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Journal of Materials Science & Technology 2022年第15期110卷 227-238页

作者： Pengfei Ji Bohan Chen Shuguang liu Bo Li Chaoqun Xia Xinyu Zhang Mingzhen Ma riping liu State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China School of Materials Science and Engineering Research Institute for Energy Equipment MaterialsHebei University of TechnologyTianjin 300130China Beijing Chunlizhengda Medical Instruments Co. Ltd.Beijing 101112China

Excellent comprehensive mechanical properties and corrosion resistance of TiZrNb equiatomic ratio medium-entropy alloy were obtained through recrystallization and spinodal decomposition.In addition to solid solution strengthening and recrystallization,the excellent mechanical properties can also be attributed to the hindering effect of nanoprecipitation formed via spinodal decomposition on the movement of dislocations.The high atomic arrangement density due to spinodal decomposition reduces the surface energy of the alloy passivation film,thereby increasing the activation energy of dissolution and the bonding energy between atoms,which improve the corrosion resistance and stability of the alloy passivation film.This work provides a new strategy to control the mechanical properties and corrosion resistance by combining recrystallization and spinodal decomposition.

关键词： Titanium Zirconium Mechanical properties Corrosion resistance Passive films

Anchoring Mo on C_(9)N_(4) monolayers as an efficient single atom catalyst for nitrogen fixation

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Journal of Energy Chemistry 2021年第6期30卷 443-450,I0011页

作者： Zhe Xue Xinyu Zhang Jiaqian Qin riping liu State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004HebeiChina Metallurgy and Materials Science Research Institute Chulalongkorn UniversityBangkok 10330Thailand

Electrochemical nitrogen fixation via a convenient and sustainable manner,exhibits an intriguing prospect for ammonia generation under ambient conditions.Currently,the design and development of high-efficiency and low-cost electrocatalysts remains the major challenge confronting nitrogen reduction reaction(NRR).Herein,anchoring the single Mo atom on the C_(9)N_(4) substrate(Mo@C_(9)N_(4)) to form an efficient single-atom catalyst(SAC) is proposed for the conversion of N2 to NH3.By employing density functional theory(DFT) calculations,we demonstrated that gas phase N2 can be sufficiently activated and efficiently reduced to NH3 on the surface of Mo@C_(9)N_(4).Meanwhile,we found that the NRR dominantly occurred on the Mo center via a preferred distal pathway with favorable limiting potential of 0.40 V.Importantly,the as-established Mo@C_(9)N_(4) catalyst exhibits an outstanding structural stability and good selectivity toward NRR.These findings provide a promising platform for designing Mo-based SACs for electrochemical N2 fixation.

关键词： Carbon nitride covalent compounds Electrochemical nitrogen reduction Single-atom catalyst Ammonia synthesis First-principles calculations

Hot Deformation Behaviour of SiC/AA6061 Composites Prepared by Spark Plasma Sintering

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Journal of Materials Science & Technology 2016年第4期32卷 291-297页

作者： Xiaopu Li Chongyu liu Kun Luo Mingzhen Ma riping liu State Key Laboratory of Metastable Materials Science and Technology Yanshan University Key Laboratory of New Processing Technology for Nonferrous Metal & Materials Ministry of Education Guilin University of Technology Guangxi Key Laboratory of Universities for Clean Metallurgy and Comprehensive Utilization of Nonferrous Metal Resources Guilin University of Technology

In this study, SiC/AA6061 composites with different SiC volume fractions （5%, 10%, 15% and 20%） were fabricated by spark plasma sintering. The deformation behaviour of the composites was studied by uni- axial compression test at temperatures from 573 K to 773 K and strain rates between 0.001 s^-1 and 1 s^-1. Results indicate that the flow stress of SiCIAA6061 composites increases with the increase of SiC volume fraction, with the decrease of deformation temperature and with the decrease of strain rate. The main deformation mechanism of the composites is dynamic recrystallisation （DRX）, and the DRX degree depends on the processing parameters of deformation. Higher SiC volume fraction, higher deformation temper- ature and lower deformation strain rate promote the occurrence of DRX. The strain rate sensitivity and deformation activation energy of SiC/AA6061 composites are calculated. Results show that with the in- crease in deformation temperature and the decrease in SiC volume fraction, the strain rate sensitivity of the composites increases. From 573 K to 773 K, the average deformation activation energy of 5vol.%SiC/ AA6061, 10voI.%SiC/AA6061, 15voI.%SiC/AA6061 and 20vol.%SiC/AA6061 are 20Z91, 230.88, 237.7 and 249.87 kJ mol^-1, respectively. The optimum hot working zone of the SiC/AA6061 composites is in the tem- perature range of 723 K to 773 K at strain rates from 0.1 s^-1 to 1 s^-1.

