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Effect of chromium content on microstructure and corrosion behavior of W-Cr-C coatings prepared on tungsten substrate

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Frontiers of Materials Science 2015年第1期9卷 77-84页

作者： Yan jiang Jun-feng yang Qian-feng FANG Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China

W-Cr-C coatings with different chromium contents （0-3wt.%） were fabricated on the tungsten substrates by spark plasma sintering （SPS） method from the graphite and chromium mixed powders. SEM and XRD were exploited to analyze the effect of Cr contents on the microstructure of coatings. It was found that the abnormal hollow WC grains disappeared with addition of Cr less than 2%, and the microstructures were largely refined and densified. With further increase of Cr addition, the grains changed slightly but the densificaUon was reduced. The most dense coating was achieved at I wt.% Cr. Corrosion behavior of the W-Cr-C coatings were investigated by impedance spectrum and potentiodynamic polarization tests. Results suggested that the W-1Cr-C coated W sample exhibited the lowest corrosion current density and highest corrosion potential due to the most densified microstructure, indicating that the addition of Cr at 1 wt.% was optimal for WC coating against corrosion.

关键词： W-Cr-C coating spark plasma sintering (SPS) corrosion resistance electrochemical measurement

烧结温度对SPS制备Ti_(2)AlNb组织与拉伸性能的影响

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稀有金属与硬质合金 2024年第3期52卷 60-65页

作者：王恒荣姜凤阳思芳杜予晅王俊勃刘江南刘建江西安工程大学材料工程学院陕西西安710048 西部超导材料科技股份有限公司陕西西安710018

采用高能球磨和放电等离子烧结技术制备了Ti_(2)AlNb合金,利用SEM、EDS和XRD对合金显微组织及物相结构进行表征,利用万能拉伸试验机测试合金室温抗拉强度,并观察其断口形貌,以此分析不同烧结温度对Ti_(2)AlNb合金组织及拉伸性能的影响... 详细信息

采用高能球磨和放电等离子烧结技术制备了Ti_(2)AlNb合金,利用SEM、EDS和XRD对合金显微组织及物相结构进行表征,利用万能拉伸试验机测试合金室温抗拉强度,并观察其断口形貌,以此分析不同烧结温度对Ti_(2)AlNb合金组织及拉伸性能的影响。结果表明,不同烧结温度下Ti_(2)AlNb合金均由O相、B2相及α_(2)相组成;O相形态随烧结温度变化而发生改变,在950℃烧结时,O相呈Rim-O相形态,1 000℃烧结时呈针状O相,1 050℃与1 100℃烧结时呈板条状O相。在烧结温度1 000℃、保温时间90 min以及压强50 MPa的条件下,Ti_(2)AlNb合金的室温抗拉强度可达198 MPa,室温拉伸后的断裂类型是以解理断裂为主的脆性断裂。

关键词： Ti_(2)AlNb SPS 烧结温度室温拉伸性能

二次烧结温度对放电等离子烧结制备Ti_(2)AlNb合金显微组织和力学性能的影响

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稀有金属与硬质合金 2024年第4期52卷 54-58,89页

作者：陈金坤姜凤阳思芳杜予晅王俊勃刘江南王恒荣西安工程大学材料工程学院陕西西安710048 西部超导材料科技股份有限公司陕西西安710018

采用高能球磨法和放电等离子烧结(SPS)技术制备了Ti_(2)AlNb合金;利用X射线衍射仪(XRD)、扫描电镜(SEM)和万能拉伸试验机研究了二次烧结温度对合金显微组织和力学性能的影响。结果表明:不同二次烧结温度所制备的Ti_(2)AlNb合金组织均由B... 详细信息

采用高能球磨法和放电等离子烧结(SPS)技术制备了Ti_(2)AlNb合金;利用X射线衍射仪(XRD)、扫描电镜(SEM)和万能拉伸试验机研究了二次烧结温度对合金显微组织和力学性能的影响。结果表明:不同二次烧结温度所制备的Ti_(2)AlNb合金组织均由B2相、等轴状α_(2)相和针状O相组成。二次烧结温度在900~950℃范围内时,针状O相呈第二相在B2基体相内部析出,等轴状α_(2)相团聚在B2基体相之间;二次烧结温度在1000~1100℃范围内时,等轴状α_(2)相分布不再集中,数量逐渐减少。二次烧结温度为1000℃所制备的Ti_(2)AlNb合金拥有良好的力学性能,室温抗拉强度达到309 MPa,维氏硬度可达466.5 HV。

关键词： Ti_(2)AlNb 放电等离子烧结二次烧结温度显微组织室温抗拉强度

Synthesis of a new aromatic diacid containing pyridine ring and related polybenzimidazole

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Chinese Chemical Letters 2010年第8期21卷 976-978页

作者： Tao Ma Yan feng Li Shu jiang Zhang feng Chun yang Chen Liang Gong Jiu jiang Zhao College of Chemistry and Chemical Engineering State Key Laboratory of Applied Organic Chemistry Institute of Biochemical Engineering & Environmental TechnologyLanzhou UniversityLanzhou 730000China

A new aromatic diacid monomer containing pyridine unit,4-phenyl-2,6-bis[4-（4-carboxyphenoxy） phenyl]pyridine 3,was successfully synthesized in three steps,starting from *** corresponding pyridine-containing polybenzimidazole was prepared via polycondensation of 3 with tetraaminodiphenyl ether（TADE） in poly（phosphoric acid）（PPA）.The resulting polybenzimidazole exhibits excellent solubility,good thermal stabilities and high thermal resistance.

