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Controlling segregation and hardenability of gear steel based on as-cast structure

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Journal of Iron and Steel Research International 2025年第1期32卷 144-158页

作者： Hai-jie Wang Ze Zhang Peng Lan gang Chen Pu Wang Chuan-hui jiang jia-quan Zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Weifang Iron and Steel Group Co. Ltd.Weifang 261000ShandongChina

Hardenability significantly impacts the distortion of gear during heat treatment,correlated to the uniformity of solute distribution in steel *** experimental analysis was conducted on the macrostructure,solute distribution,dendrite structure,and rod hardenability of 20CrMnTiH gear steel in continuously cast blooms and hot roller *** evaluation approach by the standards for the hardenability of gear steel rods and the corresponding blooms was analyzed,and the inheritance mechanism from solidification segregation to hardenability fluctuation of gear steel was *** results indicate that semi-macroscopic spot segregation located in the equiaxed zone exhibits larger size,higher solute enrichment,and worse solute homogeneity,leading to significant solute fluctuations in the blooms and hardenability fluctuation in the *** increasing the liquid steel superheat from 35 to 40℃,reducing the mold electromagnetic stirring from 300 to 100 A,and implementing the soft reduction(SR)of 7 mm at the solidification end,the equiaxed ratio of the strand decreased from 26.42%to 6.69%.Consequently,the solute fluctuation range and standard deviation decrease significantly in the transverse section,while the maximum segregation ratio,average fluctuation range,and average standard deviation of solutes C,Cr,and Mn in the spot segregation decrease at the same *** the meanwhile,the equiaxed ratio of the rod decreased from 24.89%to 4.09%,and the structure of the hardenability detection zone was transformed from equiaxed crystals to columnar ***,the solute fluctuation range and standard deviation in the transverse section decreased,while the homogeneity in spot segregation was also *** hardness difference of A and B surfaces at J9 and J15 positions was smaller than 2 HRC,meeting the qualification standard for hardenability.

关键词： Gear steel Continuous casting Solute distribution Dendritic structure Hardenability

The Stereocomplex Crystallites Improve the Stability of Biodegradable Poly(L-lactic acid)/Poly(D-lactic acid)Melt-Blown Nonwovens

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Chinese Journal of Polymer Science 2025年第2期43卷 368-379页

作者： Jin-Shuo Yu Yue-Wei Huan Hong-Wei Pan Zhi-gang Liu Yan Zhao Zhi-Yong Tan Jun-jia Bian Hui-Li Yang Hui-Liang Zhang Key Laboratory of Polymer Ecomaterials Chinese Academy of SciencesChangchun Institute of Applied ChemistryChangchun130022China College of Material and Engineering School of Chemical EngineeringEngineering Research Center of Synthetic Resin and Special FiberMinistry of EducationChangchun University of TechnologyChangchun130012China Shandong Fufeng Fermentation Co. Ltd.Shandong276600China National Engineering Research Center of Corn Deep Processing Jilin COFCO Biochemistry Co.Ltd.Changchun130033China

Poly(lactic acid)(PLA)is a biodegradable and eco-friendly polymer that is increasingly being incorporated into various applications in contemporary ***,the limited stability of PLA-based products remains a significant challenge for their broader use in various *** this study,poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)melt-blown nonwovens were prepared by melt *** structure,thermal properties,thermal stability,biodegradability and crystalline morphology of the melt-blown nonwovens were *** and WAXD confirmed the formation of stereocomplex(SC)crystallites in the PLLA *** storage modulus(G′),loss modulus(G″),and complex viscosity(∣η^(*)∣)of the PLLA/PDLA blend increased with an increase in SC crystallite *** thermal degradation temperatures of PLLA/PDLA melt-blown nonwovens increased with the incorporation of SC crystallites,and the maximum rate of decomposition increased to 385.5℃,thus enhancing the thermal *** with neat PLLA melt-blown nonwovens,the hydrophobicity of PLLA/PDLA melt-blown nonwovens was improved,and WCA increased to 139.7°.The SC crystallites were more resistant to degradation by proteinase K compared to neat ***,the degradation rate of PLLA/PDLA melt-blown nonwovens remained at a high *** work provides an effective strategy to obtain high-performance PLLA melt-blown nonwovens.

