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LiNi_(0.7)Co_(0.15)Mn_(0.15)O_2 microspheres as high-performance cathode materials for lithium-ion batteries

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Rare Metals 2014年第5期33卷 608-614页

作者： zhou-Guang Lu Xin-Xin Tan You-Gen Tang ke-chao zhou key Laboratory of Powder Metallurgy Central South University College of Chemical & Chemical Engineering Central South University

Advanced uniform LiNi0.7Co0.15Mn0.15O2 microspheres were successfully synthesized and examined as cathode materials for lithium-ion batteries. The structure,morphology, and electrochemical performance of LiNi0.7-Co0.15Mn0.15O2 calcined at different temperatures ranging from 650 to 900 °C were systematically investigated. The XRD results show that the material has a well-ordered layered structure with small amount of cation mixing. A distinct spherical morphology of the obtained powders prepared at different temperatures can be seen from the SEM images. The as-synthesized LiNi0.7Co0.15Mn0.15O2 powders have a very high-tap density of about 2.37 g·cm^-3. Among all the samples,the sample calcined at 750 °C exhibits the best electrochemical performance with an initial discharge capacity of185.2 mAh·g^-1（3.0–4.3 V, 0.2C rate） and capacity retention〉94.77 %***,thismaterialshowshighspecific capacity and good cycling stability. The LiNi0.7-Co0.15Mn0.15O2 microspheres with high-specific capacity and high-tap density are promising to use as cathode materials for next-generation high-energy-density lithium-ion batteries.

关键词： Lithium-ion batteries High-energy density Microspheres LiNi0.7Co0.15Mn0.15O2 Co-precipitation method

Micro-scratch behavior of WC particle-reinforced copper matrix composites

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Rare Metals 2022年第7期41卷 2337-2342页

作者： ke-chao zhou Hai-Long Pei Jin-Kun Xiao Lei Zhang State key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China

The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 *** influences of normal load and WC content on friction coefficient and wear volume of the composites were *** hardness and scratch resistance of the composites are greatly improved by the addition of *** penetrate depth and residual depth increase near-linearly with normal load increasing and decrease with WC content increasing,and the friction coefficient of the composites also shows the same variation *** valid material removal mechanism is found to transform from micro-plowing to micro-cutting as the normal load increases.

关键词： Metal matrix composite Micro-scratch Wear resistance Friction

Tribological behaviors of Ag-graphite composites reinforced with spherical graphite

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Transactions of Nonferrous Metals Society of China 2020年第8期30卷 2177-2187页

作者： Yang SUN Yan WANG Yun LI ke-chao zhou Lei ZHANG State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Institute of Mechanical and Electrical Engineering Zhengzhou University of Light IndustryZhengzhou 450002China

Two kinds of Ag-graphite composites reinforced with spherical graphite(SG)and conventional flake graphite(FG)were prepared by powder metallurgy *** effect of graphite morphology on the tribological behavior for the Ag-SG and Ag-FG under the dry sliding wear was investigated with a pin-on-disk tribometer at a load of 3.0 N in atmosphere *** results indicated that the minimum wear rate of 3.5×10^-5 mm^3/(N·m)for Ag-FG was achieved and it reduced by nearly an order of magnitude,reaching 1.6×10^-6 mm^3/(N·m)for the *** obviously different tribological behaviors between the Ag-SG and Ag-FG were closely related to the formation of cracks in the *** stress concentration tended to generate at the edges of flake graphite during sliding process,which resulted in the cracks and severe delamination wear of ***,no cracks were found around the spherical graphite in *** spherical graphite can effectively inhibit the initiation and propagation of cracks,achieving high wear resistance.

