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Process Optimization for Cerium Oxide Based Conversion Coating of AZ91D Magnesium Alloy at Room Temperature

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稀有金属材料与工程 2012年第S1期41卷 243-246页

作者： chen dongchu Wu Jianfeng Ye Shulin Foshan Univ Sch Sci Foshan 528000 Peoples R China

The Ce2SO4/H2O2 containing solution is used to prepare a chrome-free cerium oxide based chemical conversion coating on AZ91D magnesium alloy at room temperature,and an orthogonal experiment was carried out to optimize the treating *** effect of preparing parameters on the coating growth and the corrosion resistance were *** was found that H2O2 is the dominant influence factor on the coating weight gain in the orthogonal experiment,with Ce(SO4)2 coming next and immersion time having the least impact,while the most dominant influence factor on the corrosion resistance is Ce(SO4)2,with H2O2 coming next and immersion time having the least *** coating has the best corrosion resistance,treated in the solution of 10 g/l Ce(SO4)2 and 12 ml/l H2O2 for 4 *** was adopted to study the micro-morphology of the conversion coating on magnesium alloy surface The prolonged immersion time duration or the increased concentration of Ce(SO4)2 and H2O2 will increase the coating thickness,but tiny cracks appears resulted from the fast coating deposition.

关键词： magnesium alloy cerium conversion coating chrome-free room temperature

Selective laser melting of bulk immiscible alloy with enhanced strength:Heterogeneous microstructure and deformation mechanisms

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Journal of Materials Science & Technology 2022年第9期104卷 81-87页

作者： Shengfeng Zhou Min Xie Changyi Wu Yanliang Yi dongchu chen Lai-Chang Zhang MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou 510632China School of Materials Science and Engineering Tianjin Polytechnic UniversityTianjin 300387China Department of Educational Science Hunan First Normal UniversityChangsha 410205China School of Materials Science and Energy Engineering Foshan UniversityFoshan 528225China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia

To overcome the dimension limits of immiscible alloys produced by traditional techniques and enhance their mechanical properties,bulk Cu-Fe-based immiscible alloy with abundant nanotwins and stacking faults was successfully produced by selective laser melting(SLM).The SLM-produced bulk immiscible alloy displays a heterogeneous microstructure characterized by micro-scaledγ-Fe particles dispersed in fineε-Cu matrix with a high fraction(~92%)of high-angle grain ***,abundant nanotwins and stacking faults are generated in the interior of nano-scaledγ-Fe particles embedded withinε-Cu *** heterogeneous interface of soft domains(ε-Cu)and hard domains(γ-Fe)not only induces the geometrically necessary dislocations(GNDs)but also affects the dislocation propagation during plastic ***,the bimodal heterogeneous interface,and the resistance of nanotwins and stacking faults to the propagation of partial dislocation make the bulk immiscible alloy exhibit an enhanced strength of~590 MPa and a good ductility of~8.9%.

关键词： Immiscible alloy Selective laser melting Heterogeneous microstructure Nanotwins Stacking faults

Functional ceramic support as an independent catalyst layer for direct liquid fuel solid oxide fuel cells

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Journal of Advanced Ceramics 2023年第3期12卷 474-486页

作者： Jie Luo Kai Zhao Jishi Zhao Jun Li Yihui Liu dongchu chen Qing Xu Min chen School of Materials Science and Hydrogen Energy Foshan UniversityFoshan 528000China Guangdong Key Laboratory for Hydrogen Energy Technologies Foshan UniversityFoshan 528000China Foshan Institute of Environment and Energy Technology Foshan 528000China R&D Center of Hydrogen Energy Standardization Yunfu 527300China Hubei Key Laboratory of Advanced Technology for Automotive Components&Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

