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Sequestration of helium and xenon via iron-halide compounds in early Earth

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Matter and Radiation at Extremes 2024年第3期9卷 83-88页

作者： Jurong Zhang Hanyu Liu Changfeng Chen Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education and State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China School of Physics and Electronics Shandong Normal UniversityJinan 250014China International Center of Future Science Jilin UniversityChangchun 130012China Department of Physics and Astronomy University of NevadaLas VegasNevada 89154USA

The terrestrial abundance anomalies of helium and xenon suggest the presence of deep-Earth reservoirs of these elements,which has led to great interest in searching for materials that can host these usually unreactive elements.Here,using an advanced crystal structure search approach in conjunction with first-principles calculations,we show that several Xe/He-bearing iron halides are thermodynamically stable in a broad region of P–T phase space below 60 GPa.Our results present a compelling case for sequestration of He and Xe in the early Earth and may suggest their much wider distribution in the present Earth than previously believed.These findings offer insights into key material-based and physical mechanisms for elucidating major geological phenomena.

关键词： halide searching insight

Improvement of hydrogen permeation barrier performance by iron sulphide surface films

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International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1792-1800页

作者： Pengpeng Bai Shaowei Li Jie cheng Xiangli Wen Shuqi Zheng Changfeng Chen Yu Tian State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China School of Mechanical Electronic&Information Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China

Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the barrier effect of different Fe–S films on hydrogen permeation was tested using electrochemical hydrogen permeation method. After that, the electrical properties of Fe–S compound during phase transformation were measured using thermoelectric measurement system. Results show that the mackinawite has no obvious barrier effect on hydrogen penetration, as a p-type semiconductor, and pyrrhotite (including troilite) has obvious barrier effect on hydrogen penetration,as an n-type semiconductor. Hydrogen permeation tests showed peak permeation performance when the surface was deposited with a continuous film of pyrrhotite (Fe_(1–x)S) and troilite. The FeS compounds suppressed hydrogen permeation by the promotion of the hydrogen evolution reaction, semiconducting inversion from p-to n-type, and the migration of ions at the interface.

关键词： hydrogen permeation barrier iron sulfide pyrrhotite semiconductor

Heterogeneously supported pseudo-single atom Pt as sustainable hydrosilylation catalyst

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Nano Research 2018年第5期11卷 2544-2552页

作者： Huachao Zai Yizhou Zhao Shanyu chen Lei Ge Changfeng Chen Qi chen Yujing Li State Key Laboratory of Heavy Oil Department of Materials Science and Engineering College of Science China University of Petroleum Beijing 102249 China Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications School of Materials Science and Engineering Beijing Institute of Technology Beijing 100081 China

The identification of highly active heterogeneous catalysts to replace their homogeneous counterparts remains a challenge in the case of organic catalysts, especially polymers, in highly viscous reaction systems. In this work, we designed and synthesized a novel, solid-supported, and heterogeneous pseudo-single atom Pt catalyst with high activity and recyclability. Superparamagnetic Fe3O4-SiO2 core--shell nanoparticles （NPs） were used as the substrate. The functionalization of the SiO2 shell with silane coupling agents containing vinyl groups allows stabilizing Pt on the SiO2 surface through complexation. The as-prepared pseudosingle atom Pt displays high activity in the hydrosilylation of allyl-terminated polyether with polymethylhydrosiloxane and could be easily collected by applying a magnetic field. The Pt/vinyl/SiO2/Fe3O4 catalyst can be reused for up to four reaction cycles without appreciable decrease in activity. This work demonstrates a novel strategy for the design of pseudo-single atom noble metal catalysts for processes in high-viscosity media.

关键词： hydrosilylation,superparamagnetic,core-shell catalyst,single-atom catalyst,recyclable catalyst

Surface defect-rich ceria quantum dots anchored on sulfur-doped carbon nitride nanotubes with enhanced charge separation for solar hydrogen production

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Journal of Energy Chemistry 2021年第1期30卷 51-59,I0003页

作者： Mengru Li Changfeng Chen Liping Xu Yushuai Jia Yan Liu Xin Liu Institute of Advanced Materials College of Chemistry and Chemical EngineeringJiangxi Normal UniversityNanchang 330022JiangxiChina

