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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

Selective laser melted near-beta titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe:Microstructure and mechanical properties

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Journal of Central South University 2021年第6期28卷 1601-1614页

作者： HUANG Hua-long LI Dan CHEN chao LI Rui-di ZHANG Xiao-yong LIU Shi-chao ZHOU ke-chao State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Shenzhen Research Institute Central South UniversityShenzhen 518057China

In this work,a near-beta Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy was fabricated by selective laser melting(SLM),and the microstructure evolution together with the mechanical properties was *** as-fabricated alloy showed columnarβgrains spreading over multiple layers and paralleling to the building *** distinct microstructure of as-fabricated alloy was composed of near-β(more than 98.1%)with a submicron cellular *** SLM processing parameters such as hatch spacing could affect the microstructure of as-fabricated alloy,which could thus further significantly affect the mechanical properties of as-fabricated *** addition,the as-fabricated alloy with the distinct microstructure exhibits yield strength of 818 MPa combined with elongation of more than 19%,which shows that SLM is a potential technology for manufacturing near-beta titanium components.

关键词： selective laser melting Ti-5Al-5Mo-5V-1Cr-1Fe near-βandβ-titanium alloy cellular structure precipitation

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

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WC-Ni基硬质合金的光固化增材制造

稀有金属与硬质合金 2024年第2期52卷 76-88页

作者：刘展赫陈子航王日初彭超群时凯华周科朝马格达西·什洛莫王小锋中南大学材料科学与工程学院湖南长沙410083 中钨高新材料股份有限公司湖南株洲412000 中南大学粉末冶金国家重点实验室湖南长沙410083 耶路撒冷希伯来大学化学研究所耶路撒冷91904

采用光固化增材制造(3D打印)技术制备WC-Ni基硬质合金,研究了浆料配比和增材制造工艺参数对浆料流变性能和固化性能的影响以及WC-Ni基硬质合金的性能。结果表明:当浆料固含量为40%(体积分数)、分散剂为ZN-1344且加入量为粉体质量的2%时,... 详细信息

采用光固化增材制造(3D打印)技术制备WC-Ni基硬质合金,研究了浆料配比和增材制造工艺参数对浆料流变性能和固化性能的影响以及WC-Ni基硬质合金的性能。结果表明:当浆料固含量为40%(体积分数)、分散剂为ZN-1344且加入量为粉体质量的2%时,WC-Ni浆料的流变性能满足增材制造工艺需求,当剪切速率为100 s^(-1)时,浆料黏度为2.718 Pa·s;该浆料的最大单层固化厚度可达144μm,对应工艺参数为0.01 mm线间距、90%激光功率和2 000 mm/s扫描速度;采用响应曲面法拟合数据获得的浆料单层固化厚度计算模型,计算值与实际值误差为3.4%,可起理论预测作用;光固化增材制造WC-15%Ni硬质合金的密度和相对密度最高,分别为13.51 g/cm^(3)和96.5%,加入1%晶粒长大抑制剂Cr_(3)C_(2)后,硬质合金维氏硬度显著提高,达到945 HV_(30),接近同等Ni含量但不含有Cr_(3)C_(2)的传统硬质合金硬度。

关键词： WC-Ni基硬质合金光固化增材制造 3D打印响应曲面法晶粒长大抑制剂复杂结构

Tribological behavior of Cu-15Ni-8Sn/graphite under sea water, distilled water and dry-sliding conditions

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Journal of Central South University 2019年第10期26卷 2623-2633页

作者： WANG Yan ZHANG Lei ZHAI Hong-fei GAO Hong-xia ZHOU ke-chao Henan key Laboratory of Intelligent Manufacturing of Mechanical Equipment Institute of Mechanical and Electrical EngineeringZhengzhou University of Light IndustryZhengzhou 450002China State key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China

The tribological behaviors of Cu-15Ni-8Sn/graphite composites with the graphite content of 38 vol.%against AISI321 stainless steel under dry-sliding,deionized water and sea water were investigated on a block-on-ring *** results indicated that the friction coefficient was the lowest under dry-sliding,and the highest in deionized *** wear rate decreased to reach the minimum value of 1.39×10-15 m3/(N·m)in sea water and in deionized water,it increased to the maximum value of 5.56×10-15 m3/(N·m).The deionized water hindered the formation of tribo-oxide layer and lubricating film,which resulted in the largest friction coefficient and wear *** sea water,however,the corrosion products comprised of oxides,hydroxides and chlorides were found on the worn surface,and the compacted layer composed of corrosion products and graphite played an important role in keeping the excellent wear *** was elucidated that the tribological behaviors of Cu-15Ni-8Sn/graphite composite were powerful influenced by the friction environments.

关键词： self-lubricating composites tribological behavior compacted layers corrosion products sea water

Wear map for sliding wear behavior of Cu-15Ni-8Sn alloy against bearing steel under oil-lubricated condition

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Journal of Central South University 2020年第2期27卷 311-324页

作者： CHENG Jin-juan GAN Xue-ping LI Zhou LEI Qian ZHOU ke-chao State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China

Wear behaviors of a peak-aged Cu-15Ni-8Sn alloy fabricated by powder metallurgy were *** results indicated that the friction coefficients and the wear rates of Cu-15Ni-8Sn alloy within a normal load range of 50−700 N and a sliding speed range of 0.05−2.58 m/s were less than 0.14 and 2.8×10−6 mm3/mm,***-like curve and wear map were developed to describe the oil-lubrication mechanism and wear *** equation of the dividing line between zones of safe and unsafe wear life was *** oil was squeezed into micro-cracks under severe wear *** addition,the lubricating oil reacted with Cu-15Ni-8Sn alloy to generate the corresponding sulfides,which hindered the repair of micro-cracks,promoted cracks growth,and led to *** work has established guidelines for the application of the Cu-15Ni-8Sn alloy under oil-lubricated conditions through developing wear map.

关键词： Cu-15Ni-8Sn alloy oil lubrication wear behavior wear map

A Software Pattern of the Genetic Algorithm ——a Study on Reusable Object Model of Genetic Algorithm

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Wuhan University Journal of Natural Sciences 2001年第Z1期6卷 209-217页

作者： Zhuo Shi, Liu chao, He ke\|qing School of Computer,Wuhan University, Wuhan 430072, China School of Computer Wuhan University Wuhan 430072 China

The Genetic Algorithm (GA) has been a pop research field, but there is little concern on GA in view of Software Engineering and this result in a series of problems. In this paper, we extract a GA's software pattern, draw a model diagram of the reusable objects, analyze the advantages and disadvantages of the pattern, and give a sample code at the end. We are then able to improve the reusability and expansibility of GA. The results make it easier to program a new GA code by using some existing successful operators, thereby reducing the difficulties and workload of programming a GA's code, and facilitate the GA application.

关键词： genetic algorithm software pattern UML

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