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Effect of Sintering Temperature and Hydrophobic Treatment on the Microstructure and Properties of Copper-Graphite Composites

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Journal of Wuhan University of Technology(Materials Science) 2022年第3期37卷 305-313页

作者： zou jianpeng WEI Hongming XIAO Cong State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China State Key Laboratory for System Integration of High Power AC Drive Electric Locomotive Zhuzhou 412001China

Copper-graphite composites were prepared by spark plasma sintering(SPS)using coppercoated graphite *** surfaces were successfully constructed by chemical etching and surface *** density,metallographic structure,microstructure,Shore hardness,resistivity,water contact angle,and friction/wear properties of the composites were investigated using the Archimedes drainage method,a metallographic microscope,a scanning electron microscope,a hardness tester,a resistometer,a surface science tester,and a friction *** results showed that the relative density and Shore hardness of the copper-graphite composites increased slightly from 90.04%and 56 HSD to 92.66%and 59 HSD,respectively,when the sintering temperature increased from 700 to 900℃.The copper and graphite phases in the copper-graphite composites were uniformly distributed with a continuous and network-like structure at various sintering *** interface between the copper and graphite was in good condition,without any obvious cracks or *** optimum process for hydrophobic surface construction included etching with a 1 mol/L K_(2)Cr_(2)O_(7)-H_(2)SO_(4)solution for 1 min,and soaking in a 0.09 mol/L cetylbenzene sulfonic acid alcohol solution for 1 *** contact angle of the copper-graphite composite reached 130°.Hydrophobic treatment was beneficial for reducing the friction coefficient(from 0.18-0.19 to 0.13-0.15)and the wear rate(from 4.1-6.2×10^(-3)to 1.1-2.1×10^(-3)mm^(3)/(N·m)),demonstrating obvious antifriction and wear-resisting *** resistivities of the hydrophobic-treated samples increased slightly,from(4-8)×10^(-7)Ω·m to(5-15)×10^(-7)Ω·m,meeting the resistivity requirements of copper-graphite composite pantograph sliders and current receiver sliders in actual working conditions.

关键词： spark plasma sintering(SPS) copper-graphite composite chemical etching shore hardness friction and wear properties resistivity

Exceptional strength-ductility synergy of additively manufactured CoCrNi medium-entropy alloy achieved by lattice defects in heterogeneous microstructures

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Journal of Materials Science & Technology 2022年第32期127卷 61-70页

作者： Jianying Wang jianpeng zou Hailin Yang Lijun Zhang Zhilin Liu Xixi Dong Shouxun Ji State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Light Alloy Research Institute College of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China Brunel Centre for Advanced Solidification Technology(BCAST) Brunel University LondonUxbridgeMiddlesex UB83PHUnited Kingdom

The selective laser melting(SLM)with subsequent cold rolling and annealing is used to produce high-density lattice defects and grain refinement in the CoCrNi medium-entropy alloys(MEAs).The superior comprehensive mechanical properties have been achieved in the as-SLMed CoCrNi alloy after rolling and *** as-SLMed alloys delivered the yield strength of 693.4 MPa,the ultimate tensile strength of 912.7 MPa and the fracture strain of 54.4%.After rolling with 70%reduction in thickness and annealing at 700℃for 2 *** yield strength,ultimate tensile strength and fracture strain reached 1161.6 MPa,1390.8 MPa and 31.5%,*** exceptional strength-ductility synergy is mainly attributed to the refined hierarchical microstructures with coarsening grains at a level of 30μm and ultrafine grains at a level of 1μm,and the heritage of dislocation-formed sub-grains and other lattice *** investigation demonstrates that the SLM with subsequent rolling and annealing is beneficial to fabricate high strength and ductile MEAs with single face-centered cubic(fcc)structure.

关键词： Medium-entropy alloys Selective laser melting Strength-ductility synergy Defects Microstructure

Rheological responses of fumed silica suspensions under steady and oscillatory shear

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Science China(Technological Sciences) 2009年第4期52卷 910-915页

作者： YANG HaiLin RUAN JianMing zou jianpeng WU QiuMei ZHOU ZhongCheng ZHOU ZhiHua State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Rheological experiments under steady and oscillatory shear were conducted for fumed silica suspen- sions in polyethylene glycol. Under steady shear the shear-thinning and thickening response were exhibited and the flow exponent N was determined. With the increase of concentration the flow exponent N showed a rapid increase, and it increased dramatically when the discontinuous shear-thickening took place. Oscillatory shear experiments were conducted at constant frequency and constant amplitude strain, respectively. The shear-thinning and the discontinuous shear-thickening behavior were observed under different constant frequencies from 10 to 80 rad/s. The correlation between complex modulus (G*) and sweep frequency (ω) was illuminated at γ =750%. It was found that the correlation between G* and ω could be fitted by equation: G*∝ωn. The indexes in shear-thinning region and shear-thickening were determined. The indexes were similar to some extent at shear-thinning region and increased dramati- cally to a much higher value when the shear-thickening occurred,especially at higher weight fractions. The behaviors can be qualitatively explained as follows: the shear-thinning owes to decrease of viscos- ity, which results from disruption of the aggregates; the cluster theory attributes the shear-thickening to the formation of metastable, flow induced clusters, which block the system.