A porous ceramic support is designed as a multi-functional independent catalyst layer for solid oxide fuel cells(SOFCs)running on liquid hydrocarbon *** layer consists of a highly porous Ce_(0.9)Ca_(0.1)O_(2−δ)ceramic backbone and active NiMo catalysts,which could be integrated into the conventional Ni metal containing the anode for internal reforming of the hydrocarbon *** to conventional catalyst layers sintered on the anodes,this independent catalyst layer could be simply assembled on top of the anode without additional sintering,thereby avoiding the mismatch of the thermal expansion coefficient between the catalyst layer and the anode and improving stability of a single ***,a current collector layer could be inserted between the catalyst and the anode to enhance current collection efficiency and electrochemical performance of the single *** 750℃,the independent catalyst layer displays high activity towards the catalytic decomposition of methanol,and the single cell could achieve the maximum power density of 400–500 mW·cm^(−2)in dry ***,by employing the independent catalyst layer,the single cell offers additional in-situ catalyst regeneration capability under the methanol operation *** 10 mL·min−1 air into an anode channel for 5 min is found to be effective to burn out carbon species in the catalyst layer,which reduces the degradation rate of the cell voltage by orders of magnitude from 2.6 to 0.024 mV·h−1 during the operation of 360 h in dry *** results demonstrate the significance of the independent catalyst layer design for direct internal reforming methanol fuel cells.

关键词： independent catalyst layer NiMo-Ce_(0.9)Ca_(0.1)O_(2−δ)catalyst internal reforming methanol solid oxide fuel cell(SOFC)

Ultralow-temperature assisted synthesis of single platinum atoms anchored on carbon nanotubes for efficiently electrocatalytic acidic hydrogen evolution

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Journal of Energy Chemistry 2020年第12期29卷 280-292页

作者： Wenwu Zhong Wenguang Tu Zongpeng Wang Zhiping Lin Aijiao Xu Xiufang Ye dongchu chen Beibei Xiao Department of Materials Taizhou UniversityTaizhou 318000ZhejiangChina School of Energy and Power Engineering Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina School of Material Science and Energy Engineering Foshan UniversityFoshan 528001GuangdongChina School of Mechanical df Aerospace Engineering Nanyang Technological UniversitySingapore637459Singapore

Although platinum(Pt) is highly active for hydrogen evolution reaction(HER)[1], it is crucial to explore the effective approach for minimizing the Pt loading amount in the practical application. Herein, one ultralow-temperature solution reduction approach is developed to anchor atomically dispersed Pt atoms on carbon nanotubes(Pt-CNTs), which decelerates the diffusion rate of Pt Cl2-6 ion reached onto the carbon nanotubes and lowers the free energy of Pt atoms in the solution to reduce the probability of the Pt aggregation. The obtained Pt-CNTs exhibits a low overpotential of 41 mV@10 mA cm^(-2) for HER in acidic media. The calculation results revealed that the improvement of the electrocatalytic activity is contributed by the interaction between CNTs and Pt atoms, which descreases the the Pt d band cneter referred to the Fermi level and lowers the Gibbs free energy of H*adsorption. This work may provide one easy and convenient strategy for the large-scale use of Pt catalysts in practical applications.

关键词： Hydrogen evolution reaction Single-atom catalysts Ultralow-temperature Platinum Carbon nanotubes

Highly dispersed CeO_(2-x)nanoparticles with rich oxygen vacancies enhance photocatalytic performance of g-C_(3)N_(4)toward methyl orange degradation under visible light irradiation

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Journal of Rare Earths 2022年第8期40卷 1255-1263页

作者： Xuejun Xu Tianhua Huang Yisheng Xu Huawen Hu Shuang Liao Xiaohong Hu dongchu chen Min Zhang School of Materials Science and Hydrogen Energy Foshan UniversityFoshan 528000China Guangdong Key Laboratory for Hydrogen Energy Technologies Foshan 528000China

CeO_(2)/g-C_(3)N_(4)photocatalysts have attracted tremendous attention in the photocatalytic degradation of organic *** design and construction of highly active CeO_(2)/g-C_(3)N_(4)photocatalysts without harsh conditions are still ***,highly dispersed CeO_(2-x)nanoparticles with rich oxygen vacancies were successfully precipitated on the surface of g-C_(3)N_(4)under mild *** fabricated CeO_(2-x)/g-C_(3)N_(4)exhibits remarkable activity and stability for photocatalytic degradation of MO *** optimal rate constant of MO degradation over CeO_(2-x)/g-C_(3)N_(4)is about 0.031 min^(-1),which is three times higher than that of g-C_(3)N_(4).A negligible activity decrease is observed after three cycling *** enhanced catalytic performance can be ascribed to the excellent dispersion of CeO_(2-x)with rich oxygen vacancies that benefit O_(2)adsorption and visible light *** addition,the proper band alignment between CeO_(2-x)and gC_(3)N_(4)is conducive to the highly efficient separation of photogenerated electron-hole pairs.