关键词： Polybenzimidazoles Pyridine-containing diacid monomer Synthesis Thermal stabilities

EPDM增韧PP/HDPE共混物的组织及增韧机制

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塑料科技 2024年第5期52卷 23-27页

作者：付明宇姜凤阳俞慧冀迪惠海峰陈明情弓合兴王俊勃西安工程大学材料工程学院陕西西安710048 福建冠泓工业有限公司福建石狮362700

为提高聚丙烯(PP)增韧效率并研究其增韧机制,以PP/高密度聚乙烯(HDPE)共混物为基体,三元乙丙橡胶(EPDM)为增韧改性剂,通过熔融共混法制备PP/HDPE/EPDM共混物。结果表明:EPDM与HDPE形成核壳结构分散在基体中,并增强了与基体之间相互作用... 详细信息

为提高聚丙烯(PP)增韧效率并研究其增韧机制,以PP/高密度聚乙烯(HDPE)共混物为基体,三元乙丙橡胶(EPDM)为增韧改性剂,通过熔融共混法制备PP/HDPE/EPDM共混物。结果表明:EPDM与HDPE形成核壳结构分散在基体中,并增强了与基体之间相互作用力。EPDM对PP的结晶具有促进作用,但对HDPE的结晶起到抑制作用,进而细化核壳结构分散相。随着EPDM含量的增加(4%~12%),PP/HDPE/EPDM共混物抗冲击强度增强,EPDM能够在增韧PP的同时延缓PP拉伸强度的快速下降。当EPDM含量为16%时,共混物的抗冲击强度达到11.18 kJ/m2,较PP/HDPE的抗冲击强度分别提高了158%。PP/HDPE/EPDM共混物的增韧机制为EPDM壳和HDPE核结构的空穴化作用,从而提升其能量的吸收。

关键词：聚丙烯高密度聚乙烯三元乙丙橡胶抗冲击强度增韧机制

聚丙烯/聚二甲基硅氧烷防尘复合材料的制备及性能

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塑料科技 2024年第6期52卷 61-66页

作者：周尧姜凤阳车秋凌思芳周亮刘松涛王俊勃西安工程大学材料工程学院陕西西安710048 安踏(中国)有限公司福建晋江362212 陕西鼎新汇智功能材料科技有限公司陕西西安710048

为提升聚合物防尘性能,以聚丙烯(PP)为基体,聚二甲基硅氧烷(PDMS)和内添加型抗静电剂(JN-MN)为填料,通过熔融共混法制备聚丙烯/聚二甲基硅氧烷(PP/PDMS)和聚丙烯/聚二甲基硅氧烷/抗静电剂(PP/PDMS/K)防尘复合材料。采用傅里叶红外分析... 详细信息

为提升聚合物防尘性能,以聚丙烯(PP)为基体,聚二甲基硅氧烷(PDMS)和内添加型抗静电剂(JN-MN)为填料,通过熔融共混法制备聚丙烯/聚二甲基硅氧烷(PP/PDMS)和聚丙烯/聚二甲基硅氧烷/抗静电剂(PP/PDMS/K)防尘复合材料。采用傅里叶红外分析仪、接触角测试仪、场发射扫描电镜、万能试验机等测试复合材料,探究不同含量PDMS和抗静电剂对复合材料防尘性能、表面电阻率、结晶性能、力学性能的影响。结果表明:随着PDMS含量增加,PP/PDMS复合材料的疏水性能逐渐增强。当PDMS含量为8%时,复合材料的水接触角提升27.7%,其表面能降低7.13%。当抗静电剂含量增加,复合材料的结晶度降低,表面电阻相较于纯PP降低了5个数量级。添加3%抗静电剂已达到饱和,PP/PDMS/K复合材料除尘率提高至88.93%,拉伸强度和弯曲强度下降,但冲击韧性仍保持较高水平。

关键词：聚丙烯聚二甲基硅氧烷抗静电防尘

Fabrication of AZ31/Mg3Y Composites with Excellent Strength and Plasticity via Accumulated Rolling Bonding and Diffusion Annealing

