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Effect of ferrotitanium slag on microstructure and properties of Al2O3-SiC-C castables for iron runner

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JOURNAL OF IRON AND STEEL resEARCH INTERNATIONAL 2024年第9期31卷 2122-2132页

作者： Long, Tu Gu, Hua-zhi Zhang, Mei-jie Huang, Ao Fu, Lv-ping Chen, Ding Qiu, Wen-dong Ju, Mao-qi Wuhan Univ sci & technol State Key Lab Refractories & Met Wuhan 430081 Hubei Peoples R China Baowu Equipment Intelligent technol co ltd Shanghai 200941 Peoples R China Wuhan res inst Met construct co ltd MCC Grp Wuhan 430081 Hubei Peoples R China

Ferrotitanium slag (FS) is a waste slag produced during the smelting of ferrotitanium alloys by thermite reduction. Its alumina content is high and can be used as alumina raw material. Iron runner castables containing different amounts of FS were prepared and characterized. The results show that the introduction of FS is beneficial to the sintering of the castables sample. When the FS concentration is 11.2 wt.%, the aggregate and matrix of the castables sample have a good combination, and the mechanical strength of the Al2O3-SiC-C castable reaches a maximum at room temperature. However, excessive introduction of FS generates a large amount of anorthite phase, which reduces the mechanical strength of the Al2O3-SiC-C castable at room temperature. In addition, the high-melting phase CaTiO3 is formed in FS, which has good mechanical properties. Meanwhile, the cracks of FS are reduced, and the combination between phases is closer, thus significantly improving the hot modulus of rupture of the castable. When the FS concentration is not above 33.6 wt.%, the castables show good slag resistance. The TiO2 in FS is transformed into TiC by carbothermal reaction, which is enriched at the boundary and prevents further reaction of the slag.

关键词： Ferrotitanium slag Al2O3-SiC-C castable Hot modulus of rupture Slag resistance ALUMINOTHERMIC REDUCTION PARTIAL SUBSTITUTION GLASS-CERAMICS coRROSION MECHANISM

Hollow engineering of sandwich NC@co/NC@MnO 2 composites toward strong wideband electromagnetic wave attenuation

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JOURNAL OF MATERIALS sciENCE & technolOGY 2024年第000期175卷 194-203页

作者： Wei, Chenhao Shi, Lingzi Li, Maoqing He, Mukun Li, Mengjie Jing, Xinrui Liu, Panbo Gu, Junwei Northwestern Polytech Univ Sch Chem & Chem Engn Shaanxi Key Lab Macromol Sci & Technol Xian 710072 Peoples R China Shaanxi coal Chem Ind technol res inst co ltd Xian 710123 Peoples R China

Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption, but still remain the formidable challenges in decreasing filler loadings. Herein, sandwich NC@co/NC@MnO2 composites with hollow cavity, multiple hetero-interfaces, and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrother-mal reaction. In the sandwich composites, middle magnetic components (co/NC) are wrapped by inner N-doped carbon (NC) matrix and outer hierarchical MnO2 nanosheets. Importantly, hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorp-tion bandwidth without sacrificing the absorption intensity. The maximum reflection loss of sandwich NC@co/NC@MnO2 composites reaches-44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm. These results provide us a new insight into preparing efficient electromag-netic wave absorbers by interface engineering and hollow construction.(c) 2023 Published by Elsevier ltd on behalf of The editorial office of Journal of Materials science & technology.

关键词： Interface engineering Sandwich structure Hetero -interfaces Interfacial polarization Electromagnetic wave absorption MICROWAVE MICROSPHEres coNSTRUCTION LIGHTWEIGHT FRAMEWORK

Heat transfer and flow structure in centrally-confined 2-D Rayleigh-Bénard convection

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JOURNAL OF HYDRODYNAMICS 2024年第4期36卷 772-780页

作者： Sun, cong Wu, Jian-zhao Meng, Xiao-hui Liu, Cai-xi Xu, Wei Dong, Yu-hong Zhou, Quan Shanghai Univ Shanghai Key Lab Mech Energy Engn Shanghai Inst Appl Math & Mech Sch Mech & Engn Sci Shanghai 200072 Peoples R China sci & technol res inst co ltd China Elect Equipment Grp Shanghai 200040 Peoples R China

Through direct numerical simulations, we investigated the flow structure and heat transfer of the centrally confined 2-D Rayleigh-B & eacute;nard (RB) convection over the Rayleigh number range 9 x 105 convection rolls in the central vertical channel increases from zero to three. When there is no rolls in the vertical channel, the convective flow in central region is significantly influenced by the boundary layer, whereas when the convection rolls is generated in the vertical channel, the convective flows in central regions is free from the boundary layer limitation, and by defining the characteristic length, one obtains the heat transfer scaling law relation in vertical channel, i.e., Nuvc similar to Ravc0.476 +/- 0.005, which could be the evidence of "ultimate regime".

