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Journal of Magnesium and Alloys 2022年第5期10卷 1296-1310页

作者： Kai Xiang Kuah Daniel J.Blackwood Wee Kit Ong Mojtaba Salehi Hang Li Seet mui ling sharon nai Sudesh Wijesinghe Department of Materials Science&Engineering National University of Singapore9 Engineering Drive 1117575 Singapore Reliability and Characterisation Unit Singapore Institute of Manufacturing Technology(SIMTech)Agency forScienceTechnology and Research(A^(∗)STAR)73 Nanyang Drive637662 Singapore Additive Manufacturing Group Singapore Institute of Manufacturing Technology(SIMTech)Agency forScienceTechnology and Research(A^(∗)STAR)73 Nanyang Drive637662 Singapore

Binder jet printing(BJP)is a state-of-the-art additive manufacturing technique for producing porous magnesium *** MgZn-Zr based BJP samples were assessed for corrosion performance in simulated body fluids by electrochemical and hydrogen evolution *** corrosion rates of the BJP specimens were significantly higher than solid controls,even after accounting for their larger surface areas,suggesting that the BJP microstructure is detrimental to corrosion performance.X-ray computed tomography revealed nonuniform corrosion within the porous structure,with corrosion products forming on the pore *** the pores with hydroxyapatite or polymers greatly improved the corrosion resistance of the BJP samples.

关键词： Magnesium Additive manufacturing Binder jetting Porous Corrosion Biodegradability

Additively manufactured heterogeneously porous metallic bone with biostructural functions and bone-like mechanical properties

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Journal of Materials Science & Technology 2021年第3期62卷 173-179页

作者： Pan Wang Xinwei Li Shumin Luo mui ling sharon nai Jun Ding Jun Wei Singapore Institute of Manufacturing Technology A*STAR73 Nanyang Drive637662Singapore Department of Materials Science and Engineering National University of Singapore117576Singapore

A compatible artificialbone impla nt requires large pores for enhanced nutrients transports,small pores to allow cell seeding and bone-like mechanical properties to avoid stress ***,we report novel improved gyroid lattices with millimetre-scaled gyroid wall spacings and micrometre-scaled additional pores on the *** are successfully fabricated by electron beam melting using Ti-6 Al-4 V to high part qualities while exhibiting bone-like mechanical properties with a range of Young's modulus of 8-15 GPa and strength of 150-250 *** improved design also eliminates brittle failure by allowing the structure to deform more stably.

关键词： Microlattice Metallic bone Implant Electron beam melting 3D printing

Additive manufacturing of high-entropy alloys by thermophysical calculations and in situ alloying

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Journal of Materials Science & Technology 2021年第35期94卷 53-66页

作者： Mehmet Cagirici Pan Wang Fern Lan Ng mui ling sharon nai Jun Ding Jun Wei Singapore Institute of Manufacturing Technology 73 Nanyang Drive637662Singapore Department of Materials Science and Engineering National University of Singapore117576Singapore

Electron beam melting(EBM)is a promising technology to manufacture various alloys with outstanding properties;however,the number of available alloys is *** propose in situ alloying to accelerate the development of advanced and novel alloys,based on thermophysical calculations and CALPHAD approach,during the EBM *** demonstrate our concept through the design and fabrication of high entropy alloys(HEAs).Three CoCrFeNiMn-xTi(x=0.18,0.50,2.00,in molar%)HEAs are ***-built HEAs achieve a homogeneous distribution of elements while forming multiphase alloys resulted from the hot powder *** topological structures formed by secondary phases contribute to an increase in the hardness of EBM-built HEAs up to 900 *** alloy design,a systematic analysis on Co Cr Fe Ni Mn-0.18 Ti HEA elucidates the microstructural evolution in *** findings provide a deep understanding of in situ alloying and pave the way to develop new alloys specific to the EBM process.

关键词： 3D printing Cost reduction Electron beam melting High entropy alloy Mechanical properties Phase prediction

Characteristics of Inconel Powders for Powder-Bed Additive Manufacturing

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Engineering 2017年第5期3卷 695-700页

作者： Quy Bau Nguyen mui ling sharon nai Zhiguang Zhu Chen-Nan Sun Jun wei Wei Zhou Singapore Institute of Manufacturing Technology Singapore 637662 Singapore School of Mechanical and Aerospace Engineering Nanyang Technological UniVersity Singapore 639798 Singapore

本研究中使用不同的粉末表征技术对铬镍铁合金的原始粉末和回收粉末在粉末床增材制造(AM)上的流动特性、行为特征进行研究。结果发现,选择性激光熔化(SLM)工艺的粒径分布(PSD)范围通常在15～63μm之间。原始的铬镍铁合粉末的流量约为28 ... 详细信息

本研究中使用不同的粉末表征技术对铬镍铁合金的原始粉末和回收粉末在粉末床增材制造(AM)上的流动特性、行为特征进行研究。结果发现,选择性激光熔化(SLM)工艺的粒径分布(PSD)范围通常在15～63μm之间。原始的铬镍铁合粉末的流量约为28 s·(50 g)–1,组装密度是60%。流变测试结果表明,原始粉末与回收粉末相比具有更好的流动性。讨论了两种粉末之间的相互关系。运用铬镍铁合金粉末已经成功打印出了螺旋桨。实验结果表明铬镍铁合金粉末适用于增材制造(AM),本研究为生产增材制造粉末提供参考。

