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Segregation of Mg-6Gd alloy under natural convection:From macro solute distribution to micro dendrite growth

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China Foundry 2024年第5期21卷 613-624页

作者： Hong-xu Chen Ang Zhang Hao Li Yu Gao Yu-hong Cui Guang-sheng Huang Bin Jiang Fu-sheng Pan National engineering research center for Magnesium Alloys National Key Laboratory of Advanced Casting TechnologiesCollege of Materials Science and EngineeringChongqing UniversityChongqing 400044China

Segregation is a serious defect in alloy ingots which severely deteriorates materials *** segregation defect in Mg-6Gd alloy is studied by coupling macro thermal-solutal-convection transport and micro dendrite *** macroscopic fluid dynamics and mass transfer equations are resolved to forecast the segregation behavior under conditions of continuous temperature variation during the solidification *** numerical model is validated by testing double-diffusive natural convection in a closed square cavity.A phase field model is then applied to simulate the micro dendrite growth,using macro undercooling and liquid flow velocity as boundary *** show that the multiscale segregation behavior,including macro solute distribution and micro dendritic morphology,is strongly dependent on the temperature condition and the liquid convection,which provides guidance for reducing and eliminating the segregation defect.

关键词： magnesium alloy segregation numerical simulation phase-field simulation multiscale

Noncovalent cross-linked engineering hydrogel with low hysteresis and high sensitivity for flexible self-powered electronics

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Journal of Energy Chemistry 2024年第7期94卷 136-147页

作者： Hang Yuan Shaowei Han Jia Wei Songwei Li Peipei Yang Hao-Yang Mi Chuntai Liu Changyu Shen National engineering research center for Advanced Polymer Processing Technology Key Laboratory of Materials Processing and Mold(Ministry of Education)Zhengzhou UniversityZhengzhou450002HenanChina Yunnan TobaccoQuality Inspection&Supervision Station Kunming 650106YunnanChina

In this study,the hydrogel network was reinforced by covalent-like hydrogen bonding,and the strong binding ability of boron-nitrogen coordination served as the main driving *** them,acrylamide(AM)and 3-acrylamidophenylboronic acid(AAPBA)were the main body,and the numerous hydroxyl groups in the trehalose(Treh)molecule and other polymer groups formed strong hydrogen bonding interactions to improve the mechanical properties of the PAM/PAAPBA/Treh(PAAT)hydrogel and ensured the simplicity of the synthesis *** hydrogel possessed high strain at break(1239%),stress(64.7 kPa),low hysteresis(100%to 500%strain,corresponding to dissipation energy from 1.37 to 7.80 kJ/m^(3)),and outstanding cycling stability(retained more than 90%of maximum stress after 200 ten-sile cycles).By integrating carbon nanotubes(CNTs)into PAAT hydrogel(PAATC),the PAATC hydrogel with excellent strain response performance was successfully *** PAATC conductive hydro-gel exhibited high sensitivity(gauge factor(GF)=10.58 and sensitivity(S)=0.304 kPa^(-1)),wide strain response range(0.5%-1000%),fast response time(450 ms),and short recovery time(350 ms),excellent fatigue resistance,and strain response ***,the PAATC-based triboelectric nanogener-ator(TENG)displayed outstanding energy harvesting performance,which shows its potential for appli-cation in self-powered electronic devices.

关键词： Low hysteresis Covalent-like hydrogen bonding Boron-nitrogen coordination Hydrogel sensor Triboelectric nanogenerator

Design of Resilient Sensor Networks Balancing Resilience and Efficiency

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International Journal of Disaster Risk Science 2024年第1期15卷 107-115页

作者： Sergey N.Vecherin Kiril D.Ratmanski Luke Hogewood Igor Linkov Cold Regions research and engineering Laboratory Engineering Research and Development CenterHanoverNH 03755USA Environmental Laboratory Engineering Research and Development CenterVicksburgMS 39180USA

In recent years,the notion of resilience has been developed and applied in many technical areas,becoming exceptionally pertinent to disaster risk *** a disaster situation,accurate sensing information is the key to efficient recovery *** general,resilience aims to minimize the impact of disruptions to systems through the fast recovery of critical functionality,but resilient design may require redundancy and could increase *** this article,we describe a method based on binary linear programming for sensor network design balancing efficiency with *** application of the developed framework is demonstrated for the case of interior building surveillance utilizing infrared sensors in both twoand three-dimensional *** method provides optimal sensor placement,taking into account critical functionality and a desired level of resilience and considering sensor type and *** problem formulation,resilience requirements,and application of the optimization algorithm are described in *** of sensor locations with and without resilience requirements shows that resilient configuration requires redundancy in number of sensors and their intelligent *** tasks are successfully solved by the described method,which can be applied to strengthen the resilience of sensor networks by *** proposed methodology is suitable for large-scale optimization problems with many sensors and extensive coverage areas.