关键词： fumed silica suspension shear-thickening steady shear dynamic oscillatory shear rheological response

Ultrastrong and ductile(CoCrNi)_(94)Ti_(3)Al_(3)medium-entropy alloys via introducing multi-scale heterogeneous structures

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Journal of Materials Science & Technology 2023年第4期135卷 241-249页

作者： Jianying Wang jianpeng zou Hailin Yang Xixi Dong Peng Cao Xiaozhou Liao Zhilin Liu Shouxun Ji State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Brunel Centre for Advanced Solidification Technology(BCAST) Brunel University LondonUxbridgeMiddlesex UB83PHUnited Kingdom Department of Chemical and Materials Engineering The University of Auckland1142New Zealand School of Aerospace Mechanical&Mechatronic EngineeringThe University of SydneySydneyNSW 2006Australia Light Alloy Research Institute College of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China

The coarsening-grained single-phase face-centered cubic(fcc)medium-entropy alloys(MEAs)normally exhibit insufficient strength for some engineering ***,superior mechanical properties with ultimate tensile strength of 1.6 GPa and fracture strain of 13.1%at ambient temperature have been achieved in a(CoCrNi)_(94)Ti_(3)Al_(3)MEA by carefully architecting the multi-scale heterogeneous *** microscopy characterization indicates that the superior mechanical properties mainly originated from the favorable heterogeneous fcc matrix(1-40μm)and the coherent sphericalγ’precipitates(10-100 nm),together with a high number density of crystalline defects(2-10 nm),including dislocations,small stacking faults,Lomer-Cottrell locks,and ultrafine deformation twins.

关键词： Medium-entropy alloys Mechanical properties Heterogeneous structure γ’nanoprecipitates Crystalline defects

Recent Advances in Interface Modification of Cu/graphite Composites and Layered Ternary Carbides of Modified Layer Candidate

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1061-1072页

作者： WEI Hongming LI Mingchao LI Xiaoya ZHAN Wenyi LI Feiyang DAI Yanzhang zou jianpeng State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Guangxi Fangchenggang Nuclear Power Co. Ltd.Fangchenggang 538000China

We review the fundamental properties and significant issues related to Cu/graphite *** particular,recent research on the interfacial modification of Cu/graphite composites is addressed,including the metal-modified layer,carbide-modified layer,and combined modified ***,we propose the use of ternary layered carbide as an interface modification layer for Cu/graphite composites.

关键词： Cu/graphite composites interfacial bonding surface modification wettability layered ternary carbides

Failure mechanism and interfacial diffusion behavior of Ru-doped NiAlHf coatings at 1200℃

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Advanced Powder Materials

Advanced Powder Materials 2023年第1期2卷 1-14页

作者： Hongzhi Yang Xiaoya Li jianpeng zou Qian Shi Mingjiang Dai Changguang Deng Pengbo Lyu State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China Institute of New Materials National Engineering Laboratory for Modern Materials Surface Engineering TechnologyKey Lab of Guangdong for Modern Surface Engineering TechnologyGuangdong Academy of SciencesGuangzhou510651China Key Laboratory of Materials Design and Preparation Technology of Hunan Province School of Materials Science and EngineeringXiangtan UniversityXiangtan411105China Institut Charles Gerhardt Montpellier UMR 5253CNRSUniversite de MontpellierMontpellierFrance

Ru-doped NiAlHf coatings were deposited on Ni-based single crystal substrate by arc ion plating *** failure mechanism and interfacial diffusion behavior were comparatively investigated with NiAlHf coating using scanning electron microscopy,electron probe micro-analyzer,and transmission electron *** results indicated that microstructure evolution of oxide scale induced by element diffusion process significantly affected oxidation resistance of NiAlHf/Ru coatings,resulting in formation of cracks and voids,thereby accelerating failure *** precipitates in interdiffusion zone and secondary reaction zone of the substrate initiated by interfacial element diffusion were P phase andσphase,*** the discrepancy in content was elucidated from the perspective of thermodynamics and ***,microstructural evolution between NiAlHf/Ru coatings and substrate was also *** research could not only provide profound understanding of NiAlHf/Ru coatings failure mechanism,but also had significant guidance for suppressing precipitation of topological close-packed phases and facilitating development of single crystal Ni-based superalloys.