关键词： Rayleigh-B & eacute nard (RB) turbulence heat transport vertical channel ultimate regime

Enhanced mechanical properties of giant magnetostrictive Tb-Dy-Fe alloy via constructing semi-coherent interface between matrix phase and ductile grain boundary phase

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JOURNAL OF MATERIALS sciENCE & technolOGY 2024年第000期175卷 185-193页

作者： Li, Jiheng Zhou, Zhiguang Han, Zhaopeng Yang, Zijing Bao, Xiaoqian Gao, Xuexu Univ sci & technol Beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Beijing res inst Mech & Elect Techno co ltd CSM Beijing 100083 Peoples R China

Giant magnetostrictive Tb-Dy-Fe alloys in the form of thin sheets or fine wires are required in precision micro-actuators and sensors. However, Tb-Dy-Fe alloys are too brittle to undergo machining and application. In the present work, we investigated the effects of diffusing the Dy 36 Cu 64 alloy into the grain boundary phases of the -oriented Tb0.30Dy0.70Fe1.95 alloy to modify the microstructural, mechanical, and magnetostrictive properties. Microstructural analysis revealed the introduction of Cu into the grain boundary phase through the diffusion treatment, transforming the brittle rare earth (RE)-rich grain boundary phase into a ductile (Tb,Dy)Cu grain boundary phase and changing the non-coherent interface to a semi-coherent one between the (Tb,Dy)Fe(2 )matrix phase and the grain boundary phase without affecting the microstructure of the matrix phase. The as-diffused Tb0.30Dy0.70Fe1.95 alloy exhibited significantly improved mechanical properties, with its tensile strength, bending strength, and fracture toughness at room temperature increasing to 44.6 MPa, 106.8 MPa, and 2.36 MPa m(1/2), respectively, which were 2, 2.4, and 1.5 times those of the non-diffused sample. This was attributed to the formation of ductile (Tb,Dy)Cu grain boundary phase and semi-coherent interfaces. Furthermore, the magnetostrictive strain of the as-diffused Tb0.30Dy0.70Fe1.95 alloy reached 1448 ppm, suggesting that there was minimal impact on the magnetostrictive properties, due to the small influence of grain boundary diffusion on the matrix phase.(c) 2023 Published by Elsevier ltd on behalf of The editorial office of Journal of Materials science & technology.

关键词： Tb-Dy-Fe alloys Magnetostriction Mechanical performance Grain boundary diffusion Semi-coherent interface TBDYFE STRENGTH NB co CU

Microstructure and microtexture evolution characteristics of a powder metallurgy Ni-based superalloy during static recrystallization

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JOURNAL OF IRON AND STEEL resEARCH INTERNATIONAL 2024年第9期31卷 2308-2325页

作者： Li, Zhi-qiang Wang, De-cheng Zhai, Yue-wen Jiang, Chao Zhou, Le-yu Zhou, Zhi-guang Wang, Hui-zhen Zhang, Zi-bo Yan, Lin Wang, Li-ping Yu, Guang Tsinghua Univ Dept Mech Engn Beijing 100084 Peoples R China Beijing res inst Mech & Elect technol co ltd CAM Beijing 100083 Peoples R China China Acad Machinery sci & technol Grp Beijing 100044 Peoples R China Beijing Univ technol Inst Adv Mfg & Intelligent Technol Beijing 100124 Peoples R China

Static recrystallization (SRX) characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080-1170 degrees C under strain rates of 0.01-0.1 s(-1), strains of 0.1, 0.22, or 0.5, and holding time of 0-300 s. The impacts of temperature, strain rate, holding time, and strain on the SRXed grain size, volume fraction, and microtexture were explored by electron backscatter diffraction technique. It was found that temperature played a key role in these processes. As SRX progressed, the fiber parallel to the axis compression direction gradually weakened and was replaced by the fiber because was the preferred recrystallization orientation and grain growth direction for the Ni-based superalloy. Moreover, high temperatures and low strain rates promoted the formation of the fiber. Three nucleation mechanisms during SRX process were found: grain boundary bulging, primary twin assistance, and subgrain coalescence. Grain boundary bulging occurred under all process conditions; however, at low temperatures and high strain rates, the latter two mechanisms could provide additional nucleation modes. In addition, SRX size and volume fraction models were established.