关键词：增材制造粉末特征气体雾化微观结构铬镍铁合金

Characterization of nanoparticle mixed 316L powder for additive manufacturing

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Journal of Materials Science & Technology 2020年第12期47卷 162-168页

作者： Wengang Zhai Wei Zhou sharon mui ling nai Jun Wei School of Mechanical and Aerospace Engineering Nanyang Technological University50 Nanyang Avenue639798Singapore Singapore Institute of Manufacturing Technology 73 Nanyang Drive637662Singapore

Nanoparticles reinforced steels have many advantaged mechanical *** manufacturing offers a new method for fabricating nanoparticles reinforced high performance metal *** this work,we report the application of low energy ball milling in mixing nanoparticles and micron 316 L *** this method,0.3 and 1.0 wt% Y2 O3 nanoparticles can be uniformly distributed on the surface of 316 L powder with the parameters of ball-to-powder ratio at 1:1,speed at 90 rpm and 7 h of *** matrix 316 L powders remain spherical in shape after the mixing *** the meantime,the effect of low energy ball milling and the addition of Y2 O3 nanoparticles on the powder characteristics(flowability,apparent density and tap density) are also *** show that the process of low energy ball milling itself can slightly decrease the flowability and apparent density of the 316 L *** addition of 0.3 and 1.0 wt% Y2 O3 nanoparticles can also decrease the flowability,the tap density and the apparent density compared with the original 316 L *** of these changes result from the rough surface of the mixed powder produced by ball milling and the addition of Y2 O3 *** powder’s rough surface can increase the coefficient of friction of *** mixture of 316 L powder and Y2 O3 nanoparticles can be successfully used for selective laser melting(SLM).The relative density of SLM 316 L-Y2 O3 is measured at 99.5%.However,Y2 O3 agglomerations were observed which is due to the poor wettability between 316 L and Y2 O3.

关键词： Powder mixing Powder characterization Flowability Apparent density Tap density Additive manufacturing

Root exclusion methods for partitioning of soil respiration:Review and methodological considerations

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Pedosphere 2023年第5期33卷 683-699页

作者： Mei-Yee CHIN sharon Yu ling LAU Frazer MIDOT mui Sie JEE Mei Lieng LO Faustina E.SANGOK Lulie MELling Sarawak Tropical Peat Research Institute Lot 6035Kuching-Kota Samarahan ExpresswayKota SamarahanSarawak 94300Malaysia

Soil respiration is a vital process in all terrestrial ecosystems,through which the soil releases carbon dioxide(CO_(2))into the atmosphere at an estimated annual rate of 68–101 Pg carbon,making it the second highest terrestrial contributor to carbon *** soil respiration consists of autotrophic and heterotrophic constituents,methods for accurately determining the contribution of each constituent to the total soil respiration are critical for understanding their differential responses to environmental factors and aiding the reduction of CO_(2)*** to its low cost and simplicity,the root exclusion(RE)technique,combined with manual chamber measurements,is frequently used in field studies of soil respiration ***,RE treatments alter the soil environment,leading to potential bias in respiration *** review aims to elucidate the current understanding of RE,i.e.,trenching(Tr)and deep collar(DC)insertion techniques,by examining soil respiration partitioning studies performed in several ***,we discuss methodological considerations when using RE and the combinations of RE with stable isotopic and modeling ***,future research directions for improving the Tr and DC insertion methods in RE are suggested.

关键词： autotrophic respiration deep collar insertion heterotrophic respiration microbial respiration root trenching soil microbial community soil respirationcomponent

Investigation on surface integrity of electron beam melted Ti-6Al-4 V by precision grinding and electropolishing

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Chinese Journal of Aeronautics 2021年第12期34卷 28-38页

作者： Jiang GUO Min Hao GOH Pan WANG Rui HUANG Xiaohua LEE Bin WANG sharon mui ling nai Jun WEI Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China Ningbo Institute of Dalian University of Technology Ningbo 315016China Singapore Institute of Manufacturing Technology Singapore 637662Singapore Harbin Institute of Technology Shenzhen 518055China

Electron beam melting(EBM),as an excellent Additive Manufacturing(AM)technology,enables the printing of Ti-6Al-4V alloy for a wide range of applications such as aerospace and biomechanical *** improves functionality and integrity of components and negates complexities in assembly ***,due to the poor surface and sub-surface integrity represented by the rough surface finish and low dimensional accuracy,achieving a favorable surface condition is quite ***,post processing becomes essential for these electron beam melted(EBM-ed)Ti-6Al-4V *** the most common technique to improve such parts,milling of Ti-6Al-4V alloy is very challenging and resulting tool wear issues,due to its unique material ***,this paper presents a comprehensive study on the surface integrity of EBM-ed Ti-6Al-4V parts processed by precision grinding and electropolishing,aiming to qualitatively and quantitatively clarify the interrelation between process parameters and processed surface *** surface and subsurface characteristics such as profile accuracy,surface roughness,microstructure,defective layer and residual stress before and after post processing were compared and *** results show that by precision grinding,the profile accuracy was improved from over 300μm PV to 7μm PV,while surface roughness(R_(a))was reduced from 30μm to about 2μ*** layer with partially melt particles was removed,but introduced a deformed subsurface layer with more residual *** by applying electropolishing,the residual stress was released and the deformed layer was *** addition,Ra was further reduced to 0.65μ*** research can serve as a reference for the integration of post machining processes with AM.

关键词： Additive Manufacturing(AM) Electron Beam Melting(EBM) Electropolishing Grinding Surface integrity Ti-6Al-4V alloy