关键词： CeO_(2-x) G-C_(3)N_(4) Heterojunctions Oxygen vacancies Rare earths

Facile Li-Al layered double hydroxide films on Al alloy for enhanced hydrophobicity, anti-biofouling and anti-corrosion performance

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Journal of Materials Science & Technology 2021年第20期79卷 230-242页

作者： Ji Li Tianci Yuan chengliang Zhou Bo chen Yi Shuai Dawang Wu dongchu chen Xiaohu Luo Y.Frank cheng Yali Liu State Key Laboratory for Chemo/Biosensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha410082China Department of Mechanical and Manufacturing Engineering University of CalgaryCalgaryAlbertaT2N 1N4Canada School of Chemistry and Chemical Engineering Qiannan Normal University for NationalitiesDuyun558000China College of Mechanical Engineering and Applied Electronics Technology Beijing University of TechnologyBeijing100124China School of Material Science and Energy Engineering Foshan UniversityFoshan528000China

In this work,lithium(Li)-aluminum(Al)layered double hydroxide(LDH)films modified by 4-amino-2-((hydrazine methylene)amino)-4-oxobutanoic acid(denoted as AOA acid)and/or 1H,1H,2H,2H-perfluorooctyltriethoxysilane were prepared on 6N01 Al alloy by a facile,in-situ growth method with enhanced hydrophobicity,anti-biofouling and anti-corrosion *** preparation is low energy consumptive and environment friendly,relying on self-assembly at ambient *** structure,molecular weight and functional groups of the synthesized AOA acid were characterized by NMR spectrometer,ESI-MS spectrometer and Fourier transform infrared(FT-IR)*** the compositions,structure and morphology of the films were characterized by Fourier transform infrared(FT-IR)spectroscopy,glancing-angle X-ray diffraction(GA-XRD),X-ray photoelectron spectroscopy(XPS),field emission scanning electron microscopy(FE-SEM)and energy-dispersive x-ray spectrum(EDS).Water contact angle measurements(CA)and atomic force microscopy(AFM)characterization show that the films possess a micro/nanostructure with an improved *** test,neutral salt tests(NSS)and electrochemical impedance spectroscopy(EIS)conducted in 3.5 wt.%NaCl solutions demonstrate the improved corrosion resistance of the films over bare Al ***,the films also possess an excellent anti-bacterial property toEscherichia coli,Bacillus subtilis and sulfate-reducing bacteria.

关键词： Li-Al layered double hydroxides Anti-biofouling Hydrophobicity Anti-bacterial Anti-corrosion

Nucleation and growth of L1_(2)-Al_(3)RE particles in aluminum alloys:A first-principles study

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Journal of Rare Earths 2023年第7期41卷 1116-1126,I0005页

作者： Touwen Fan Zixiong Ruan Feng Zhong Chaoyang Xie Xiaofeng Li dongchu chen Pingying Tang Yuanzhi Wu College of Science Hunan Institute of TechnologyHengyang 421002China Research Institute of Automobile Parts Technology Hunan Institute of TechnologyHengyang 421002China School of Materials Science and Engineering North University of Chin1Taiyuan 030051China School of Material Science and Hydrogen Energy Engineering Foshan UniversityFoshan 528001China Key Laboratory of New Electric Functional Materials of Guangxi Colleges and Universities Nanning Normal UniversityNanning 530023China