关键词： PLLA PDLA Melt-blown nonwovens Stereocomplex crystallites Thermal stability Enzymatic degradation

Understanding the local structure and thermophysical behavior of Mg-La liquid alloys via machine learning potential

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 439-449页

作者： jia Zhao Taixi Feng Guimin Lu National Engineering Research Center for Integrated Utilization of Salt Lake Resource East China University of Science and TechnologyShanghai 200237China Joint International Laboratory for Potassium and Lithium Strategic Resources East China University of Science and TechnologyShanghai 200237China

The local structure and thermophysical behavior of Mg-La liquid alloys were in-depth understood using deep potential molecular dynamic(DPMD) simulation driven via machine learning to promote the development of Mg-La alloys. The robustness of the trained deep potential(DP) model was thoroughly evaluated through several aspects, including root-mean-square errors(RMSEs), energy and force data, and structural information comparison results;the results indicate the carefully trained DP model is reliable. The component and temperature dependence of the local structure in the Mg-La liquid alloy was analyzed. The effect of Mg content in the system on the first coordination shell of the atomic pairs is the same as that of temperature. The pre-peak demonstrated in the structure factor indicates the presence of a medium-range ordered structure in the Mg-La liquid alloy, which is particularly pronounced in the 80at% Mg system and disappears at elevated temperatures. The density, self-diffusion coefficient, and shear viscosity for the Mg-La liquid alloy were predicted via DPMD simulation, the evolution patterns with Mg content and temperature were subsequently discussed, and a database was established accordingly. Finally, the mixing enthalpy and elemental activity of the Mg-La liquid alloy at 1200 K were reliably evaluated,which provides new guidance for related studies.

关键词： magnesium-lanthanum liquid alloys local structure macroscopic properties thermodynamic behavior deep potential mo-lecular dynamic simulation

Understanding amorphous PrO_(x)-based N-doped carbon catalyst as an efficient electrocatalyst for oxygen reduction reaction

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Journal of Rare Earths 2025年第1期43卷 73-80,I0003页

作者： Xiao Man Ying Chang Shaohong Guo Meilin jia Jingchun jia Inner Mongolia Key Laboratory of Green Catalysis and Inner Mongolia Collaborative Innovation Center for Water Environment Safety College of Chemistry and Environmental ScienceInner Mongolia Normal UniversityHohhot010022China

The development of an e fficacious and easily prepared no nprecious metal electrocatalyst is crucial for the oxygen reduction reaction(ORR).This work used a dual template method to prepare the amorphous rare earth-based catalyst PrO_(x)-NC,and optimized the calcination temperature and *** PrO_(x)-NC-900 catalyst has high durability and activity and exhibits superior ORR performance in alkaline electrolytes with an onset potential(E_(0))of 0.96 V and a half-wave potential(E_(1/2))of 0.85 *** research results indicate that the ORR performance of rare earth oxide composite carbon catalysts can be improved by adjusting oxygen vacancies(Ov).In addition,high specific surface area,N rich defect *** oxygen vacancies,and the synergistic effect of oxygen vacancies and N-doped carbon interfacial layer play a significant part in the enhancement of *** performance of the zinc air battery assembled with PrO_(x)-NC-900 is significantly improved,and rare earth oxides and carbon frameworks originating from metal organic frameworks(MOFs)contribute to the oxygen electrocatalyst and electron transfer rate of the zinc air *** catalyst provides promising information for the development of rare earth metal oxide nanostructures as potential candidate materials for ORR in alkaline media.

关键词： Rare earths Metal-organic framework Oxygen reduction reaction Zn-air batteries

Molecular-based porous polymers with precise sites for photoreduction of carbon dioxide

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Chinese Chemical Letters 2025年第1期36卷 201-213页

作者： Wei-jia Wang Kaihong Chen College of Biological and Chemical Engineering Zhejiang University of Science and TechnologyHangzhou 310023China The Institute of Green Chemistry and Engineering School of Chemistry and Chemical EngineeringNanjing UniversitySuzhou 215163China

Photocatalytic CO_(2)reduction reaction(CO_(2)RR)is one of the promising strategies for sustainably producing solar *** precise identification of catalytic sites and the enhancement of photocatalytic CO_(2)conversion is imperative yet quite *** critical review summarizes recent advances in porous photo-responsive polymers,including covalent organic frameworks(COFs),covalent triazine frameworks(CTFs),and conjugated microporous polymers(CMPs),those can be rationally designed from the molecular level for visible-light-driven photocatalytic CO_(2)***,special emphasis is placed on how the well-defined active sites on these polymers can influence their properties and photocatalytic *** precise regulation and control of microenvironments and electronic properties of metal active centers are crucial for boosting catalytic efficiency and selectivity,as well as for the design of better photocatalysts for CO_(2)reduction.

关键词： Carbon dioxide reduction Photocatalysis Porous polymers Well-defined catalytic sites Molecular level

Effect of GaInP and GaAsP inserted into waveguide/barrier interface on carrier leakage in InAlGaAs quantum well 808-nm laser diode

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中国光学(中英文) 2025年第1期18卷 186-197页

作者： FU Meng-jie DONG Hai-liang jia Zhi-gang jia Wei LIANG jian XU Bing-she Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan 030024China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Institute of Atomic and Molecular Science Shaanxi University of Science&TechnologyXi’an 710021China

There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug *** this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of *** results show that the leakage current density reduces by 87.71%,compared to traditional *** nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room *** addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is *** novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.

