板件的隔声量,发现在吻合低谷区,焊接后板件的隔声有所降低。为了研究焊接参数对隔声的影响,分别改变焊接速度和搅拌头旋转速度,观察隔声量的变化,结果表明,这些参数都需要合理的设置,并非越大或者越小越好。

关键词: 搅拌摩擦焊     混响箱     FE-SEA混合法     焊接速度     搅拌头旋转速度    

Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by

H. Watamura, H. Marukawa, I. Hirasawa

《化学科学与工程前沿(英文)》 2013年 第7卷 第1期   页码 55-59 doi: 10.1007/s11705-013-1312-y

摘要: Relationship between magnesium ammonium phosphate (MAP) crystal properties and the filtration ability of hollow fiber membrane (HFM) were investigated. Phosphorus recovery process by crystallization has a problem that it produces a large amount of fine crystals. So improvement of the crystallization process by combining with filtration was discussed. MAP crystals were obtained by batch reaction crystallization and the filtration characteristics were investigated. The filtration was evaluated by the specific filtration resistance ( ) on HFM. Filtered slurry was prepared with each suspension density and crystal size distribution. The solution was filtered at constant pressure of 0.02 MPa and the filtration time on each filtrated volume was recorded. As a result, decreases exponentially with suspension density increasing from 0.25 g/L to 0.5 g/L and decreases moderately with suspension density increasing from 0.5 g/L to 1.5 g/L. of large crystals decreases exponentially at less suspension density than of small crystals does. Also, increases as the ratio of the fractured crystals increases.

关键词: membrane separation     crystallization     MAP    

Capture of carbon dioxide over porous solid adsorbents lithium silicate, lithium aluminate and magnesium

P. V. Korake, A. G. Gaikwad

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 215-226 doi: 10.1007/s11705-010-1012-9

摘要: The capturing process for carbon dioxide over porous solid adsorbents such as lithium silicate, lithium aluminate, and magnesium aluminate at pre- combustion temperatures was studied. Lithium silicate was prepared by the sol gel and solid fusion methods. The lithium silicate adsorbent was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and surface area. The capturing of carbon dioxide over lithium silicate, lithium aluminate, and magnesium aluminate was explored at different experimental conditions such as exposure time, temperature variation, and exposure carbon dioxide pressure. The capturing process for carbon dioxide was investigated over these adsorbents with variation of their metal mole ratios. The effect of the addition of (promoter) sodium, potassium, and cesium in the lithium silicate adsorbent was explored to investigate the variation of the capture of carbon dioxide over these adsorbents.

关键词: capturing CO2     lithium silicate     lithium aluminate     magnesium aluminate    

A stepwise process for carbon dioxide sequestration using magnesium silicates

Johan FAGERLUND, Experience NDUAGU, Ron ZEVENHOVEN, Inês ROMÃO,

《化学科学与工程前沿(英文)》 2010年 第4卷 第2期   页码 133-141 doi: 10.1007/s11705-009-0259-5

摘要: This work involves the production of magnesium in the form of Mg(OH) from serpentinite rock (nickel mine tailing) material followed by conversion into MgCO using a pressurised fluidised bed (PFB) reactor operating at 400°C–600°C and pressures up to 2.85MPa. Our approach is rooted in the thermodynamic fact that the reaction between Mg(OH) and gaseous CO forming MgCO and water releases significant amounts of heat. The main problem is, however, the chemical kinetics; the reaction is slow and has to be accelerated in order to be used in an economically viable process for large-scale (~1Mt/a) CO sequestration. We have constructed a lab-scale PFB reactor test-setup for optimising the carbonation reaction. At high enough temperatures and conversion levels the reaction should provide the heat for the proceeding Mg(OH) production step, making the overall process energy neutral. So far we have been able to achieve a conversion degree of 26% at 500°C and 2.85MPa after 30min (particle size 125–212μm). In this paper the test facility and our latest results and progress on CO mineral carbonation are summarised. Also, the possible integration of the iron as a feedstock for iron and steel production will be briefly addressed. An interesting side-effect of this carbon dioxide capture and storage (CCS) route is that significant amounts of iron are obtained from the serpentinite rock material. This is released during the Mg(OH) production and can be of great interest to the iron- and steel producing sector, which at the same time is Finland’s largest CO producer.

关键词: carbonation reaction     reactor     producer     large-scale     process    

A novel shape memory alloy actuated soft gripper imitated hand behavior

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0700-8

摘要: The limited length shrinkage of shape memory alloy (SMA) wire seriously limits the motion range of SMA-based gripper. In this paper, a new soft finger without silicone gel was designed based on pre bent SMA wire, and the finger was back to its original shape by heating SMA wire, rather than relying only on heat exchange with the environment. Through imitating palm movement, a structure with adjustable spacing between fingers was made using SMA spring and rigid spring. The hook structure design at the fingertip can form self-locking to further improve the load capacity of gripper. Through the long thin rod model, the relationship of the initial pre bent angle on the bending angle and output force of the finger was analyzed. The stress-strain model of SMA spring was established for the selection of rigid spring. Three grasping modes were proposed to adapt to the weight of the objects. Through the test of the gripper, it was proved that the gripper had large bending amplitude, bending force, and response rate. The design provides a new idea for the lightweight design and convenient design of soft gripper based on SMA.