关键词： Powder metallurgy Ni-based superalloy Static recrystallization Microtexture evolution Recrystallization mechanism Prediction model NICKEL-BASED SUPERALLOY DYNAMIC RECRYSTALLIZATION HOT DEFORMATION DISSOLUTION BEHAVIOR GRAIN-GROWTH MECHANISMS ALUMINUM TEXTURE STEEL TWINS

Water vapor effects on the oxidation resistance of modified potassium silicate coating at high temperature

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JOURNAL OF MATERIALS sciENCE & technolOGY 2024年第000期176卷 25-35页

作者： Du, Yao Chen, Zheng Lu, Yiliang Wang, Cheng Yang, Lanlan Zhu, Shenglong Wang, Fuhui Univ sci & technol China Sch Mat Sci & Engn Shenyang 110016 Peoples R China Chinese Acad sci Shi Changxu Innovat Ctr Adv Mat Inst Met Res Shenyang 110016 Peoples R China State Grid Smart Grid res inst co ltd State Key Lab Adv Power Transmiss Technol Beijing 102209 Peoples R China Jiangsu JITRI Rd Engn technol & Equipment res inst Xuzhou 220005 Peoples R China Shenyang Natl Lab Mat sci Shenyang 110016 Peoples R China Northeastern Univ Sch Mat Sci & Engn Shenyang 110819 Peoples R China Jiangsu Univ sci & technol Sch Mat Sci & Engn Zhenjiang 212003 Peoples R China

An inorganic potassium silicate coating with pigments of alumina, aluminum phosphate, NiCrAlY and copper chromite black was prepared on CB2 stainless steel. Oxidation behavior in either ambient air or O2 + H2O mixture at 630 degrees C for 20 0 0 h was comparatively studied, and the coating exhibited excellent resistance under both test conditions. The water vapor considerably accelerated the oxidation of the un-coated CB2 steel, as the hydroxide, the main constituent of the coating, had a negligible evaporation rate at test temperature, while it had a limited effect on the coated sample. Meanwhile, the existence of coating may prolong or eliminate the incubation period in the O2 + H2O mixture at 630 degrees C. After oxidation, the coating matrix is in an amorphous state and fillers as alumina and copper chromite black are stable in the coating. Leucite (KAlSi2O6) formed by Al from NiCrAlY and potassium silicate in the coatings was detected after tests either in O2 or O2 + H2O mixture. (c) 2023 Published by Elsevier ltd on behalf of The editorial office of Journal of Materials science & technology.

关键词： CB2 stainless steel Inorganic silicate coating TEM High-temperature corrosion Oxidation ENHANCED OXIDATION BEHAVIOR PROTECTION VOLATILITY ALLOYS METAL

Theoretical and numerical research on effect of tension mechanisms in strip flatness electromagnetic control rolling mills

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JOURNAL OF IRON AND STEEL resEARCH INTERNATIONAL 2024年第9期31卷 2217-2235页

作者： Yang, Ting-song Yuan, Tie-heng Sun, Wen-quan He, An-rui Qu, Chun-tao Univ sci & technol Beijing Natl Engn Res Ctr Adv Rolling & Intelligent Mfg Beijing 100083 Peoples R China AECC Harbin Dongan Engine co ltd Inst Aeronaut Power Machinery Harbin 150000 Heilongjiang Peoples R China

To achieve stable rolling, the influence of a tension mechanism of a large diameter ratio roll system on the rolling process of a strip flatness electromagnetic control rolling mill is studied. Through the analysis of the rolling deformation zone, the deformation zone composition form of a large diameter ratio roll system and a calculation formula of neutral angle under tension are proposed. To analyze the effect of front and post tensions on the rolling characteristic and the strip flatness control characteristic, a three-dimensional rolling finite element (FE) model of a large diameter ratio roll system with the function of roll profile electromagnetic control is established by FE software and verified by a strip flatness electromagnetic control rolling mill. Based on the model, the strip thickness characteristic, metal transverse flow, strip flatness state, and adjustment range of the loaded roll gap are analyzed for different front and post tensions setting values. The results show that changing the front or post tension setting values can improve the single-pass reduction rate of a large diameter ratio roll system and have little effect on the flatness control ability of the strip flatness electromagnetic control rolling mill.

