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Simultaneously enhancing the strength and ductility of as-extruded AlN/AZ91 composites via nano-precipitation and pyramidal slip

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Journal of Materials Science & Technology 2024年第5期172卷 240-254页

作者： Bin Zhang Yunxia Sun Tuo Liang Yunzhen Li Tian Li Jingchao Wang Ruiru Cai Changlin Yang state key laboratory of Solidification processing Northwestern Polytechnical UniversityXi’an 710072China

Age hardening is often used to optimize the mechanical properties of as-deformed Mg-based materials in industry,whereas the improvement of strength is usually accompanied by the significant loss of ductility,which hinders the application of Mg-based materials in structural *** the present work,high strength-ductility synergy(the yield strength of 263±9 MPa,ultimate tensile strength of 398±7 MPa and elongation to fracture of 34%±1%)was realized in as-extruded AlN/AZ91 composites after optimiz-ing aging *** characterization shows that AlN particles induced a large number of geometrically necessary dislocations around the AlN/Mg interface during extrusion,which decreased the nucleation barrier and provided more heterogeneous nucleation sites forγ-Mg 17 Al 12 continuous ***,95%of residual dislocations in as-extruded AlN/AZ91 composites were annihilated dur-ing peak-aging,suppressing the growth and coarsening of continuous ***,high density of nano-sizedγ-Mg 17 Al 12 continuous precipitates was produced in as-extruded AlN/AZ91 composites af-ter *** tension,gliding dislocations bypassed sphericalγ-Mg 17 Al 12 nano-precipitates by Orowan looping rather than cutting mechanism,which induced a strong block on dislocation *** high yield strength was mainly attributed to the high density of non-shearableγ-Mg 17 Al 12 nano-precipitates with spherical morphology,which was different from other Mg-Al-based *** results of texture evolution and slip trace analysis demonstrated that the suppression of extension twinning and less basal slip was due to the enhanced activity of pyramidalc+aslip in as-extruded AlN/AZ91 com-posites after peak-aging during the room temperature tension,meanwhile,the dislocation density of as-extruded AlN/AZ91 composites was significantly decreased during peak-aging,then higher elongation to fracture was achieved.

关键词： Magnesium matrix composites Mechanical properties Precipitation Deformation mechanisms Non-basal slip

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Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process

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Petroleum Science 2024年第3期21卷 2112-2119页

作者： Yu-Guo Li Chen He Chun-Mao Chen Fan Liu Quan Shi state key laboratory of Heavy Oil processing China University of Petroleum state key laboratory of Coal Mining and Clean Utilization PetroChina Ningxia Petrochemical Company

Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD) and organic sulfur contents. Even after the recovery of H2S from the sour water by the stripping process, the effluent still contains a high concentration of dissolved organic sulfur(DOS), which can have a huge bad influence. While chemical composition of dissolved organic matter(DOM) in refinery wastewater has been extensively studied, the investigation of recalcitrant DOS from sour waters remains unclear. In the present study, chemical composition of sour water DOMs(especially DOS) was investigated using fluorescence spectroscopy(excitation-emission matrix, EEM) and mass spectrometry,including gas chromatography-mass spectrometry(GC-MS) and high-resolution Orbitrap MS. The GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process, while compounds with high hydrophilicity and humification degree were found to be more recalcitrant. The Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated compounds. However, the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms, particularly in the form of highly unsaturated and aromatic compounds. The Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates, disulfide bonds, thioethers. Understanding the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment.