关键词： Binary linear programming Optimal sensor placement Redundant networks Resilience and efciency Resilient sensor networks

Effects of longitudinal magnetic field on primary dendrite spacing and segregation of directionally solidified single crystal superalloy

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Progress in Natural Science:Materials International 2024年第1期34卷 26-36页

作者： Congjiang Zhang Yilin Zhou Chen Shen Weili Ren Xiaotan Yuan Biao Ding Haibiao Lu Zuosheng Lei Yunbo Zhong Ang Zhang State Key Laboratory of Advanced Special Steel College of Materials Science and Engineering Shanghai University National engineering research center for Magnesium Alloys Natural Key Laboratory of Advanced Casting Technologies College of Materials Science and EngineeringChongqing University

The primary dendrite spacing(PDS) and segregation of directionally solidified single crystal(SC) superalloy under the longitudinal magnetic field(LMF) were investigated based on the analysis of the whole cross-sectional microstructure at different solidification distances. The results show that the PDS under the LMF remains basically unchanged at different solidification distances, and it is greater than that under no LMF. With the increase of magnetic field intensity, the PDS increases and the macrosegregation decreases. The increasing PDS and reducing segregation under the LMF can be attributed to the increase of solute boundary layer, which expands the non-equilibrium freezing temperature range and brings the effective partition coefficient closer to 1. The increase of the solute enrichment layer thickness could be caused by the downward secondary circulation generated by the thermoelectric magnetic convection(TEMC) near the interface, which drives the migration of solutes towards the interdendritic region. This work not only clarifies the mechanism of LMF controlling PDS and reducing segregation by TEMC, but also provides theoretical guidance for producing high-quality SC superalloys using magnetic fields.

关键词： Primary dendrite spacing Segregation Single crystal superalloy Directional solidification Magnetic field Thermoelectric magnetic convection

The Capture and Catalytic Conversion of CO_(2) by Dendritic Mesoporous Silica-Based Nanoparticles

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Energy & Environmental Materials 2024年第2期7卷 126-151页

作者： Yabin Wang Liangzhu Huang Songwei Li Chuntai Liu Hua He College of Chemistry and Chemical engineering Yan'an UniversityYan'an 716000China Institute for Triazine Compounds&Hierarchical Porous Materials Yan'an 716000China National engineering research center for Advanced Polymer Processing Technology Key Laboratory of Materials Processing and Mold(Ministry of Education)Zhengzhou UniversityZhengzhou 450002China

Dendritic mesoporous silica nanoparticles own three-dimensional center-radial channels and hierarchical pores,which endows themselves with super-high specific surface area,extremely large pore volumes,especially accessible internal spaces,and so *** guest species(such as organic groups or metal nanoparticles)could be readily decorated onto the interfaces of the channels and pores,realizing the functionalization of dendritic mesoporous silica nanoparticles for targeted *** adsorbents and catalysts,dendritic mesoporous silica nanoparticles-based materials have experienced nonignorable development in CO_(2)capture and catalytic *** comprehensive review provides a critical survey on this pregnant subject,summarizing the designed construction of novel dendritic mesoporous silica nanoparticles-based materials,the involved chemical reactions(such as CO_(2)methanation,dry reforming of CH_(4)),the value-added chemicals from CO_(2)(such as cyclic carbonates,2-oxazolidinones,quinazoline-2,4(1H,3H)-diones),and so *** adsorptive and catalytic performances have been compared with traditional silica mesoporous materials(such as SBA-15 or MCM-41),and the corresponding reaction mechanisms have been thoroughly *** is sincerely expected that the in-depth discussion could give materials scientists certain inspiration to design brand-new dendritic mesoporous silica nanoparticles-based materials with superior capabilities towards CO_(2)capture,utilization,and storage.

关键词： catalytic conversion CO_(2)adsorption CO_(2)capture dendritic mesoporous silica nanoparticles

Self-dispersed molybdenum disulfide quantum dot/graphene crumpled ball as efficient high temperature lubricant additive

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Friction 2024年第8期12卷 1771-1784页

作者： Guiru DU Yujuan ZHANG Shuguang FAN Ningning SONG Shengmao ZHANG Pingyu ZHANG engineering research center for Nanomaterials Henan UniversityKaifeng 475004China

Inorganic nanoparticles have been proved as powerful lubricant additives at elevated ***,the tribological properties are inevitably impaired due to poor dispersion and insufficient high temperature resistance of organic matter modified ***,we prepare a self-dispersed molybdenum disulfide quantum dot/graphene crumpled ball(MGCB)comprising molybdenum disulfide quantum dot uniformly interspersed on the wrinkled graphene *** crumpled ball composite possesses excellent dispersity in polyalkylene glycol base oil without depending on surface *** with the conventional phosphate esters lubricant,our results indicate MGCB could vastly improve the lubrication performance of polyalkylene glycol with an extremely low concentration(0.05 wt%)at elevated temperature(150°C),showing a friction reduction of 47%and a wear reduction of 30%compared with the conventional phosphate esters lubricant(tricresyl phosphate,TCP).This is because crumpled ball potentiates synergistic lubrication effect within the boundary ***,we envision our designed self-dispersed MGCB has significant potential in tribological application at elevated temperature.