关键词： 808-nm laser diode Ga_(0.55)In_(0.45)P and GaAs_(0.6)P_(0.4)insertion layers InAlGaAs quantum well carrier leakage

Anchoring 1T-MoS_(2)petals on N-doped reduced graphene oxide for exceptional electromagnetic wave absorption

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International Journal of Minerals,Metallurgy and Materials 2025年第3期32卷 619-630页

作者： jia Zhao Haoran Lai Ming Li College of Chemistry and Materials Engineering Bohai UniversityJinzhou 121013China Yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou 313001China College of Chemistry and Chemical Engineering Jishou UniversityJishou 416000China

The effective construction of electromagnetic(EM)wave absorption materials with thin matching thickness,broad bandwidth,and remarkable absorption is a great solution to EM pollution,which is a hot topic in current environmental *** this study,N-doped reduced graphene oxide(N-rGO)was first prepared using a facile hydrothermal ***,high-purity 1T-MoS_(2)petals were homogeneously anchored to the wrinkled surface of N-rGO to fabricate 1T-MoS_(2)@N-rGO *** numerous electric di-poles and profuse heterointerfaces in 1T-MoS_(2)@N-rGO would induced the multiple reflection and scattering of EM waves in a distinct-ive multidimensional structure formed by two-dimensional N-rGO and 1T-MoS_(2)microspheres with plentiful thin nanosheets,remarkable conduction loss derived from the migration of massive electrons in a well-constructed conductive network formed by 1T-MoS_(2)@N-rGO,and abundant polarization loss(including dipolar polarization loss and interfacial polarization loss).All of these gave the 1T-MoS_(2)@N-rGO nanocomposites superior EM wave absorption *** effective absorption bandwidth of 1T-MoS_(2)@N-rGO reached 6.48 GHz with a relatively thin matching thickness of 1.84 mm,and a minimum reflection loss of-52.24 dB was achieved at 3.84 ***,the radar scattering cross-section reduction value of 1T-MoS_(2)@N-rGO was up to 35.42 dB·m^(2) at 0°,which further verified the huge potential of our fabricated 1T-MoS_(2)@N-rGO nanocomposites in practical applications.

关键词： 1T-MoS_(2)@N-rGO nanocomposites conduction loss polarization loss ultrathin matching thickness electromagnetic wave absorption

Ultra-stable Co-based metallic glassy microwires for highly sensitive giant-magnetoimpedance sensors

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Science China(Physics,Mechanics & Astronomy) 2025年第04期Mechanics & Astronomy) .卷 156-164页

作者： Yuyang Qian Chaoqun Pei Haibo Ke Xintao Wei Dengke Wang Yandong jia Baoan Sun gang Wang Weihua Wang Institute of Materials School of Materials Science and Engineering Shanghai University Songshan Lake Materials Laboratory Institute of Physics Chinese Academy of Sciences

The development and deployment of giant magnetoimpedance(GMI) sensors have been significantly hampered by their limited sensitivity to weak magnetic fields and pronounced thermal drift phenomena, both of which are intricately linked to the microstructural properties of the sensor core material, typically composed of metallic glass microwires(MGMWs). Herein, we successfully fabricated an ultra-stable Co-based MGMW with a high GMI effect through a novel multi-step stress-Joule coupled annealing(MS-JCA) technique. The Co-based MGMW showcases a significantly improved GMI effect with an unprecedented impedance change rate of 939%, coupled with an enhanced magnetic field sensitivity of 734%/Oe. In addition,the MS-JCA process ensures the GMI sensor retains exceptional stability during thermal drift measurements over a span of20 h, characterized by a minimal signal fluctuation ratio of merely 0.59%. Notably, the ultra-stability of the GMI sensor arises from the ultra-stable energy state of the MGMWs following MS-JCA. Our findings offer a compelling strategy for significantly enhancing both the performance and stability of GMI sensors, thereby establishing a solid technical foundation for their broader application in weak magnetic detection.

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Global adaptive output feedback control of nonlinear time-delay systems with measurement uncertainty

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Control Theory and Technology 2025年第1期23卷 145-152页

作者： Weiguo Cai Xianglei jia Xinxu Ju School of Automation Hangzhou Dianzi UniversityHangzhou310018ZhejiangChina

In this paper,a pair of dynamic high-gain observer and output feedback controller is proposed for nonlinear systems with multiple unknown time *** constructing Lyapunov-Krasovskii functionals,it shows that global state asymptotic regulation can be ensured by introducing a single dynamic gain;furthermore,global asymptotic stabilization can be achieved by choosing a sufficiently large static scaling gain when the upper bounds of all system parameters are ***,the output coefficient is allowed to be non-differentiable with unknown upper *** paper proposes a generalized Lyapunov matrix inequality based dynamic-gain scaling method,which significantly simplifies the design computational complexity by comparing with the classic backstepping method.

关键词： Output feedback Measurement uncertainty Nonlinear adaptive control Time delays