关键词： Strip flatness electromagnetic control rolling mill Tension mechanism Roll profile electromagnetic control technology Rolling characteristic Strip flatness control characteristic

Poloidal magnetic field reconstruction by laser-driven ion-beam trace probe in spherical tokamak

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PLASMA sciENCE & technolOGY 2024年第11期26卷 115102-115102页

作者： Zhang, Zuyu Xu, Tianchao Xiao, Chijie Huang, Xianli He, Renchuan Yuan, Ruixin Yang, Xiaoyi Peking Univ Sch Phys State Key Lab Nucl Phys & Technol Beijing 100871 Peoples R China ENN sci & technol Dev co ltd Langfang 065001 Peoples R China Harbin inst technol Harbin 150001 Peoples R China

The poloidal magnetic field ( plays a critical role in plasma equilibrium, confinement and transport of magnetic confinement devices. Multiple diagnostic methods are needed to complement each other to obtain a more accurate profile. Recently, the laser-driven ion-beam trace probe (LITP) has been proposed as a promising tool for diagnosing and radial electric field ( ) profiles in tokamaks [Yang X Y et al 2014 Rev. sci. instrum. 85 11E429]. The spherical tokamak (ST) is a promising compact device with high plasma beta and naturally large elongation. However, when applying LITP to diagnosing in STs, the larger invalidates the linear reconstruction relationship for conventional tokamaks, necessitating the development of a nonlinear reconstruction principle tailored to STs. This novel approach employs an iterative reconstruction method based on Newton's method to solve the nonlinear equation. Subsequently, a simulation model to reconstruct the profile of STs is developed and the experimental setup of LITP is designed for EXL-50, a middle-sized ST. Simulation results of the reconstruction show that the relative errors of reconstruction are mostly below 5%. Moreover, even with 5 mm measurement error on beam traces or 1 cm flux surface shape error, the average relative error of reconstruction remains below 15%, initially demonstrating the robustness of LITP in diagnosing profiles in STs.

关键词： laser-driven ion-beam trace probe poloidal magnetic field diagnostic iterative reconstruction EQUILIBRIUM REcoNSTRUCTION

Near zero thermal performance loss of Al-Si microcapsules with fibers network embedded Al2O3/AlN shell

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JOURNAL OF MATERIALS sciENCE & technolOGY 2024年第000期176卷 48-56页

作者： Zhang, J. X. Zhang, M. J. Li, H. F. Gu, H. Z. Chen, D. Zhang, C. H. Tian, Y. F. Wang, E. J. Mu, Q. N. Wuhan Univ sci & technol State Key Lab Refractories & Met Wuhan 430081 Peoples R China China Univ Geosci Fac Mat Sci & Chem Engn Res Ctr Nanogeomat Minist Educ Wuhan 430078 Peoples R China Henan Shenma Carbon Reduct technol co ltd Pingdingshan 467000 Peoples R China

Al-Si alloy, a high temperature phase change material, has great potential in thermal management due to its advantages of high heat storage density and thermal conductivity. Microencapsulation of Al-Si alloy is one of the effective techniques to solve high temperature leakage and corrosion. In this paper, com-mercial Al-10Si alloy micro powders were encapsulated with flexible ceramic shells whose total thickness is below 1 mu m by hydrothermal treatment and heat treatment in N 2 atmosphere. The compositions and microstructures were characterized by XRD, SEM and TEM. The shell was composed of AlN fibers net-work structure embedded with alpha-Al2O3/AlN which prevented the alloy from leaking and oxidizing, as well as had excellent thermal stability. The latent heat of microcapsules was 351.8 J g -1 for absorption and 372.7 J g -1 for exothermic. The microcapsules showed near zero thermal performance loss with latent heat storage (LHS)/ release (LHR) was 353.2/ 403.7 J g -1 after 30 0 0 cycles. compared with the published Al-Si alloy microcapsules, both high heat storage density and super thermal cycle stability were achieved, showing promising development prospects in high temperature thermal management. (c) 2023 Published by Elsevier ltd on behalf of The editorial office of Journal of Materials science & technology.

关键词： Al -Si alloy Microcapsules Ceramic shell AlN fiber network Thermal performance PHASE-CHANGE MATERIALS GRAIN-REFINEMENT ENERGY-STORAGE WHISKERS SILIcoN ALLOY GROWTH DURABILITY CAPACITY ALUMINUM