The internal mechanisms of nucleation and growth of L1_(2)-AI_(3)RE(RE=Sc,Y,La-Lu) second phases in Al alloys were investigated by combining first-principles calculations with quasi-harmonic approximation(QHA).The calculated results show that the diffusion rate D_s and chemical potential AG_V increase with the increase of *** the increase of atomic number,the D_s and the strain energy ΔE_(CS)increase firstly from Sc to La,and then decreases,while the calculated interface energy γ_(α/β) and ΔG_V show opposite *** on above calculated results,the critical nucleation radius R*and coarsening rate K_(LSW) are obtained from the classical nucleation theory(CNT) and LSW model of the Ostwald ripening of particles,*** the increase of atomic number,the R*increases firstly,and then decreases for all planes at finite *** the K_(LSW) shows opposite variation to the R^(*).From this point of view,it is reasonably speculated that Y and later RE elements can replace the expensive Sc for heat-resistance Al *** solubility c_(∞) of particles is usually very small at low temperature,and there is obvious solubility only when the temperature reaches 600 *** surface energies E_(sur) of AI_(3)RE compounds and Al solid solution are respectively larger and smaller than that of pure Al,respectively,except for the surface(001) and(110) of Al_(3)*** all planes,with the increase of atomic number of RE,E_(sur) decreases firstly from Sc to La,and then increases linearly to *** results are helpful for designing high performance heat-resistance Al alloys.

关键词： First-principles calculations Diffusion rate Quasi-harmonic approximation Particle nucleation and growth Rare earths

Evaluation of the biodegradation product layer on Mg-1Zn alloy during dynamical strain

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Journal of Magnesium and Alloys 2021年第5期9卷 1842-1855页

作者： Lianxi chen cheng Guo Carsten Blawert Junjie Yang dongchu chen Xiaojian Wang Zhentao Yu Mikhail L.Zheludkevich Wei Li School of Materials Science and Hydrogen Energy Foshan UniversityFoshanGuangdong 528000China Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China Institute of Surface Science Helmholtz-Zentrum HereonGeesthacht 21502Germany College of Mechatronics and Control Engineering Shenzhen UniversityShenzhen 518060China

Magnesium(Mg)alloys are attractive biodegradable implant *** degradation products on Mg alloys play a critical role in the stability of the interface between implant and surrounding *** the present study,the effects of dynamic deformation on the interface layer of biomedical Mg-1Zn alloy were investigated using the constant extension rate tensile tests(CERT)coupled with electrochemical impedance spectroscopy(EIS).The deformation of the Mg-1Zn alloy had an adverse influence on the impedance of the surface degradation layer formed in simulated body fluid that only containing inorganic ***,the surface degradation layer with improved corrosion resistance was obtained for the strained samples tested in protein-containing simulated body *** spontaneous or enhanced adsorption of protein into the degradation product led to a flexible and stable hybrid anti-corrosive layer.A relationship between the dynamic deformation of Mg alloy and the impendence of the degradation layer was established,which demonstrates the necessity for in situ characterisation of the evolution of the surface layer under dynamic condition.

关键词： Degradation layer Protein Biodegradable Mg alloy Dynamic deformation Impedance

Recent advances in the synthesis of monolithic metal–organic frameworks

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Science China Materials 2021年第6期64卷 1305-1319页

作者： Chongxiong Duan Yi Yu Jingjing Li Libo Li Bichun Huang dongchu chen Hongxia Xi School of Materials Science and Hydrogen Engineering Foshan UniversityFoshan 528231China School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510640China Guangdong Key Laboratory for Hydrogen Energy Technologies Foshan 528000China School of Environment and Energy South China University of TechnologyGuangzhou 510006China

Although considerable achievements have been realized in recent years with respect to the syntheses of metal–organic frameworks(MOFs),majority of the developed MOFs are in the form of polydisperse microcrystalline powders,which cause dustiness,abrasion,and clogging and decrease pressure when used in industrial *** MOFs overcome these drawbacks and exhibit various promising *** this review,we present the recent advances associated with monolithic MOFs based on metal centers and a brief outline of the most prominent ***,the challenges and prospects associated with monolithic MOFs in terms of large-scale production and engineering applicability are analyzed based on our knowledge to conclude this review.

关键词： metal-organic frameworks monolithic structure synthetic strategies industrial practicability