关键词： Molecular transformation Dissolved organic sulfur Stripping process Refinery sour water Orbitrap MS

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Control of interfacial reaction and defect formation in Gd/Bi_(2)Te_(2.7)Se_(0.3)composites with excellent thermoelectric and magnetocaloric properties

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Chinese Physics B 2024年第8期33卷 474-481页

作者：薛天畅魏平刘承姗李龙舟朱婉婷聂晓蕾赵文俞 state key laboratory of Advanced Technology for Materials Synthesis and processing Wuhan University of TechnologyWuhan 430070China

The method to combine thermoelectric(TE)and magnetocaloric(MC)cooling techniques lies in developing a new material that simultaneously possesses a large TE and good MC cooling *** this work,using n-type Bi_(2)Te_(2.7)Se_(0.3)(BTS)as the TE base material and Gd as the second-phase MC material,Gd/BTS composites were prepared by the spark plasma sintering *** the composites,interfacial reaction between Gd and BTS was identified,resulting in the formation of Gd Te,which has a large impact on the electron concentration through the adjustment of defect *** MC/TE composite containing 2.5 wt%Gd exhibited a ZT value of 0.6 at 300 K,essentially retaining the original TE performance,while all the composites largely maintained the excellent MC performance of *** work provides a potential pathway to achieving high performance in MC/TE composites.

关键词： thermo-electro-magnetic energy conversion materials interfacial reaction thermoelectric performance magnetic entropy change

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Effect of Molecular Weight on Thermoelectric Performance of P3HT Analogues with 2-Propoxyethyl Side Chains

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 268-281页

作者：董得福 WANG Wei ZHAN Chun LI Chenglong ZHOU Qisheng 肖生强 state key laboratory of Advanced Technology for Materials Synthesis and processing Wuhan University of TechnologyWuhan 430070China

By replacing hexyl chains in poly(3-hexylthiophene)(P3HT)with 2-propoxyethyls,four poly(3-(2-propoxyethyl)thiophene)(P3POET)homopolymers with comparable polydispersity indexes(PDI)and regioregularities were prepared herein in addition with step increment of about 7 kDa on numberaverage molecular weight(M_(n))from around 11 to 32 kDa(accordingly denoted as P11k,P18k,P25k,and P32k).When doped in film by FeCl_(3)at the optimized conditions,the maximum power factor(PF_(max))increases greatly from 4.3μW·m^(-1)·K^(-2)for P11k to 8.8μW·m^(-1)·K^(-2)for P18k,and further to 9.7μW·m^(-1)·K^(-2)for P25k,followed by a slight decrease to 9.2μW·m^(-1)·K^(-2)for *** close Seebeck coefficients(S)at PF_(max)are observed in these doped polymer films due to their consistent frontier orbital energy levels and Fermi *** main contribution to this PF_(max)evolution thus comes from the corresponding conductivities(σ).Theσvariation of the doped films can be rationally correlated with their microstructure evolution.

关键词： conjugated polymer molecular weight microstructure thermoelectric performance

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Low-concentration and multi-component NMHCs capture from oil field exhaust using porous ZIF-8/iso-hexadecane slurry

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Green Chemical Engineering 2024年第2期5卷 245-256页

作者： Kun Li Han Tang Jin Cai Chun Deng Bei Liu Yunlei Peng Changyu Sun Guangjin Chen state key laboratory of Heavy Oil processing China University of PetroleumBeijing102249China

Non-methane hydrocarbons(NMHCs)are a common type of volatile organic compounds(VOCs)pollutant in the petrochemical industry and have attracted widespread attention because of their adverse health effects and environmental *** this paper,we report a new porous slurry formed with zeolitic imidazolate framework-8(ZIF-8)and iso-hexadecane to capture the low-concentration and multi-component NMHCs(mainly ethane(C_(2)H_(6)),propane(C_(3)H_(8)),and n-butane(n-C_(4)H_(10)))from the oil field *** sorption capacity of C_(2)H_(6)in the slurry is significantly higher than that of nitrogen(N_(2))and methane(CH_(4)).Moreover,the slurry demonstrated a clear advantage for C_(2)H_(6)over N_(2)and CH_(4)in competitive adsorption through the pressure-drop *** the NMHCs capture experiments,the C_(3)H_(8)and n-C_(4)H_(10)concentrations after purification can be reduced to below 100 ppm,while the C_(2)H_(6)concentration can reach approximately 180 *** encouragingly,in the breakthrough tests,the slurry exhibits a perfect kinetic separation selectivity for multi-component ***,to avoid structural collapse of ZIF-8 material during long-term use in acidic and wet environments,a certain amount of 2-methylimidazole was retained in the slurry as a protective agent in the material synthesis *** this way,the ZIF-8 materials in the slurry can retain the stable characteristic structure in an aqueous and acidic environment and keep the capture capacity for NMHCs without *** believe the porous ZIF-8/iso-hexadecane slurry is a promising capture agent for low-concentration and multi-component NMHCs with strong purification capacity and stability.

