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Forming process chain for manufacturing complex conical-section profiled rings:On a co-design method

Chinese Journal of Aeronautics 2024年第6期37卷 485-503页

作者： Lei LIANG Chaojiang ZOU Lianggang GUO State Key Laboratory of Solidification processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Guizhou Aviation Technology Development Co.Ltd Guiyang 550081China

The final quality of complex conical-section rings depends on co-design of multiple processes in forming process *** this study,for a complex aeroengine casing ring with a large slope and a flange on its end,a co-design method of the forming process chain is put forward towards the objective of precision forming,which not only proposes a standard process route composed of multiple processes of upsetting,punching,rectangular ring rolling,loose tooling forging and profiled ring rolling,but also presents co-design methods of dies and blanks for all the *** profiled ring rolling,a design method of preformed blank that makes the blank and the target conical-section ring have the same axial volume distribution is *** the method,the axial metal redistribution during the process can be alleviated greatly thus improving the forming stability and precision of the *** on the geometric features of designed preformed blank,design methods of blanks and dies for loose tolling forging,rectangular ring rolling,punching and upsetting are proposed *** view of the key roles of loose tooling forging(manufacturing the preformed blank)and profiled ring rolling on the final quality of the conical ring parts,inherited FE simulations for these two processes are performed to verify the proposed design methods and determine appropriate design *** is demonstrated that the proposed design method has significant advantages in improving forming ***,a suggestive value 1.5 of the rolling ratio for profiled ring rolling(a key design parameter)is given based on comprehensive consideration of multiple indicators such as ring roundness,deformation uniformity and forming *** corresponding industrial experiments performed illustrate that a high forming precision of the conical-section aeroengine casing ring is achieved.

关键词： Complex conical-section ring Co-design of forming process chain Profiled ringrolling Preformed blank Loose tooling forging

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Carbon nanofibers embedded with Fe-Co alloy nanoparticles via electrospinning as lightweight high-performance electromagnetic wave absorbers

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Rare Metals 2024年第6期43卷 2769-2783页

作者： Wen-Jun Cai Jian-Guo Jiang Zi-Dong Zhang Zi-Xuan Liu Lu-JieZhang Zhen-Kun Long Ke Bi Key Laboratory for Liquid-Solid Structural Evolution and processing of materials(Ministry of Education) Shandong UniversityJinan 250061China School of materials Science and Engineering Shandong UniversityJinan 250061China Energy Institute Qilu University of Technology(Shandong Academy of Sciences)Jinan 250014China State Key Laboratory of Information Photonics and Optical Communications School of ScienceBeijing University of Posts and TelecommunicationsBeijing 100876China

As a lot of electromagnetic pollution and interference issues have emerged,to overcome electromagnetic interference,prevent electromagnetic hazards,and develop new high-performance electromagnetic wave(EMW)absorbers have become a significant task in the field of materials *** this paper,a three-dimensional(3D)carbon nanofibers network with core-shell structure,embedded with varied molar ratios of iron and cobalt(4:0,3:1,2:2,1:3,0:4),was effectively synthesized(Fe/Co@C-CNFs)via *** phase,microstructure,magnetic and EMW absorption properties were *** is discovered that Fe/Co@C-CNFs doped with iron:cobalt=1:1 have excellent EMW absorption *** the matching thickness is 1.08 mm,the minimum reflection loss(RL)value is-18.66 dB,while the maximum effective absorption bandwidth(EAB)reaches 4.2 GHz(13.9-18 GHz)at a thickness of 1.22 *** is owing to the absorbers'superior impedance matching and multiple reflections as well as the conductivity,dielectric,and magnetic losses of carbon nanofibers embedded with Fe-Co alloy *** addition,the radar cross section(RCS)of the absorbers has been calculated by CST Studio Suite,showing that the absorbing coating can effectively reduce the RCS at various angles,especially for Fe/Co@C-CNFs doped with iron:cobalt=1:*** findings not only provide new insights for the preparation of light-weight and high-performance electromagnetic wave absorbers,but also contribute to energy storage and conversion.

关键词： Electromagnetic wave(EMW)absorbers Fe/Co@C-CNFs Core-shell structure EMW absorbing mechanism Radar cross section(RCS)

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Recent research progress in the mechanism and suppression of fusion welding-induced liquation cracking of nickel based superalloys

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International Journal of Minerals,Metallurgy and materials 2024年第5期31卷 1072-1088页

作者： Zongli Yi Jiguo Shan Yue Zhao Zhenlin Zhang Aiping Wu Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China College of Engineering China Agricultural UniversityBeijing 100091China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for Advanced materials processing Technology Ministry of EducationBeijing 100084China School of Material Science and Engineering Southwest Jiaotong UniversityChengdu 610031China

Nickel-based superalloys are extensively used in the crucial hot-section components of industrial gas turbines,aeronautics,and astronautics because of their excellent mechanical properties and corrosion resistance at high *** welding serves as an effective means for joining and repairing these alloys;however,fusion welding-induced liquation cracking has been a challenging *** paper comprehensively reviewed recent liquation cracking,discussing the formation mechanisms,cracking criteria,and *** recent investigations,regulating material composition,changing the preweld heat treatment of the base metal,optimizing the welding process parameters,and applying auxiliary control methods are effective strategies for mitigating *** promote the application of nickel-based superalloys,further research on the combination impact of multiple elements on cracking prevention and specific quantitative criteria for liquation cracking is necessary.