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 339-352页

作者： yang feng Wenhuan Chen Zheng Xu Weijun He Bin jiang Fusheng Pan College of Materials Science and Engineering Chongqing UniversityChongqing400044China International Joint Laboratory for Light Alloys(Ministry of Education) Chongqing UniversityChongqing400044China

AZ31/Mg3Y composites with a layer thickness of 100-200μm were fabricated by accumulated rolling bonding(ARB),which was followed by diffusion annealing at 300℃ for 0-32 *** interface layer,containing numerous Al-Y precipitates,is formed in the Mg3Y layer that is adjacent to the interface as a result of Al diffusing from the AZ31 layers into the Mg3Y *** thickness of the interface layer gets increased and more precipitates are formed in the interface layer with the extension of the annealing *** microhardness of the AZ31 and Mg3Y layer decreases firstly and then reaches a stable value,while the microhardness of the interface layer increases gradually with the extension of the annealing *** AZ31/Mg3Y composites exhibit equivalent strength but increased ductility after diffusion annealing,in comparison to the as-rolled AZ31/Mg3Y *** addition,the AZ31/Mg3Y composites after annealing always present higher strength and ductility than AZ31/AZ31 composite,which was fabricated by the same process as that for the AZ31/Mg3Y ***-deformation induced strengthening also plays an important role in the excellent strength and ductility of the annealed AZ31/Mg3Y *** study can provide a direction for improving the plasticity and strength of magnesium alloys synergistically.

关键词： AZ31/Mg3Y composite Accumulated rolling bonding Diffusion annealing Precipitates Strengthening

Robust cooperative multi-agent reinforcement learning via multi-view message certification

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Science China(Information Sciences) 2024年第4期67卷 131-145页

作者： Lei YUAN Tao jiang Lihe LI feng CHEN Zongzhang ZHANG yang YU National Key Laboratory for Novel Software Technology Nanjing University Polixir Technologies

Many multi-agent scenarios require message sharing among agents to promote coordination,hastening the robustness of multi-agent communication when policies are deployed in a message perturbation environment. Major relevant studies tackle this issue under specific assumptions, like a limited number of message channels would sustain perturbations, limiting the efficiency in complex scenarios. In this paper,we take a further step in addressing this issue by learning a robust cooperative multi-agent reinforcement learning via multi-view message certification, dubbed CroMAC. Agents trained under CroMAC can obtain guaranteed lower bounds on state-action values to identify and choose the optimal action under a worst-case deviation when the received messages are perturbed. Concretely, we first model multi-agent communication as a multi-view problem, where every message stands for a view of the state. Then we extract a certificated joint message representation by a multi-view variational autoencoder(MVAE) that uses a product-of-experts inference network. For the optimization phase, we do perturbations in the latent space of the state for a certificate guarantee. Then the learned joint message representation is used to approximate the certificated state representation during training. Extensive experiments in several cooperative multi-agent benchmarks validate the effectiveness of the proposed CroMAC.

关键词： multi-agent reinforcement learning robust communication adversarial training multi-view learning message certification

Microstructure evolution,mechanical properties and fracture behavior of Al-xSi/AZ91D bimetallic composites prepared by a compound casting

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Journal of Magnesium and Alloys 2024年第5期12卷 1944-1964页

作者： Guangyu Li Wenming jiang feng Guan Junwen Zhu yang Yu Zitian Fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this paper,the effect of the Si content on microstructure evolution,mechanical properties,and fracture behavior of the Al-xSi/AZ91D bimetallic composites prepared by compound casting was investigated *** obtained results showed that all the Al-xSi/AZ91D bimetallic composites had a metallurgical reaction layer(MRL),whose thickness increased with increasing Si content for the hypoeutectic Al-Si/AZ91D composites,while the hypereutectic Al-Si/AZ91D composites were *** MRL included eutectic layer(E layer),intermetallic compound layer(IMC layer)and transition region layer(T layer).In the IMC layer,the hypereutectic Al-Si/AZ91D composites contained some Si solid solution and flocculent Mg_(2)Si+Al-Mg IMCs phases not presented in the hypoeutectic Al-Si/AZ91D ***,increasing Si content,the thickness proportion of the T layer increased,forming an inconsistent preferred orientation of the *** shear strengths of the Al-xSi/AZ91D bimetallic composites enhanced with increasing Si content,and the Al-15Si/AZ91D composite obtained a maximum shear strength of 58.6 MPa,which was 73.4% higher than the Al-6Si/AZ91D *** fractures of the Al-xSi/AZ91D bimetallic composites transformed from the T layer into the E layer with the increase of the Si *** improvement of the shear strength of the Al-xSi/AZ91D bimetallic composites was attributed to the synergistic action of the Mg_(2)Si particle reinforcement,the reduction of oxidizing inclusions and the ratio of Al-Mg IMCs as well as the orientation change of the MRL.

关键词： Al/Mg bimetallic composites Si content Mg_(2)Si reinforcement Microstructure Mechanical properties Fracture behavior