关键词： VOCs capture NMHCs capture MOFs ZIF-8 Porous slurry

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Microstructure Regulation and Combustion Performance Optimization of PVDF/Al Composite Powder by Non-covalent Functionalized Graphenes

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 904-911页

作者：易卓然 DENG Haoyuan QIN Mei 孙一 LUO Guoqiang state key laboratory of Advanced Technology for Materials Synthesis and processing Wuhan University of TechnologyWuhan 430070China

Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer *** regulation rule of SPG with different contents on the energy release of fluorine-containing system was *** the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4845.28 kPa and 8683.58 kPa/*** the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/*** the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.

关键词： energetic materials PVDF/Al composites graphene modification energy release combustion

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Metal–organic framework wafer enabled fast response radiation detection with ultra-low dark current

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Nano Research 2024年第4期17卷 2988-2993页

作者： Meng Xu Jianxi Liu Wei Wu Yang Chen Donghao Ma Sixin Chen Wanqi Jie Menghua Zhu Yadong Xu state key laboratory of Solidification processing MIIT Key Laboratory of Radiation Detection Materials and Devices&School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

Semiconductive metal–organic frameworks(MOFs)have attracted great interest for the electronic ***,dark currents of present hybrid organic–inorganic materials are 1000–10,000 times higher than those of commercial inorganic detectors,leading to poor charge ***,we demonstrate a ZIF-8(Zn(mim)_(2),mim=2-methylimidazolate)wafer with ultra-low dark current of 1.27 pA·mm^(-2) under high electric fields of 322 V·mm^(-1).The isostatic pressing preparation process provides ZIF-8 wafers with good ***,the presence of redox-active metals and small spatial separation between components promotes the charge *** ZIF-8-based semiconductor detector shows promising X-ray detection sensitivity of 70.82μC·Gy^(-1)·cm^(-2) with low doses exposures,contributing to superior X-ray imaging capability with a relatively high spatial resolution of 1.2 lp·mm^(-1).Simultaneously,good peak discrimination with the energy resolution of~43.78%is disclosed when the detector is illuminated by uncollimated 241Am@5.48 MeVα-*** results provide a broad prospect of MOFs for future radiation detection applications.

关键词： MOFs lead-free α-particles X-ray detection and imaging dark current fast response

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Synergistic effects and kinetics analysis for co-pyrolysis of vacuum residue and plastics

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 71-81页

作者： Chao Wang Xiaogang Shi Aijun Duan Xingying Lan Jinsen Gao Qingang Xiong state key laboratory of Heavy Oil processing China University of Petroleum-BeijingBeijing 102249China state key laboratory of Pulp and Paper Engineering South China University of TechnologyGuangzhou 510640China