关键词： nickel-based superalloy fusion welding liquation cracking cracking mechanism cracking suppression

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processing and characterization of polymer precursor derived silicon oxycarbide ceramic foams and compacts

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Journal of Advanced Ceramics 2013年第4期2卷 318-324页

作者： Srinivasan NEDUNCHEZHIAN Ravindran SUJITH Ravi KUMAR materials processing section Department of Metallurgical and Materials EngineeringIndian Institute of Technology MadrasChennai 600036Tamil NaduIndia

This work focused on the fabrication of silicon oxycarbide ceramic(SiOC)foams as well as dense compacts using poly(hydridomethylsiloxane)(PHMS)as a polymer *** room-temperature cross-linking of PHMS was achieved by the addition of 1,4-diazabicyclo[2.2.2]octane(DABCO)with the release of hydrogen gas as a *** resulted in self-blowing of the polymer precursor at room temperature and thereby offered the possibility of producing SiOC foams without the need of any external blowing *** also reported the fabrication of crack-free silicon oxycarbide compacts by cold compaction and pyrolysis route using polyvinyl alcohol(PVA)as a processing ***-shaped pellets were pyrolysed at 1300℃in argon atmosphere with a ceramic yield of approximately 85%.Increased resistance to phase separation and crystallization up to 1400℃was attributed to the presence of large volume fraction of free carbon in the material which was confirmed by Raman spectroscopy.

关键词： silicon oxycarbide foams 1,4-diazabicyclo[2.2.2]octane(DABCO) self-blown polymer poly(hydridomethylsiloxane)(PHMS)

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Genetic Analysis of Structural Styles in the Makran Accretionary Wedge–Insight from Physical Simulations

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Journal of Ocean University of China 2024年第1期23卷 157-172页

作者： SHAO Longfei YU Fusheng GONG Jianming LIAO Jing YU Zhifeng TANG Liang CHEN Jiangong WANG Yuefeng NENG Yuan School of Earth Sciences China University of PetroleumBeijing 102249China State Key Laboratory of Petroleum Resources and processing China University of PetroleumBeijing 102249China Qingdao Institute of Marine Geology China Geological SurveyQingdao 266071China China University of Petroleum–Beijing at Karamay Karamay 834000China

The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the formation mechanism of shallow normal faults, remain unclear. Meanwhile, the factors affecting the continuity of plane faults must be comprehensively discussed. Clarifying the development characteristics and deformation mechanisms of the Makran accretionary wedge is crucial to effectively guide the exploration of gas hydrate deposits in the area. This study aims to interpret seismic data to identify typical structures in the Makran accretionary wedge, including deep imbricate thrust faults, shallow and small normal faults, wedge-shaped piggyback basins, mud diapirs with fuzzy and disorderly characteristics of reflection, décollements with a northward tilt of 1° – 2°, and large seamounts. Physical simulation-based experiments are performed to comprehensively analyze the results of the plane, section, and slices of the wedge. Results reveal that the distances between and shapes of thrust faults in the deep parts of the Makran accretionary wedge are controlled by the bottom décollement. The uplift of the thrust fault-related folds and the upwelling of the mud diapirs primarily contribute to the formation of small normal faults in the shallow part of the area. The mud diapirs originate from plastic material at the bottom, while those that have developed in the area near the trench are larger. Seamounts and mud diapirs break the continuity of fault plane distribution.

关键词： Makran accretionary wedge structural styles faults distribution physical simulation

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Micro-flow structure at regime transition from bubbling to turbulent fluidization in a fluidized bed

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Particuology 2024年第6期89卷 117-130页

作者： Chaoyu Yan Yue Yuan Xiaoyang Wei Jesse Zhu State Key Laboratory of Heavy Oil processing Beijing Key Laboratory of Process Fluid Filtration and SeparationCollege of Mechanical and Transportation EngineeringChina University of PetroleumBeijing 102249China China Beacons Institute The University of NottinghamNingbo315100China Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioN6A 5B9Canada