Designing defect-engineered semiconductor heterojunctions can effectively promote the charge carrier separation.Herein,novel ceria(CeO2) quantum dots(QDs) decorated sulfur-doped carbon nitride nanotubes(SCN NTs) were synthesized via a thermal polycondensation coupled in situ depositionprecipitation method without use of template or surfactant.The structure and morphology studies indicate that ultrafine CeO2 QDs are well distributed inside and outside of SCN NTs offering highly dispersed active sites and a large contact interface between two components.This leads to the promoted formation of rich Ce^(3+) ion and oxygen vacancies as confirmed by XPS.The photocatalytic performance can be facilely modulated by the content of CeO2 QDs introduced in SCN matrix while bare CeO2 does not show activity of hydrogen production.The optimal catalyst with 10% of CeO2 loading yields a hydrogen evolution rate of 2923.8 μmol h-1 g-1 under visible light,remarkably higher than that of bare SCN and their physical mixtures.Further studies reveal that the abundant surface defects and the created 0 D/1 D junctions play a critical role in improving the separation and transfer of charge carriers,leading to superior solar hydrogen production and good stability.

关键词： Photocatalytic hydrogen evolution Ceria quantum dots Sulfur-doped carbon nitride nanotubes Surface defects Charge separation

Corrosion behavior of Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) high-entropy alloy coating via 3D printing laser cladding in a sulphur environment

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Journal of Materials Science & Technology 2021年第1期60卷 197-205页

作者： Hongxia Wan Dongdong Song Xiaolei Shi Yong Cai Tingting Li Changfeng Chen Beijing Key Laboratory of Failure Corrosion and Protection of Oil/Gas Facility MaterialsDepartment of Materials Science and EngineeringChina University of Petroleum(Beijing)Beijing 102249China Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China

High-entropy alloys(HEAs) are of great interest in materials science and engineering communities owing to their unique phase structure.HEAs are constructed with five or more principal alloying elements in equimolar or near-equimolar ratios.Therefore,they can derive their performance from multiple principal elements ratherthan a single element.In this work,three-dimensional printing laser cladding was applied to produce an Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) HEA coating.The experimental results confirmed that the laser cladding could be used to produce a thin coating of 120 μm in thickness.In the high-temperature laser cladding process,some Fe elements diffused from the substrate to the coating,forming a combination of face-centred cubic and body-centred cubic phase structures.The HEA coating metallurgically bonded well with the substrate.Owing to the increased dislocation density and number of grain boundaries,the HEA coating was harder and had a stronger hydrophobicity than X70 steel.The electrochemistry results showed that the HEA coating had better corrosion resistance than X70 steel.Aluminium oxides formed on the surface of the HEA coating had a certain protective effect.However,because of the laser cladding,the HEA coating generated cracks.In future work,the laser cladding technology will be improved and heat treatment will be implemented to prevent formation of cracks.

关键词： High-entropy alloy coating(HEA coating) Laser cladding Corrosion behaviour

Solving Strength–Toughness Dilemma in Superhard Transition-Metal Diborides via a Distinct Chemically Tuned Solid Solution Approach

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Research 2023年第3期6卷 473-483页

作者： Xinlei Gu Chang Liu Xinxin Gao Kan Zhang Weitao Zheng Changfeng Chen State Key Laboratory of Superhard Materials Department of Materials Science and Key Laboratory of Automobile MaterialsMOEJilin UniversityChangchun 130012China International Center for Computational Methods&Software College of PhysicsJilin UniversityChangchun 130012China Department of Physics and Astronomy University of NevadaLas VegasNV 89154USA

Solid solution strengthening enhances hardness of metals by introducing solute atoms to create local distortions in base crystal lattice,which impedes dislocation motion and plastic deformation,leading to increased strength but reduced ductility and toughness.In sharp contrast,superhard materials comprising covalent bonds exhibit high strength but low toughness via a distinct mechanism dictated by brittle bond deformation,showcasing another prominent scenario of classic strength–toughness tradeoff dilemma.Solving this less explored and understood problem presents a formidable challenge that requires a viable strategy of tuning main load-bearing bonds in these strong but brittle materials to achieve concurrent enhancement of the peak stress and related strain range.Here,we demonstrate a chemically tuned solid solution approach that simultaneously enhances hardness and toughness of superhard transition-metal diboride Ta_(1−x)Zr_(x)B_(2).This striking phenomenon is achieved by introducing solute atom Zr that has lower electronegativity than solvent atom Ta to reduce the charge depletion on the main load-bearing B–B bonds during indentation,leading to prolonged deformation that gives rise to notably higher strain range and the corresponding peak stress.This finding highlights the crucial role of properly matched contrasting relative electronegativity of solute and solvent atoms in creating concurrent strengthening and toughening and opens a promising avenue for rational design of enhanced mechanical properties in a large class of transition-metal borides.This strategy of concurrent strength–toughness optimization via solute-atom-induced chemical tuning of the main load-bearing bonding charge is expected to work in broader classes of materials,such as nitrides and carbides.