关键词： self-dispersed crumpled ball graphene molybdenum disulfide quantum dot high temperature tribological properties

Process metallurgy and data-driven prediction and feedback of blast furnace heat indicators

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1228-1240页

作者： Quan Shi Jue Tang Mansheng Chu School of Metallurgy Northeastern UniversityShenyang 110819China Institute for Frontier technologies of Low-carbon Steelmaking Northeastern UniversityShenyang 110819China engineering research center of Frontier technologies for Low-carbon Steelmaking(Ministry of Education) Shenyang 110819China

The prediction and control of furnace heat indicators are of great importance for improving the heat levels and conditions of the complex and difficult-to-operate hour-class delay blast furnace(BF)*** this work,a prediction and feedback model of furnace heat indicators based on the fusion of data-driven and BF ironmaking processes was *** data on raw and fuel materials,process op-eration,smelting state,and slag and iron discharge during the whole BF process comprised 171 variables with 9223 groups of data and were comprehensively analyzed.A novel method for the delay analysis of furnace heat indicators was *** extracted delay variables were found to play an important role in *** method that combined the genetic algorithm and stacking efficiently im-proved performance compared with the traditional machine learning algorithm in improving the hit ratio of the furnace heat prediction *** hit ratio for predicting the temperature of hot metal in the error range of±10℃ was 92.4%,and that for the chemical heat of hot metal in the error range of±0.1wt%was 93.3%.On the basis of the furnace heat prediction model and expert experience,a feedback model of furnace heat operation was established to obtain quantitative operation suggestions for stabilizing BF heat *** sugges-tions were highly accepted by BF ***,the comprehensive and dynamic model proposed in this work was successfully ap-plied in a practical BF *** improved the BF temperature level remarkably,increasing the furnace temperature stability rate from 54.9%to 84.9%.This improvement achieved considerable economic benefits.

关键词： blast furnace furnace heat genetic algorithm stacking prediction and feedback

Synthesis of boron nitride nanorod and its performance as a metalfree catalyst for oxidative desulfurization of diesel fuel

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Chinese Journal of Chemical engineering 2024年第4期68卷 120-132页

作者： Tanaz Ghanadi Gholamreza Moradi Alimorad Rashidi Catalyst research center Faculty of Chemical and Petroleum EngineeringRazi UniversityKermanshahIran Nanotechnology research center Research Institute of Petroleum Industry(RIPI)TehranIran

In order to reduce the sulfur compounds in diesel fuel,boron nitride(BN)has been used as a novel metal-free catalyst in the present *** nanocatalyst was synthesized via template-free approach followed by heating treatment at 900℃ in nitrogen atmosphere that the characteristics of the sample were identified by the X-ray diffraction,Fourier-transform infrared spectroscopy,Raman spectroscopy,field emission scanning electron microscopy,transmission electron microscopy,atomic force microscopy,and N2 adsorption-desorption *** results of structural and morphological analysis represented that BN has been successfully *** efficacy of the main operating parameters on the process was studied by using response surface methodology based on the Box-Behnken design *** prepared catalyst showed high efficiency in oxidative desulfurization of diesel fuel with initial sulfur content of 8040 mg·kg^(-1)*** statistical analysis,a significant quadratic model was obtained to predict the sulfur removal as a function of efficient *** maximum efficiency of 72.4%was achieved under optimized conditions at oxidant/sulfur molar ratio of 10.2,temperature of 71℃,reaction time of 113 min,and catalyst dosage of 0.36 ***,the reusability of the BN was studied,and the result showed little reduction in activity of the catalyst after 10 times ***,a plausible mechanism was proposed for oxidation of sulfur compounds on the surface of the *** present study shows that BN materials can be selected as promising metal-free catalysts for desulfurization process.

关键词： Desulfurization Boron nitride(BN)nanostructure Experimental design BoxeBehnken

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

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Chinese Journal of Chemical engineering 2024年第3期67卷 282-297页

作者： Siang Chen Wenling Wu Zhaoyang Niu Deqi Kong Wenbin Li Zhongli Tang Donghui Zhang The research center of Chemical engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

Flue gas and coal bed methane are two important sources of greenhouse *** swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is *** this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 *** experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric *** the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular ***,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) *** study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

关键词： Activated carbon Carbon molecular sieve Adsorbent evaluation Adsorption equilibrium and kinetics Heat of adsorption Selectivity