关键词： Ag-graphite composite graphite morphology wear resistance microstructure wear mechanism

Microstructure and properties of ultrafine WC-Co-VC cemented carbides with different Co contents

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Rare Metals 2022年第6期41卷 1955-1960页

作者： Kai-HuaShi ke-chao zhou Zhi-You Li Xiu-Qi Zan Kai-Lin Dong Qing Jiang State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Precision Parts Department Zigong Cemented Carbide Corporation LimitedZigong 643011China

Ultrafine WC-Co-VC cemented carbides are used extensively in a variety of industrial environments due to their excellent mechanical properties and outstanding wear *** content affects the service performance of the cemented *** the present study,the influ-ences of Co content on microstructure,physical,and mechanical properties were investigated *** WC-Co-VC cemented carbides with Co content varying from 4 wt%and 7 wt%and assistance of VC(0.35 wt%)as inhibitor of WC grain growth were *** physical and mechanical properties were tested and the microstructure characteristics were observed by optical microscope(OM)and scanning electron microscopy(SEM).From the results,it is found that with Co content increasing,both the cobalt magnetism and bending strength increase,while the coercive force,Rockwell hardness,density,and abrasive wear resistance *** addition,the OM and SEM results show that the increase of Co content in WC-Co-VC cemented carbides tends to reduce the quantity and size of micro-pores,and make the fracture mode change from brittle fracture to ductile fracture.

关键词： Ultrafine Cemented carbide Co content Microstructure Properties

New high-strength Ti–Al–V–Mo alloy: from high-throughput composition design to mechanical properties

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1151-1165页

作者： Di Wu Wan-lin Wang Li-gang Zhang Zhen-yu Wang ke-chao zhou Li-bin Liu School of Metallurgy and Environment Central South UniversityChangsha 410083China School of Material Science and Engineering Central South UniversityChangsha 410083China key Laboratory of Non-Ferrous Metallic Materials Science and Engineering Ministry of EducationChangsha 410083China State key Laboratory of Powder Metallurgy Changsha 410083China

The high-throughput diffusion-multiple technique and thermodynamics databases were used to design new high-strength Ti alloys. The composition–microstructure–property relationships of the Ti64–xMo alloys were obtained. The phase fraction and composition of the α and β phases of the Ti64–xMo alloys were calculated using the Thermo-Calc software. After aging at 600℃, the Ti64–6 Mo alloy precipitated ultrafine α phases. This phenomenon was explained on the basis of the pseudo-spinodal mechanism by calculating the Gibbs energy curves of the α and β phases of the Ti64–xMo alloys at 600℃. Bulk forged Ti64–6 Mo alloy exhibited high strength and moderate plasticity after α/β-phase-field solution treatment plus aging. The tensile properties of the alloy were determined by the size and morphology of the primary and secondary α phases and by the β grain size.

关键词： high-strength titanium alloy Ti–6Al–4V–xMo diffusion multiple Thermo-Calc microstructure and mechanical properties

First-principles study of the(Cu_xNi_(1-x))_3 Sn precipitations with different structures in Cu–Ni–Sn alloys

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Chinese Physics B 2018年第8期27卷 423-433页

作者： Guang-Wei Peng Xue-Ping Gan zhou Li ke-chao zhou Stalte key Laborattory of Powder Metallurgy Centra South University Changsha 410083Chin Humm Automottve Engineering Vocaitiomll College Zhtlzhou 4 12001Chitin School of Matcrials Science and Engineering Cwntrat South UniversityChangsha 410083 China

The structural parameters, the formation energies, and the elastic and thermodynamic properties of the （CuxNi1-x）3Sn phase with different structures are studied by the virtual crystal approximation （VCA） and super-cell （SC） methods. The lattice constants, formation energies, and elastic constants obtained by SC and VCA are generally consistent with each other. It can be inferred that ttle VCA method is suitable for （CuxNil ,）3Sn ordered phase calculation. The calculated results show that the equilibrium structures of Cu3Sn and Ni3Sn are D0a and D019 respectively. （CuxNi1-x）3Sn D03 with various components are the mctastable phase at temperature of 0 K, just as D022 and L I2. With the temperature increase, tile free energy of the D03 is lower than those of D022 and L12, and D022 and L12 eventually turn into D03 in tile aging process. The （CuxNi1-x）3Sn D022 is first precipitated in a solid solution because its structure and cell volume are most similar to Ihose of a solid solution matrix. The LI2 and the D022 possess better mechanical stability than the D03. Also, they may play a more important role in the strengthening of Cu-Ni-Sn alloys. This study is valuable lk）r further research on Cu-Ni-Sn alloys.