关键词： Spark plasma sinteringHot deformationAI alloy matrix composites

TMN4 complex embedded graphene as bifunctional electrocatalysts for high efficiency OER/ORR

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Journal of Energy Chemistry 2021年第4期30卷 437-443页

Developing highly active bifunctional electrocatalysts for oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)is of great significance in energy conversion and storage technologies.In this study,we systematically investigated the OER/ORR electrocatalytic activity of TMN_(4)@G system by using density functional theory(DFT)calculations.Globally,IrN_(4)@G is a very promising bifunctional catalyst for both OER and ORR with the extremely low overpotentials of 0.30 and 0.26 V,respectively.Such outstanding electrocatalytic performance is mainly attributed to the synergistic effect of Ir and N.More importantly,by constructing 2D activity volcano plots,we obtained the limiting overpotentials of TMN_(4)@G system with the values of 0.26 V for OER and 0.24 V for ORR.These findings open up new opportunities for further exploring graphene-based materials for highly efficient OER/ORR electrocatalysts.

关键词： N-doped graphene Transition Metal-N4 cluster First-principles calculations Oxygen evolution reaction Oxygen reduction reaction

In-situ TiC_P/Al Composites Prepared by TE/QP Method

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Journal of Materials Science & Technology 2005年第5期21卷 652-656页

作者： Mingzhen MA riping liu Hongli ZHAO Yifa YU Key Laboratory of Metastable Materials Science & Technology Yanshan University Qinhuangdao 066004 China Hengdian Group Xinna Electronic Co. LTD Dongyang 322118 China

An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents and the microstructure of the composites and the particle size of the reinforcement were analysed using X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results have shown that TiCp/Al composite with 40～70 vol. pct TiC particle reinforcement and high relative density can be directly obtained by TE/QP. TiC is the only reaction product when Al content in Al-Ti-C system is no more than 60 vol. pct, but Al3Ti phase will also form when Al content is more than 60 vol. pct. Increasing Al content prolongs the initial reaction time, reduces the highest reaction temperature and the reaction rate, and decreases the size of TiC particles. In addition, the microstructure of TiCp/Al composite and the structure of interface between TiCp and Al are studied using SEM and transmission electron microscopy （TEM）. The results show that the in-situ synthesized TiC particle has fcc cubic structure. The orientation between TiC particles and Al matrix can be described as （220）Al//（022）TiC and [112]Al//[011]TiC. Results of the mechanical property tests reveal that the ultimate strength （σ） and modulus （E） are 687 MPa and 142 GPa respectively when the Al content is 40 vol. pct. On contrary, 6 elongation increases by 3.2% with increasing Al content.

关键词： TiCp/Al composites Thermal explosion/quick pressure method （TE/QP） Microstructure Phase constituents Structure of interface Mechanical properties

Controlling the strength of Zr(10 1 2) grain boundary by nonmetallic impurities doping: A DFT study

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Journal of Materials Science & Technology 2020年第1期36卷 140-148页

作者： Zhe Xue Xinyu Zhang Jiaqian Qin Mingzhen Ma riping liu State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China Metallurgy and Materials Science Research Institute Chulalongkorn UniversityBangkok 10330Thailand

Impurity segregation even small amounts,can drastically change the cohesive properties of the grain boundaries(GB),eventually leading to intergranular embrittlement and failure of the materials,thereby effectively controlling the types and the concentrations of the impurity is very important.In this work,the nonmetallic impurities(C,H,O,N) segregation and their effects on the strength of Zr(10 1 2) GB were thoroughly investigated using first-principles calculations based on density functional theory.A comprehensive analysis of the interstitial configurations and the relative site energies indicating that C,N and O overwhelmingly prefer the octahedral sites,only H,prefers to reside in the tetrahedral sites.Moreover,the strengthening/embrittlement potency of impurity atoms on the GB was estimated using both the Rice-Wang model and first-principles tensile test calculations.The results show that all impurities,exhibit a strong segregation tendency near the GB region.The segregation of C,N and O has a remarkable strengthening effect on strength of the GB,whereas the presence of impurity H weaken the GB.Most importantly,the underlying mechanism of the strength change of the GBs due to the segregation of impurities was profoundly discussed by charge density and the bond lengths analyses,revealing that the strengthening effect especially for C-doped GB,mainly comes from an enhancement of the charge density across the GB plane.In the end,we expect that our results will be certainly useful for future theoretical and experimental investigations on Zr and its alloys.

关键词： Grain boundary Impurity segregation Strengthening Embrittlement First-principles calculations

Effectiveness and safety of acupuncture in treatment of pregnancyrelated symptoms:a systematic review and Meta-analysis

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Journal of Traditional Chinese Medicine 2024年第1期44卷 16-26页

作者： liu Tingting liu Tongou liu Mingfu School of Traditional Chinese Medicine Clinical Medicine Hubei University of Traditional Chinese MedicineWuhan 430000China First Clinical College of Hubei University of Traditional Chinese Medicine Wuhan 430000China Department of Acupuncture and Tuina Affiliated Hospital of Hubei University of Traditional Chinese MedicineHubei Provincial Hospital of Traditional Chinese MedicineWuhan 430000China

