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Hyper-crosslinked Conjugated Microporous Polymers with Increased Micropores Promotes Confining Polymerization for Electromagnetic Absorption Application

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Chinese Journal of Polymer Science 2023年第8期41卷 1305-1316,I0011页

作者： Hao Chen Fang-Yuan Chu Hai-Yan Zhuang Lu Wang zhi-Min Ye Wei Dong zhi-peng xie A-Ming xie School of Mechanical Engineering Nanjing University of Science&TechnologyNanjing 210094China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research Institute(LSMRI)Xiamen 361100China School of Chemistry and Chemical Engineering Nanjing University of Science&TechnologyNanjing 210094China

Conjugated microporous polymers have excellent skeleton structures but poor electrical conductivity limits their applications in microwave *** solve this problem,a strategy of molecular expansion and confining polymerization is proposed in this work to synthesize conductive hyper-crosslinked conjugated microporous *** topology of the conjugated microporous polymer is changed into a three-dimensional skeleton structure with high specific surface area by using molecular expansion technique,and the controlled growth of polypyrrole in the channel constructs a unique network *** balance of excellent composite backbone structure,proper conductivity,attenuation capability and impedance matching enable the material to exhibit electromagnetic wave absorption *** a result,with low filler loading of 10 wt%,a strongest reflection loss of-52.68 d B and a maximum effective bandwidth of 5.76 ***,CST simulations of the radar scattering cross section have been carried out to verify the excellent material *** study provides new concepts for new conductive polymers and broadens the application of hyper-crosslinked conjugated microporous polymer in the field of electromagnetic wave absorption.

关键词： Hyper-crosslinked conjugated microporous polymer Electromagnetic wave absorbing Molecular expansion Polypyrrole

Injection molding of ultra-fine Si_3N_4 powder for gas-pressure sintering

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International Journal of Minerals,Metallurgy and Materials 2015年第6期22卷 654-659页

作者： Xian-feng Yang Jiang-hong Yang xie-wen Xu Qi-cheng Liu zhi-peng xie Wei Liu College of Physics and Electronics Science Changsha University of Science and Technology School of Materials Science and Engineering Tsinghua University

The ceramic injection molding technique was used in the gas-pressure sintering of ultra-fine Si3N4 powder. The feedstock＇s flowability, debinding rate, defect evolution, and microstructural evolution during production were explored. The results show that the solid volume loading of less than 50vol% and the surfactant mass fraction of 6wt% result in a perfect flowability of feedstock; this feedstock is suitable for injection molding. When the debinding time is 8 h at 40°C, approximately 50% of the wax can be solvent debinded. Defects detected during the preparation are traced to improper injection parameters, mold design, debinding parameters, residual stress, or inhomogeneous composition distribution in the green body. The bulk density, Vickers hardness, and fracture toughness of the gas-pressure-sintered Si3N4 ceramic reach 3.2 g/cm^3, 16.5 GPa, and 7.2 MPa·m^1/2, respectively.

关键词： ceramic materials silicon nitride injection molding sintering near net shaping

A strategy to obtain a high-density and high-strength zirconia ceramic via ceramic injection molding by the modification of oleic acid

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International Journal of Minerals,Metallurgy and Materials 2017年第6期24卷 718-725页

作者： Jia-xin Wen Tian-bin Zhu zhi-peng xie Wen-bin Cao Wei Liu School of Materials Science and Engineering University of Science and Technology Beijing Sate Key Laboratory of New Ceramics and Fine Processing Department of Materials Science and Engineering Tsinghua University School of Electromechanical Engineering Guangdong University of Technology

Despite its unique high efficiency and good environmental compatibility, the water-soluble binder system still encounters problems achieving a desired sintered part via ceramic injection molding because of the poor compatibility and the powder-binder segregation between ceramic powders and binders. The objective of this study was to obtain a sintered part with excellent properties by introducing a small quantity of oleic acid to the surface of zirconia powders before the mixing process. As opposed to many previous investigations that focused only on the rheological behavior and modification mechanism, the sintering behavior and densification process were systematically investigated in this study. With the modified powders, debound parts with a more homogeneous and smaller pore size distribution were fabricated. Also, a higher density and greater flexural strength were achieved in the sintered parts fabricated using the modified powders.

关键词： ceramic materials zirconia injection molding oleic acid sintering

Sintering kinetics involving grain growth and densification of Mg-PSZ nanopowders

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Journal of Iron and Steel Research International 2022年第7期29卷 1138-1144页

作者： Yi-ming She Jie-fu Lang Di An Chao-wei Si Xu-dong Luo zhi-peng xie Jie-gang You School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina Institute of Advanced Structures Beijing Institute of TechnologyBeijing 100081China State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Sintering kinetics have been found to be effective in judging the evolution of *** using magnesium oxide-partially stabilized zirconia(Mg-PSZ)powder prepared by co-precipitation as raw materials,the evolution of densification and grain growth for Mg-PSZ ceramics were *** results indicated that the densification of samples was mainly controlled by grain boundary diffusion in intermediate sintering *** the sintering process,the grain growth mechanisms included normal grain growth,abnormal grain growth and solid solution drag-controlled grain ***,the apparent activation energy for grain growth of Mg-PSZ ceramics is lower than that of ZrO_(2)–Y_(2)O_(3)ceramics in the solid solution drag-controlled grain grow process,which will cause grain to grow *** sintering kinetics and microstructure of Mg-PSZ ceramics were studied,and the kinetic equation of grain growth at different temperatures was *** results show that the strength difference between Mg-PSZ and yttrium oxide-stabilized zirconia is closely related to the easy grain growth of Mg-PSZ ceramics.