This study utilizedathermogravimetric analyzer to assess the thermal decomposition behaviors and kinetics properties of vacuum residue(VR)and low-density polyethylene(LDPE)*** kinetic parameters were calculated using the Friedman *** demonstrate the interactive effects between LDPE and VR during the co-pyrolysis process,the disparity in mass loss and mass loss rate between the experimental and calculated values was *** co-pyrolysis curves obtained through estimation and experimentation exhibited significantdeviations,whichwerei influencedby temperature and mixing ratio.A negative synergistic interaction was observed between LDPE and VR,although this inhibitory effect could be mitigated or eliminated by reducing the LDPE ratio in the mixture and increasing the ***-pyrolysisprocess resulted in a reduction in carbon residue,which could be attributed to the interaction between LDPE and the heavy fractions,particularly resin and asphaltene,present in *** findings align with the pyrolysis behaviors exhibited by the four VR ***,it was observed that the co-pyrolysis process exhibited lower activation energy as the VR ratio increased,indicating a continuous enhancement in the reactivity of the mixed samples during co-pyrolysis.

关键词： co-pyrolysis heavy residual oil polyethylene thermogravimetric analysis synergistic effects

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Fabrication of highly effective electrodes for iron chromium redox flow battery

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Nano Research 2024年第5期17卷 3988-3996页

作者： Yingchun Niu Chao Guo Yinping Liu Guangfu Wu Tianhang Zhou Fangang Qu Ziji Yang Ali Heydari Chunming Xu Quan Xu state key laboratory of Heavy Oil processing China University of Petroleum(Beijing)Beijing 102249China

Iron-chromium redox flow batteries(ICRFBs)have emerged as promising energy storage devices due to their safety,environmental protection,and reliable *** carbon cloth(CC),often used in ICRFBs as the electrode,provides a suitable platform for electrochemical processes owing to its high surface area and interconnected porous ***,the CC electrodes have issues,such as,insufficient electron transfer performance,which limits their industrial ***,we employed silicic acid etching to carve dense nano-porous structures on the surface of CC electrodes based on the favorable design of ICRFBs and the fundamental principles of electrode polarization *** a result,we developed a multifunctional carbon cloth electrode with abundant vacancies,notably enhancing the performance of the *** fabricated electrode showcased a wealth of defect sites and superior electronic transport properties,offering an extensive and effective reaction area for rapidly flowing *** an electrode compression ratio of 40%and the highest current density in ICRFBs so far(140 mA·cm^(-2)),the battery achieved the average energy efficiency of 81.3%,11.24%enhancement over the previously published ***,throughout 100 charge-discharge cycles,the average energy efficiency degradation was negligible(~0.04%),which has the potential to become the most promising candidate for large-scale and long-term electrochemical energy storage applications.

关键词： iron chromium redox flow battery electron carbon cloth defect site density functional theory(DFT)calculation

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Tuning the surface electronic structure of noble metal aerogels to promote the electrocatalytic oxygen reduction

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Journal of Energy Chemistry 2024年第2期89卷 557-564,I0013页

作者： Hongxing Yuan Wei Gao Xinhao Wan Jianqi Ye Dan Wen state key laboratory of Solidification processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072ShaanxiChina

The sluggish kinetics of the oxygen reduction reaction(ORR)is the bottleneck for various electrochemical energy conversion *** the electronic structure of electrocatalysts by ligands has received particular attention in deriving valid ORR ***,the surface electronic structure of Ptbased noble metal aerogels(NMAs)was modulated by various organic ligands,among which the electron-withdrawing ligand of 4-methylphenylene effectively boosted the ORR *** calculations suggested the smaller energy barrier for the transformation of O^(*) to OH^(*) and downshift the d-band center of Pt due to the interaction between 4-methylphenylene and the surface metals,thus enhancing the ORR intrinsic *** Pt3Ni and Pt Pd aerogels with 4-methylphenylene decoration performed significant enhancement in ORR activity and durability in different ***,the 4-methylphenylene modified Pt Pd aerogel exhibited the higher halfwave potential of 0.952 V and the mass activity of 10.2 times of commercial Pt/*** work explained the effect of electronic structure on ORR electrocatalytic properties and would promote functionalized NMAs as efficient ORR electrocatalysts.

关键词： Noble metal aerogels Surface electronic structure ORR Electrocatalyst Organic ligands

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