关键词： (CuxNi1-x)3Sn, first-principle virtual crystal approximation super-cell

Nanospike surface-modified bionic porous titanium implant and in vitro osteogenic performance

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Transactions of Nonferrous Metals Society of China 2017年第8期27卷 1815-1821页

作者： Guo-hui WANG Hua FU ke-chao zhou Yan-zhong ZHAO Shai-hong ZHU Third Xiangya Hospital of Central South University Central South University Changsha 410013 China State key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

This work aimed to prepare the nanospike surface-modified bionic porous titanium implants that feature favorableosteointegration performance and anti-bacterial *** implant was prepared using freeze casting,and nanospikesurface-modification of the implant was performed using thermal *** pore morphology and size,mechanical properties,and osteogenic performance of the implants were analyzed and *** results showed that when the volume ratio of titaniumpowder in slurry was set to be10%,the porosity,pore diameter,compressive strength,and elastic modulus of the porous sampleswere(58.32±1.08)%,(126.17±18.64)μm,(58.51±20.38)MPa and(1.70±0.52)GPa,*** the porous sample wassintered at a temperature of1200°C for1h,these values were(58.24±1.50)%,(124.16±13.64)μm,(54.77±27.55)MPa and(1.63±0.30)GPa,*** nanospike surface-modified bionic porous titanium implants had favorable pore morphology andsize,mechanical properties and osteointegration performance through technology optimization,and showed significant clinicalapplication prospect.

关键词： nanospike surface-modification bionic porous titanium osteogenic performance freeze casting thermal oxidation

Bone integration properties of antibacterial biomimetic porous titanium implants

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Transactions of Nonferrous Metals Society of China 2017年第9期27卷 2007-2014页

作者： Guo-hui WANG Hua FU Yan-zhong ZHAO ke-chao zhou Shai-hong ZHU The Third Xiangya Hospital of Central South University Changsha 410013 China State key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

A novel antibacterial biomimetic porous titanium implant with good osseointegration was prepared by freeze-casting and thermal *** integration properties of the porous titanium implant were evaluated by cell proliferation assay,alkaline phosphatase activity assay,X-ray examination and hard bone tissue *** in vitro cell proliferation and the level of differentiation of the group with a modified nano-porous implant surface were significantly higher than those in the group without surface modification and the dense titanium control group(P<0.05).In vivo,bone growth and osteogenesis were found in the experimental groups with modified and unmodified porous titanium implants;osteoblasts in the modified group had more mature differentiation in the pores compared to the unmodified *** implants can form solid,biologically compatible bone grafts with bone tissues,exhibiting good osseointegration.

关键词： antibacterial function surface modification porous titanium implant osseointegration freeze-casting

Comparison of flow behaviors of near beta Ti-55511 alloy during hot compression based on SCA and BPANN models

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Transactions of Nonferrous Metals Society of China 2021年第6期31卷 1665-1679页

作者： Shuang-xi SHI Xiu-sheng LIU Xiao-yong ZHANG ke-chao zhou State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Wuhan Research Institute of Materials Protection Wuhan 430030China Shenzhen Research Institute Central South UniversityShenzhen 518057China

The flow behavior of Ti-55511 alloy was studied by hot compression tests at temperatures of 973−1123 K and strain rates of 0.01−10 s^(−1).Strain-compensated Arrhenius(SCA)and back-propagation artificial neural network(BPANN)methods were selected to model the constitutive relationship,and the models were further evaluated by statistical analysis and *** stress−strain data extended by two models were implanted into finite element to simulate hot compression *** results indicate that the flow stress is sensitive to deformation temperature and strain rate,and increases with increasing strain rate and decreasing *** the SCA model fitted by quintic polynomial and the BPANN model with 12 neurons can describe the flow behaviors,but the fitting accuracy of BPANN is higher than that of *** cross-validation tests also confirm that the BPANN model has high prediction *** models are effective and feasible in simulation,but BPANN model is superior in accuracy.

关键词： Ti-55511 alloy flow stress Arrhenius constitutive equation back-propagation artificial neural network finite element