关键词： Magnesium oxide-partially stabilized zirconia Sintering kinetics Grain growth mechanism Densification mechanism Sizing nozzle

基于遥爪型大分子交联剂的动态化学交联水凝胶的黏弹性质

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功能高分子学报 2018年第3期31卷 241-247页

作者：叶志鹏谢曼青谢家礼赵传壮宁波大学材料科学与化学工程学院宁波市特种高分子材料重点实验室浙江宁波315211

以壳聚糖为主链,以双端苯醛基聚乙二醇(DF-PEG)为交联剂,以希夫碱为动态交联键制备了动态化学交联水凝胶,通过改变大分子交联剂的分子量和浓度调控凝胶网络结构。以旋转流变仪的动态频率扫描和稳态剪切为主要手段,研究了凝胶结构对凝胶... 详细信息

以壳聚糖为主链,以双端苯醛基聚乙二醇(DF-PEG)为交联剂,以希夫碱为动态交联键制备了动态化学交联水凝胶,通过改变大分子交联剂的分子量和浓度调控凝胶网络结构。以旋转流变仪的动态频率扫描和稳态剪切为主要手段,研究了凝胶结构对凝胶模量、松弛时间、剪切增稠程度的影响。结果表明:DF-PEG的分子量和浓度会影响凝胶网络内弹性活性链的密度从而影响模量、松弛时间,而凝胶剪切增稠程度与弹性活性链密度密切相关。

关键词：动态化学交联凝胶遥爪聚合物线性流变非线性流变剪切增稠

Multi-layer multi-pass friction rolling additive manufacturing of Al alloy:Toward complex large-scale high-performance components

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 425-438页

作者： Haibin Liu Run Hou Chenghao Wu Ruishan xie Shujun Chen College of Mechanical&Energy Engineering Beijing University of TechnologyBeijing 100124China Chongqing Research Institute of Beijing University of Technology Chongqing 401121China

At present,the emerging solid-phase friction-based additive manufacturing technology,including friction rolling additive man-ufacturing(FRAM),can only manufacture simple single-pass *** this study,multi-layer multi-pass FRAM-deposited alumin-um alloy samples were successfully prepared using a non-shoulder tool *** material flow behavior and microstructure of the over-lapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum *** results showed that a mechanical interlocking structure was formed between the adjacent layers and the adja-cent passes in the overlapped center *** friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone,which made the recrystallization degree in the left and right edge zones of the over-lapped zone the highest,followed by the overlapped center zone and the non-overlapped *** tensile strength of the overlapped zone exceeded 90%of that of the single-pass deposition *** is proved that although there are uneven grooves on the surface of the over-lapping area during multi-layer and multi-pass deposition,they can be filled by the flow of materials during the deposition of the next lay-er,thus ensuring the dense microstructure and excellent mechanical properties of the overlapping *** multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.

关键词： aluminum alloy additive manufacturing solid-state friction stir welding multi-layer multi-pass

Superhydrophobic and corrosion-resistant siloxane-modified MgAl-LDHs coatings on magnesium alloy prepared under mild conditions

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 450-463页

作者： Wenxi Zhang Zhangzelong Zhuo Dan Xu Liang Wu zhihui xie Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province College of Chemistry and Chemical EngineeringChina West Normal UniversityNanchong 637002China College of Materials Science and Engineering/National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China

We have developed a superhydrophobic and corrosion-resistant LDH-W/PFDTMS composite coating on the surface of Mg *** composite comprised a tungstate-intercalated(LDH-W)underlayer that was grown at low temperature(relative to hydrothermal reaction conditions)under atmospheric pressure and an outer polysiloxane layer created from a solution containing perfluorodecyltrimethoxysilane(PFDTMS)using a simple immersion *** successful intercalation of tungstate into the LDH phase and the following formation of the polysiloxane layer were confirmed through X-ray diffraction(XRD),Fourier transform infrared(FTIR)spectroscopy,and X-ray photoelectron spectroscopy(XPS).The corrosion resistance of the LDH-W film,both before and after the PFDTMS modification,was evaluated using electrochemical impedance spectroscopy(EIS),Tafel curves,and immersion *** results showed that Mg coated with LDH-W/PFDTMS exhibited significantly enhanced corrosion protection compared to the unmodified LDHW film,with no apparent signs of corrosion after exposure to 3.5wt%NaCl solution for 15 ***,the LDH-W/PFDTMS coating demonstrated superior superhydrophobicity and self-cleaning properties against water and several common beverages,as confirmed by static contact angle and water-repellency *** results offer valuable insights into preparing superhydrophobic and corrosion-resistant LDH-based composite coatings on Mg alloy surfaces under relatively mild reaction conditions.

关键词： Mg alloy corrosion coating layered double hydroxide

Unraveling the significance of cobalt on transformation kinetics,crystallography and impact toughness in high-strength steels

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 380-390页

作者： Yishuang Yu Jingxiao Zhao Xuelin Wang Hui Guo Zhenjia xie Chengjia Shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic *** results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without ***,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to *** improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant ***,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant *** findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.

关键词： high-strength steel cobalt transformation kinetics crystallography impact toughness

Thermodynamic Study on the Solubility Properties of Guangxi Artemisinin Derivatives

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Thermodynamic Study on the Solubility Properties of Guangxi ...