关键词： NiAlHf/Ru coatings failure mechanism Diffusion behavior TCP phases Interfacial microstructure evolution

包埋法制备NiAl涂层NiCrW基高温合金的抗氧化性能

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稀有金属材料与工程 2022年第3期51卷 814-820页

作者：高杉邹俭鹏中南大学粉末冶金国家重点实验室湖南长沙410083 大功率交流传动电力机车系统集成国家重点实验室湖南株洲412001

以CaCl_(2)为活化剂,采用包埋法在NiCrW基高温合金表面制备了NiAl涂层。采用X射线衍射、扫描电子显微镜和能谱仪对涂层表面和横截面进行了分析。结果表明,CaCl_(2)可以替代NH_(4)Cl,是一种有效的活化剂。在950℃下,通过4 h的包埋渗铝,... 详细信息

以CaCl_(2)为活化剂,采用包埋法在NiCrW基高温合金表面制备了NiAl涂层。采用X射线衍射、扫描电子显微镜和能谱仪对涂层表面和横截面进行了分析。结果表明,CaCl_(2)可以替代NH_(4)Cl,是一种有效的活化剂。在950℃下,通过4 h的包埋渗铝,制备出几乎为单相、厚度为30μm的NiAl涂层,涂层与基体之间为富铬中间层。当包埋渗剂填充率小于100%时,NiAl层表面生成针状θ-Al_(2)O_(3)。在1000℃恒温空气氧化试验中,NiAl涂层开始时被高速氧化,然后逐渐变为缓慢氧化,完成了亚稳态针状θ-Al_(2)O_(3)向稳态不规则颗粒状αAl_(2)O_(3)的转变,最终稳定的α-Al_(2)O_(3)为基体提供了良好的抗氧化保护。

关键词： NiCrW基高温合金 NiAl涂层包埋法抗氧化

Fabrication and Growing Kinetics of Highly Dispersed Gadolinium Zirconate Nanoparticles

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Research and Application of Materials Science 2019年第1期1卷 28-34页

作者： Renbo Zhu jianpeng zou Jie Mao Xiaofeng Zhang Chunming Deng Min Liu Wenlong Chen School of Materials Science and Engineering University of New South WalesSydneyAustralia State Key Laboratory of Powder Metallurgy Central South UniversityChangshaChina National Engineering Laboratory for Modern Materials Surface Engineering Technology&the Key Lab of Guangdong for Modern Surface Engineering Technology Guangdong Institute of New MaterialsGuangzhouChina Guangdong Industrial Analysis and Testing Center GuangzhouChina

Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain growth kinetics were *** results suggest that the nanoparticles were obtained through hydroxide dehydration and solid phase *** dispersion was accomplished by ethanol solvent to reduce the hydrogen bond and sodium dodecyl benzene sulfonate(SDBS)surfactant to increase the electrostatic repulsion between the *** grain growth activation energy of GZ powders calcined at lower temperature(1200°C)is 148.4 kJ/mol(Qh).The current study shows that the optimal process to synthesize dispersed GZ nanoparticles includes ethanol solvent,3 wt.%SDBS surfactant,and 1100°C as calcining temperature.

关键词： Gadolinium zirconate Co-precipitation method Phase structure Kinetics Dispersed nanoparticles

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泡沫浸渍法制备的多孔铌基生物材料及性能

稀有金属材料与工程 2010年第11期39卷 2015-2017页

作者：节云峰邹俭鹏阮建明 Cent S Univ Powder Met Res Inst State Key Lab Powder Met Changsha 410083 Peoples R China

采用新型的泡沫浸渍法,以聚氨酯泡沫为载体制备出具有较高强度和良好生物相容性的多孔铌基材料。并借助分析天平、XRD、CS600碳硫测试仪和SEM对多孔铌的孔隙度、性能和微观结构进行了测试及观察。结果表明:制成的多孔铌,具有三维、连通... 详细信息

采用新型的泡沫浸渍法,以聚氨酯泡沫为载体制备出具有较高强度和良好生物相容性的多孔铌基材料。并借助分析天平、XRD、CS600碳硫测试仪和SEM对多孔铌的孔隙度、性能和微观结构进行了测试及观察。结果表明:制成的多孔铌,具有三维、连通孔隙结构且无任何杂质相,孔隙率为71.4%,孔径尺寸为500μm,平均密度为2.45g/cm3。三维连通多孔铌的平均弹性模量为815MPa,抗压强度为36.62MPa,与人体松质骨的力学性能相匹配。

关键词：聚氨酯泡沫浸渍法制备多孔生物材料力学性能 via 生物相容性载体制备微观结构三维平均密度连通孔隙结构孔径尺寸抗压强度分析天平弹性模量测试仪杂质相松质骨