关键词: shape memory alloy (SMA)     pre bent     wire     gripper     grasping mode     lightweight    

Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

《结构与土木工程前沿(英文)》 2023年 第17卷 第3期   页码 448-466 doi: 10.1007/s11709-022-0910-5

摘要: In this study, a numerical analysis was conducted on aluminum alloy reticulated shells (AARSs) with gusset joints under fire conditions. First, a thermal-structural coupled analysis model of AARSs considering joint semi-rigidity was proposed and validated against room-temperature and fire tests. The proposed model can also be adopted to analyze the fire response of other reticulated structures with semi-rigid joints. Second, a parametric analysis was conducted based on the numerical model to explore the buckling behavior of K6 AARS with gusset joints under fire conditions. The results indicated that the span, height-to-span ratio, height of the supporting structure, and fire power influence the reduction factor of the buckling capacity of AARSs under fire conditions. In contrast, the reduction factor is independent of the number of element divisions, number of rings, span-to-thickness ratio, and support condition. Subsequently, practical design formulae for predicting the reduction factor of the buckling capacity of K6 AARSs were derived based on numerical analysis results and machine learning techniques to provide a rapid evaluation method. Finally, further numerical analyses were conducted to propose practical design suggestions, including the conditions of ignoring the ultimate bearing capacity analysis of K6 AARS and ignoring the radiative heat flux.

关键词: aluminum alloy reticulated shell     gusset joint     numerical analysis     fire resistance    

Protein phosphatase magnesium-dependent 1δ is a novel tumor marker and target in hepatocellular carcinoma

null

《医学前沿(英文)》 2016年 第10卷 第1期   页码 52-60 doi: 10.1007/s11684-016-0433-3

摘要:

Hepatocellular carcinoma (HCC) is a lethal liver malignancy worldwide. In this study, we reported that protein phosphatase magnesium-dependent 1δ (PPM1D) was highly expressed in the majority of HCC cases (approximately 59%) and significantly associated with high serum α-fetoprotein (AFP) level (P= 0.044). Kaplan-Meier and Cox regression data indicated that PPM1D overexpression was an independent predictor of HCC-specific overall survival (HR, 2.799; 95% CI, 1.346–5.818, = 0.006). Overexpressing PPM1D promoted cell viability and invasion, whereas RNA interference-mediated knockdown of PPM1D inhibited proliferation, invasion, and migration of cultured HCC cells. In addition, PPM1D suppression by small interfering RNA decreased the tumorigenicity of HCC cells in vivo. Overall, results suggest that PPM1D is a potential prognostic marker and therapeutic target for HCC.

关键词: PPM1D     hepatocellular carcinoma     prognosis     target therapy    

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

《结构与土木工程前沿(英文)》 2022年 第16卷 第12期   页码 1565-1580 doi: 10.1007/s11709-022-0867-4

摘要: This study proposes a shape optimization method for K6 aluminum alloy spherical reticulated shells with gusset joints, considering geometric, material, and joint stiffness nonlinearities. The optimization procedure adopts a genetic algorithm in which the elastoplastic non-linear buckling load is selected as the objective function to be maximized. By confinement of the adjustment range of the controlling points, optimization results have enabled a path toward achieving a larger elastoplastic non-linear buckling load without changing the macroscopic shape of the structure. A numerical example is provided to demonstrate the effectiveness of the proposed method. In addition, the variation in structural performance during optimization is illustrated. Through parametric analysis, practical design tables containing the parameters of the optimized shape are obtained for aluminum alloy spherical shells with common geometric parameters. To explore the effect of material nonlinearity, the optimal shapes obtained based on considering and not considering material non-linear objective functions, the elastoplastic and elastic non-linear buckling loads, are compared.

关键词: shape optimization     aluminum alloy     spherical reticulated shell     non-linear buckling     material nonlinearity     genetic algorithm    

标题 作者 时间 类型 操作

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

期刊论文

我国先进镁合金材料产业2035发展战略研究

李芳,管仁国,铁镝,刘楚明,乐启炽,宋江凤,曾小勤,蒋斌

期刊论文

汽车轻量化技术:铝/镁合金及其成型技术发展动态

付彭怀,彭立明,丁文江

期刊论文

Synthesis and characterization of magnesium hydroxide by batch reaction crystallization

Xingfu SONG, Shuying SUN, Dengke ZHANG, Jin WANG, Jianguo YU

期刊论文

Experimental study on mechanical properties of a novel micro-steel fiber reinforced magnesium phosphate

期刊论文

Effects of operational and structural parameters on cell voltage of industrial magnesium electrolysis

Ze Sun,Chenglin Liu,Guimin Lu,Xingfu Song,Jianguo Yu

期刊论文

Green process to recover magnesium chloride from residue solution of potassium chloride production plant

WANG Lin, HE Yunliang, WANG Yanfei, BAO Ying, WANG Jingkang

期刊论文

搅拌摩擦焊镁合金隔声性能的研究

刘成武,钱林方

期刊论文

Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by

H. Watamura, H. Marukawa, I. Hirasawa

期刊论文

Capture of carbon dioxide over porous solid adsorbents lithium silicate, lithium aluminate and magnesium

P. V. Korake, A. G. Gaikwad

期刊论文

A stepwise process for carbon dioxide sequestration using magnesium silicates

Johan FAGERLUND, Experience NDUAGU, Ron ZEVENHOVEN, Inês ROMÃO,

期刊论文

A novel shape memory alloy actuated soft gripper imitated hand behavior

期刊论文

Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

期刊论文

Protein phosphatase magnesium-dependent 1δ is a novel tumor marker and target in hepatocellular carcinoma

null

期刊论文

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

期刊论文