OBJECTIVE:To systematically evaluate the efficacy and safety of acupuncture(AM)in the treatment of pregnancyrelated symptoms such as acute vomiting during pregnancy.METHODS:We comprehensively searched the available literature up to November 2021,including Pub Med,Embase,Cochrane Library,Chinese Biomedical Literature Database,and China National Knowledge Infrastructure Database,for randomized controlled trials(RCTs)on AM for the treatment of severe vomiting,insomnia,pharyngeal and pelvic pain,mood abnormalities,and dyspepsia during pregnancy.RESULTS:Sixteen RCTs with a cumulative sample size of 1178 cases were included.Of these,964 patients were included in the Meta-analysis.The Meta-analysis results showed that AM was more efficient than Western medicine in treating discomfort during pregnancy[odds ratio(OR)=1.19,95%confidence interval(CI)(1.11,1.28),P<0.01].AM was better than the control group in improving the visual analog scale scores[standard mean difference(SMD)=0.62,95%CI(0.53,0.71),P<0.01].AM was superior to the control group in improving Numerical Rating Scale(NRS)symptom scores[OR=7.31,95%CI(3.36,15.94),P<0.01].There was no significant difference in adverse effects between the AM and sham-AM groups and the analgesic drug group[OR=0.70,95%CI(0.39,1.28),P=0.25],but the treatment and control groups had mild adverse effects with a low incidence.CONCLUSIONS:AM is more effective than other treatments or pharmacotherapy alone in the treatment of pregnancy-related symptoms,and is relatively safe.However,the quality of the included trials was rather poor,and high-quality studies are required to confirm our findings.

关键词： acupuncture pregnancy nausea vomiting sleep initiation and maintenance disorders low back pain pelvic pain mood abnormalities Meta-analysis systematic review

Removal of Cr(Ⅵ)by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron:Synthesis,mechanism,and longevity

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Journal of Environmental Sciences 2024年第8期142卷 115-128页

作者： Yijun Duan Fang liu Xiang liu Miao Li School of Environment Tsinghua UniversityBeijing 100084China Transportation Institute of Inner Mongolia University Hohhot 010070China

Microscale zero-valent iron(mZVI)has shown great potential for groundwater Cr(Ⅵ)remediation.However,low Cr(Ⅵ)removal capacity caused by passivation restricted the wide use of mZVI.We prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehydecrosslinked chitosan matrix,and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron particles.The average pore diameter of mZVI/GCS was 8.775 nm,which confirmed the mesoporous characteristic of this material.Results of batch experiments demonstrated that mZVI/GCS exhibited high Cr(Ⅵ)removal efficiency in a wide range of pH(2-10)and temperature(5-35℃).Common groundwater coexisting ions slightly affected m ZVI/GCS.The material showed great reusability,and the average Cr(Ⅵ)removal efficiency was 90.41%during eight cycles.In this study,we also conducted kinetics and isotherms analysis.Pseudo-second-order model was the most matched kinetics model.The Cr(Ⅵ)adsorption process was fitted by both Langmuir and Freundlich isotherms models,and the maximum Langmuir adsorption capacity of m ZVI/GCS reached243.63 mg/g,which is higher than the adsorption capacities of materials reported in most of the previous studies.Notably,the column capacity for Cr(Ⅵ)removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day experiment.Therefore,mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(Ⅵ)remediation material with practical application prospects.

关键词： Chitosan Glutaraldehyde mZVI Cr(Ⅵ) Groundwater

Hot deformation behavior of 51.1Zr–40.2Ti–4.5Al–4.2V alloy in the single β phase field

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Progress in Natural Science:Materials International 2015年第1期25卷 34-41页

作者： Jingli Duan Yuanbiao Tan Liyuan Ji Wenchang liu Jingwu Zhang riping liu Key Laboratory of Metastable Materials Science and Technology College of Materials Science and Engineering Yanshan University

The hot deformation behavior of a newly developed 51.1Zr–40.2Ti–4.5Al–4.2 V alloy was investigated by compression tests in the deformation temperature range from 800 to 1050 ℃ and strain rate range from 10-3to 100 s-1. At low temperatures and high strain rates, the flow curves exhibited a pronounced stress drop at the very beginning of deformation, followed by a slow decrease in flow stress with increasing strain. The magnitude of the stress drop increased with decreasing deformation temperature and increasing strain rate. At high temperatures and low strain rates, the flow curves exhibited typical characteristics of dynamic recrystallization. A hyperbolic-sine Arrhenius-type equation was used to characterize the dependences of the flow stress on deformation temperature and strain rate. The activation energy for hot deformation decreased slightly with increasing strain and then tended to be a constant value. A microstructural mechanism map was presented to help visualize the microstructure of this alloy under different deformation conditions.

关键词： 51.1Zr–40.2Ti–4.5Al–4.2V alloy Hot deformation Microstructure Dynamic recovery Dynamic recrystallization

Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu liu Chongru liu North China Electric Power University Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC system.However,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC system.Moreover,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is high.Thus,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind farms.The simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed