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Room temperature liquid metal: its melting point, dominating mechanism and applications

Junheng FU, Chenglin ZHANG, Tianying LIU, Jing LIU

《能源前沿（英文）》 2020年第14卷第1期页码 81-104 doi: 10.1007/s11708-019-0653-8

摘要： The room temperature liquid metal (LM) is recently emerging as a new class of versatile materials with fascinating characteristics mostly originated from its simultaneous metallic and liquid natures. The melting point is a typical parameter to describe the peculiarity of LM, and a pivotal factor to consider concerning its practical applications such as phase change materials (PCMs) and advanced thermal management. Therefore, the theoretical exploration into the melting point of LM is an essential issue, which can be of special value for the design of new LM materials with desired properties. So far, some available strategies such as molecular dynamics (MD) simulation and classical thermodynamic theory have been applied to perform correlative analysis. This paper is primarily dedicated to performing a comprehensive overview regarding typical theoretical strategies on analyzing the melting points. It, then, presents evaluations on several factors like components, pressure, size and supercooling that may be critical for melting processes of liquid metal. After that, it discusses applications associated with the characteristic of low melting points of LM. It is expected that a great many fundamental and practical works are to be conducted in the coming future.

关键词： melting point liquid metal crystal thermodynamics molecular dynamics

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Phase change effect of low melting point metal for an automatic cooling of USB flash memory

Haoshan GE, Jing LIU

《能源前沿（英文）》 2012年第6卷第3期页码 207-209 doi: 10.1007/s11708-012-0204-z

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A steam dried municipal solid waste gasification and melting process

Gang XIAO, Baosheng JIN, Mingjiang NI, Kefa CEN, Yong CHI, Zhongxin TAN

《环境科学与工程前沿（英文）》 2011年第5卷第2期页码 193-204 doi: 10.1007/s11783-010-0268-0

摘要： Considering high-moisture municipal solid waste (MSW) of China, a steam dried MSW gasification and melting process was proposed, the feasibility was tested, and the mass and energy balance was analyzed. Preliminary experiments were conducted using a fixed-bed drying apparatus, a 200 kg per day fluidized-bed gasifier, and a swirl melting furnace. Moisture percentage was reduced from 50% to 20% roughly when MSW was dried by slightly superheated steam of 150°C–350°C within 40 min. When the temperature was less than 250°C, no incondensable gas was produced during the drying process. The gasifier ran at 550°C–700°Cwith an air equivalence ratio (ER) of 0.2–0.4. The temperature of the swirl melting furnace reached about 1240°C when the gasification ER was 0.3 and the total ER was 1.1. At these conditions, the fly ash concentration in the flue gas was 1.7 g·(Nm ) , which meant over 95% fly ash was trapped in the furnace and discharged as slag. 85% of Ni and Cr were bound in the slag, as well as 60% of Cu. The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97% when MSW is dried by steam of 200°C. The boiler heat efficiency is sensitive to three important parameters, including the temperature of preheated MSW, the moisture percentage of dried MSW and the fly ash percentage in the total ash.

关键词： municipal solid waste (MSW) steam drying gasification and melting

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用于介观模拟电子束选区熔化的数据挖掘技术 Article

钱亚, 闫文韬, 林峰

《工程（英文）》 2019年第5卷第4期页码 746-754 doi: 10.1016/j.eng.2019.06.006

摘要：

在电子束选区熔化技术（EBSM）工艺中，制造部件的性质受到每一道熔道沉积质量的影响。然而，熔道的形成受到各种物理现象和工艺参数的支配，这些参数之间的相关性十分复杂，难以通过实验得出。近来，介观建模技术已成为模拟电子束（EB）熔化过程以及揭示特定熔道形貌的形成机制的手段。尽管如此，人们对工艺参数与熔道特征之间的相关性尚未有定量的理解。本文从介观模拟的结果出发，研究了熔道的形态特征，同时引入了熔道宽度和高度等关键性描述指标，以便从数值上评估沉积质量。本文还定量研究了各种工艺参数的影响，从而导出了工艺条件和熔道特征之间的相关性。最后，本文提出了一种由介观建模和数据挖掘技术组成的仿真驱动优化框架，并讨论了框架的潜力和局限性。

关键词：电子束选区熔化介观模型数据挖掘

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Investigation on multiple-melting behavior of nano-CaCO3/polypropylene composites

LIN Zhidan, ZENG Chunlian, MAI Kancheng

《化学科学与工程前沿（英文）》 2007年第1卷第1期页码 81-86 doi: 10.1007/s11705-007-0017-5

摘要： The multiple melting-peak behavior of polypropylene (PP) in nano-CaCO/PP composites and modified nano-CaCO/PP composites were investigated under the condition of isothermal crystallization and nonisothermal crystallization. The result indicated that the addition of nano-CaCO markedly increased the crystallization temperatures of PP and induced the formation of the β-crystal of PP. The crystallization temperatures of nano-CaCO/PP composites modified by reactive monomers were further increased, but the melting-peak intensity of the β-crystal of PP was not greatly influenced. While in the presence of dicumyl peroxide, nano-CaCO/PP composites modified by reactive monomers led to the significant increase in the melting-peak intensity of the β-crystal of PP. The double melting-peak of PP was observed, which was attributed to the formation of two kinds of different crystallization forms of α-crystal or β-crystal during the crystallization of PP. With the increase of crystallization temperatures, the double melting-peak moved toward the high-temperature side. The intensity of high-temperature melting peak was higher than that of low-temperature melting peak in nano-CaCO/PP composites. While in modified nano-CaCO/PP composites crystallized at higher temperature, the intensity of high-temperature melting peak was lower than that of low-temperature melting peak. The isothermal crystallization time had little effect on the melting temperatures.

关键词： polypropylene nano-CaCO/PP presence melting-peak behavior low-temperature

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Differences in microstructure and properties between selective laser melting and traditional manufacturing

Bo SONG,Xiao ZHAO,Shuai LI,Changjun HAN,Qingsong WEI,Shifeng WEN,Jie LIU,Yusheng SHI

《机械工程前沿（英文）》 2015年第10卷第2期页码 111-125 doi: 10.1007/s11465-015-0341-2

摘要：

Selective laser melting (SLM), as one of the additive manufacturing technologies, is widely investigated to fabricate metal parts. In SLM, parts are manufactured directly from powders in a layer-by-layer fashion; SLM also provides several advantages, such as production of complex parts with high three-dimensional accuracy, compared with other additive manufacturing technologies. Therefore, SLM can be applied in aeronautics, astronautics, medicine, and die and mould industry. However, this technique differs from traditional methods, such as casting and forging; for instance, the former greatly differs in terms of microstructure and properties of products. This paper summarizes relevant studies on metal material fabrication through SLM. Based on a work completed in Huazhong Univ. Sci Tech., Rapid Manuf. Center (HUST-RMC) and compared with characteristics described in other reported studies, microstructure, properties, dimensional accuracy, and application of SLM are presented.

关键词： selective laser melting microstructure performance application

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Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

《机械工程前沿（英文）》 2023年第18卷第2期 doi: 10.1007/s11465-022-0737-8

摘要： Selective laser melting (SLM) is a unique additive manufacturing (AM) category that can be used to manufacture mechanical parts. It has been widely used in aerospace and automotive using metal or alloy powder. The build orientation is crucial in AM because it affects the as-built part, including its part accuracy, surface roughness, support structure, and build time and cost. A mechanical part is usually composed of multiple surface features. The surface features carry the production and design knowledge, which can be utilized in SLM fabrication. This study proposes a method to determine the build orientation of multi-feature mechanical parts (MFMPs) in SLM. First, the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives. Second, the estimation models of involved optimization objectives are established, and a set of alternative build orientations (ABOs) is further obtained by many-objective optimization. Lastly, a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs. The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process. Two case studies are reported to validate the proposed method with numerical results, and the effectiveness comparison is presented. Physical manufacturing is conducted to prove the performance of the proposed method. The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82, 10.84, and 10.62 μm, respectively. The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.

关键词： selective laser melting (SLM) build orientation determination multi-feature mechanical part (MFMP) fuzzy analytical hierarchy process multi-objective decision making (MODM)

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Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

《化学科学与工程前沿（英文）》 2009年第3卷第3期页码 255-264 doi: 10.1007/s11705-009-0008-9

摘要： The spherulites of the short carbon fiber(SCF)/poly (trimethylene terephthalate) (PTT) composites formed in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content. However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180°C to 230°C, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Discontinuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room temperature at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

关键词： poly(trimethylene terephthalate) short carbon fiber banded spherulites crack

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Research on low emission MSW gasification and melting system

XIAO Gang, NI Mingjiang, CHI Yong, JIN Yuqi, ZHANG Jiaquan, MIAO Qi, CEN Kefa

《环境科学与工程前沿（英文）》 2007年第1卷第4期页码 498-503 doi: 10.1007/s11783-007-0080-7

摘要： In order to eliminate secondary pollution caused by municipal solid waste (MSW) incineration, a MSW gasification and melting process is proposed. The process is expected to reduce the emission of pollutants, especially heavy-meta

关键词： gasification incineration municipal heavy-meta secondary

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Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

《机械工程前沿（英文）》 2010年第5卷第2期页码 143-148 doi: 10.1007/s11465-010-0006-0

摘要： Selective laser sintering (SLS) of a two-component metal powder layer on the top of multiple sintered layers by a moving Gaussian laser beam is modeled. The loose metal powder layer is composed of a powder mixture with significantly different melting points. The physical model that accounts the shrinkage induced by melting is described by using a temperature-transforming model. The effects of the porosity and the thickness of the atop loose powder layer with different numbers of the existing sintered metal powder layers below on the sintering process are numerically investigated. The present work will provide a better understanding to simulate much more complicated three-dimensional SLS process.

关键词： laser sintering melting solidification heat transfer

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选区激光熔化纯钨——粉末粒径对激光吸收的影响和扫描轨迹形成机理研究 Article

章佳窈, 顾冬冬, 杨莹, 张红梅, 陈洪宇, 戴冬华, 林开杰

《工程（英文）》 2019年第5卷第4期页码 736-745 doi: 10.1016/j.eng.2019.07.003

摘要：

本文建立了基于线迹追踪的三维激光吸收模型，用于描述选区激光熔化（SLM）成形纯钨粉末时激光束与粉末层的相互作用，研究了粉末粒径大小对粉末激光吸收率和吸收行为的影响。本文给出了激光吸收率、粉层吸收辐照度及其分布、激光扫描轨迹的表面形貌和几何特征（如接触角、宽度和高度，以及重熔深度）之间的内在关系。模拟结果表明，粉末层的吸收率大大超过单一的粉末颗粒或致密平板材料的吸收率。随着粉末粒径增加，粉末层吸收的激光能量减少。当粒径为5 μm时，纯钨粉末层的吸收率最大达到0.6030。激光辐照度在粉床颗粒表面的分布与粒径大小、方位角和粉末在基板上的位置有关。当粒径从5 μm增加到45 μm时，粉末层中的最大辐照度从1.117 × 10^–3 W·μm^–2降低到0.85 × 10^–3 W·μm^–2，并且位于中心辐照区域的辐照度分布轮廓逐渐收缩。对SLM纯钨扫描轨迹的表面形貌和横截面几何特征进行了研究，结果验证了模拟的粉末激光吸收行为。该工作对线迹追踪模型预测SLM扫描轨迹润湿性和铺展性的应用提供了科学依据，从而更好地获得优异的激光成形性能。

关键词：选区激光熔化钨线迹追踪模型吸收率激光扫描轨迹

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结构参数对激光熔化制造的2D五模结构泊松比和压缩模量的影响 Article

张磊, 宋波, 刘瑞杰, 赵爱国, 张金良, 卓林蓉, 汤桂平, 史玉升

《工程（英文）》 2020年第6卷第1期页码 56-67 doi: 10.1016/j.eng.2019.06.009

摘要：为了验证模拟的力学性能结果，采用选择性激光熔化（selective laser melting, SLM）方法制备了Ti-6Al-4V合金的五模结构试样，并对其力学性能（泊松比和弹性模量）进行了实验研究

关键词：超材料五模材料有限元分析激光选区熔化

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微观选择性激光熔化技术发展的现状及未来展望 Review

Balasubramanian Nagarajan, Zhiheng Hu, Xu Song, Wei Zhai, Jun Wei

《工程（英文）》 2019年第5卷第4期页码 702-720 doi: 10.1016/j.eng.2019.07.002

摘要：

增材制造（AM）能将各种材料制成形状复杂的部件，因此在制造业中越来越受到青睐。选择性激光熔化（SLM）是一种常见的AM技术，它基于粉床熔融法（PBF）来处理金属，但目前只专注于大中型元件的制作。本文综述了微型金属材料SLM的研究现状。与通常用于微观AM的直接写入技术相比，微观SLM由于许多因素而更加具有吸引力，包括更快的周期时间、流程简单性和材料通用性。此外，本文综合评价了利用SLM和选择性激光烧结（SLS）制造微尺度零件的各种研究工作和商业系统，不仅从微观尺度上找出了SLM存在的问题，包括粉末重涂、激光光学和粉末粒度等，还详细阐述了SLM未来的发展方向。文章详细回顾了粉床技术中现有的粉末重涂方法，并描述了在AM领域实施干粉分配方法的新进展。对AM部件的一些二次整理技术进行了回顾，重点介绍了细微加工特征的应用以及与微观SLM系统的结合。

关键词：增材制造选择性激光熔化微细加工混合处理粉床重涂

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双金属电子束选区熔化的硬件开发与成形实验 Article

郭超, 葛文君, 林峰

《工程（英文）》 2015年第1卷第1期页码 124-130 doi: 10.15302/J-ENG-2015013

摘要：

电子束选区熔化（EBSM）是一种利用电子束扫描、熔化金属粉末逐层制造三维实体零件的增材制造技术。近年来，EBSM已经成功应用于多种材料的增材制造。现有EBSM工艺方面的研究主要聚焦于单种材料的成形，本研究提出一种能够利用两种粉末材料成形梯度结构的EBSM工艺，提出基于振动的粉末供给方法，并实现了两种粉末材料独立供给并混合。利用Ti6Al4V和Ti47Al2Cr2Nb两种材料进行成形。Ti6Al4V在室温下有很好的强度与塑性，而Ti47Al2Cr2Nb在高温下性能优良，但有很大的室温脆性。本研究提出的双金属EBSM工艺成功制备了Ti6Al4V/Ti47Al2Cr2Nb梯度结构，并利用光学显微镜、扫描电子显微镜、电子微探针分析等方法研究了该梯度结构的微观组织和化学成分。结果显示，梯度结构的截面厚度约为300 μm，没有裂纹，化学成分在界面处呈阶梯式变化。

关键词：增材制造电子束选区熔化梯度材料钛合金钛铝合金