关键词： toughness deformation strengthening

Electrochemical oxidative cyclization of alkenes,boronic acids,and dichalcogenides to access chalcogenated boronic esters and 1,3-diols

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Organic Chemistry Frontiers 2022年第1期9卷 12-18页

作者： changfeng Huang Jijing Hu Guangxian chen Minjian Wu Hua Cao Xiang Liu School of Chemistry and Chemical Engineering and Guangdong Cosmetics Engineering&Technology Research Center Guangdong Pharmaceutical UniversityZhongshan 528458China

A sustainable,environmentally benign electrochemical oxidative three-component cyclization of allylic alcohols,boronic acids,and dichalcogenides under metal-free and oxidant-free conditions has been developed,which provides an efficient approach for the formation of C–Se/S and C–O bonds together.A series of chalcogenated boronic esters were afforded with a broad substrate scope through a clean electrochemical system.The resulting chalcogenated cyclic boronic esters were easily converted to chalcogenated 1,3-diols in good yields under mild conditions.

关键词： conditions boron esters

Numerical Simulation Investigation on Parameter Optimization of Deep-Sea Mining Vehicles

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 365-377页

作者： Hongyun Wu Wei Liu Min Jiang changfeng Li Jiangming Li Bingzheng chen Chunlai Wang Yuheng chen Institute of Marine Research Changsha Mining Research Institute Co.Ltd.Changsha 410012China School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China School of Energy and Engineering China University of Mining&Technology BeijingBeijing 100083China

The four-track walking mining vehicle can better cope with the complex terrain of cobalt-rich crusts on the seabed.To explore the influence of different parameters on the obstacle-crossing ability of mining vehicles,this paper took a certain type of mine vehicle as an example and establish a mechanical model of the mine vehicle.Through this model,the vehicle's traction coefficient variation could be analyzed during the obstacle-crossing process.It also reflected the relationship between the obstacle-crossing ability and the required traction coefficient.Many parameters were used for this analysis including the radius of the guide wheel radius,ground clearance of the driving wheel,the dip angle of the approaching angular and the position of centroid.The result showed that the ability to cross the obstacles requires adhesion coefficient as support.When the ratio between obstacle height and ground clearance of the guide wheel was greater than 0.7,the required adhesion coefficient increased sharply.The ability to cross obstacles will decrease,if the radius of the guide wheel increases,the height of the driving wheel increases or the dip angle of the approaching angular increases.It was most beneficial to cross the obstacle when-the ratio of the distance between the center of mass and the front driving wheel to the wheelbase is between 0.450.48.The results of this paper could provide reference for structural parameter design and performance research for mining vehicles.

关键词： Rich crusts Four-track vehicles Triangular track Obstacle-crossing

Prediction of hot deformation behavior in Ni-based alloy considering the effect of initial microstructure

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Progress in Natural Science:Materials International 2015年第1期25卷 66-77页

作者： Qiang Zuo Feng Liu Lei Wang Changfeng Chen Zhonghua Zhang State Key Laboratory of Solidification Processing Northwestern Polytechnical University Department of Materials Science and Engineering China University of Petroleum Baoshan Iron & Steel Co. Ltd.

High temperature heat treatments were conducted for as-cast N08028 alloy to obtain various microstructures with different amounts of σ-phase,and then hot compression tests were carried out using Gleeble-3500 thermo-mechanical simulator in deformation temperature range from 1100 to1200 ℃ and strain rate range from 0.01 to 1 s-1. For the same initial microstructure, the flow stress was observed to increase with increasing the strain rate and decreasing the deformation temperature, while for the same deformation condition, the flow stress was found to increase with increasing the amount of σ-phase in the initial microstructure. Moreover, dynamic recrystallization was found to be the main dynamic soften mechanism. On this basis, Arrhenius-type constitutive equations and artificial neural network(ANN) model with back-propagation learning algorithm were established to predict hot deformation behavior of the alloy. Furthermore, the parameters of constitutive equations were found to be dependent on the initial microstructure, which was also as one of the inputs for the ANN model. Suitability of the two models was evaluated by comparing the accuracy, correlation coefficient and average absolute relative error, of the prediction. It is concluded that the ANN model is more accurately than the constitutive equations.

关键词： Initial microstructure Ni-based alloy Hot deformation behavior Constitutive equations Artificial neural network