Gas-solid fluidized beds have found extensive utilization in frontline manufacturing,in particular as low-velocity *** fluidization status,the bubbling or turbulent flow regime and the transition in between,determine the system performance in practical *** the convoluted hydrodynamics are quantitively evaluated through numerous data-processing methodologies,none of them alone can reflect all the critical information to identify the transition from the bubbling to the turbulent ***,this study was to exploit a coupling data processing methodology,in the combination of standard deviation,power spectrum density,probability density function,wavelet transform,and wavelet multiresolution method,to jointly explain the micro-flow structure at the regime transition from bubbling to turbulent *** transient differential pressure fluctuation was measured for the evaluation in a fluidized bed(0.267 m i.d.×2.5 m height)with FCC catalysts(d_(p)=65μm,ρ_(p)=1780kg/m^(3))at different superficial gas velocities(0.02–1.4 m/s).The results show that the onset of turbulent fluidization starts earlier in the top section of the bed than in the bottom *** wavelet decomposition displays that the fluctuation of differential pressure mainly concentrates on the sub-signals with an intermediate frequency *** sub-signals could be synthesized into three types of scales(micro-scale,meso-scale,and macro-scale),representing the multi-scale hydrodynamics in the fluidized *** micro-scale signal has the characteristic information of bubbling fluidization,and the characteristic information of turbulent fluidization is mainly represented by the meso-scale *** work provides a systematic comprehension of fluidization status assessment and serves as an impetus for more coupling analysis in this sector.

关键词： Flow regime transition Bubbling fluidization Turbulent fluidization Micro-flow structure Differential pressure fluctuation

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Characterization of free carbon in the as-thermolyzed Si-B-C-N ceramic from a polyorganoborosilazane precursor

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Journal of Advanced Ceramics 2013年第4期2卷 325-332页

作者： Adhimoolam Bakthavachalam KOUSAALYA Ravi KUMARa Shanmugam PACKIRISAMY materials processing section Department of Metallurgical and Materials EngineeringIndian Institute of Technology MadrasChennai 600036Tamil NaduIndia Analytical Spectroscopy and Ceramics Group PCM EntityVikram Sarabhai Space CentreThiruvananthapuram 695022India

Polyorganoborosilazane((B[C_(2)H_(4)-Si(CH_(3))NH]_(3))n)was synthesized via monomer route from a single-source precursor and thermolyzed at 1300℃in argon *** as-thermolyzed Si-B-C-N ceramic was characterized using X-ray diffraction(XRD)and Raman *** crystallization behavior of silicon carbide in the as-thermolyzed amorphous Si-B-C-N matrix was understood by XRD studies,and the crystallite size calculated using Scherrer equation was found to increase from 2 nm to 8 nm with increase in dwelling ***,Raman spectroscopy was used to characterize the free carbon present in the as-thermolyzed *** peak positions,intensities and full width at half maximum(FWHM)of D and G bands in the Raman spectra were used to study and understand the structural disorder of the free *** G peak shift towards 1600 cm-1 indicated the decrease in cluster size of the free *** cluster diameter of the free carbon calculated using TK(Tuinstra and Koenl)equation was found to decrease from 6.2 nm to 5.4 nm with increase in dwelling time,indicating increase in structural disorder.

关键词： synthesis polyorganoborosilazane precursor-derived ceramic Si-B-C-N Raman spectroscopy free carbon

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Phase relationship of Dy-Fe-Mn system at 773 K

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Journal of Rare Earths 2014年第7期32卷 655-662页

作者：杜成梅马君姚路陈国坚杨通晗曾维敬何维 Key Laboratory of Nonferrous Metal materials and New processing Technology College of Materials Science and EngineeringMinistry of EducationGuangxi University

Rare-earth intermetallic compounds formed in many R-Fe-Mn（R=rare-earth element） systems exhibit excellent properties. In order to understand the existence and stability of the compounds in the system and further search for the potential application of R-Fe-Mn alloys in various aspects, it is necessary to investigate the phase relations of the Dy-Fe-Mn ternary system. A total of 96 samples of the Dy-Fe-Mn alloys were prepared by arc-melting and examined by metallographic analysis, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS） techniques. The phase relationship of the Dy-Fe-Mn system at 773 K was determined. It was found that the isothermal section was characterized by intermediate solid solutions based on the substitutions of Fe/Mn atoms and the large extensions of the binaries into the ternary domains. The solid solubilities of the third element in the binary compounds and the phase boundaries were also determined by XRD technique using the phase disappearing method combined with the lattice parameter method and SEM/EDS technique. Two pairs of corresponding binary compounds in the Dy-Fe and Dy-Mn systems（DyFe2 and DyMn2, Dy6Fe23 and Dy6Mn23） formed a continuous series of solid solution at 773 K, respectively.

关键词： Dy-Fe-Mn phase diagram crystal structure X-ray diffraction rare earths

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Phase equilibria in Nb-Y-Si ternary system at 873 K

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Journal of Rare Earths 2012年第9期30卷 934-940页

作者：姜文平湛永钟李春流柳帅周慧黠庄应烘 Laboratory of Nonferrous Metal materials and New processing Technology Ministry of EducationGuangxi University

The isothermal section of the Nb-Y-Si ternary system at 873 K was investigated over the whole concentration range mainly by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive analysis （EDX）. This isothermal section con- sisted of 10 single-phase regions, 17 two-phase regions, and 8 three-phase regions. The existence of the binary compounds, i.e., Y5Si3, Y5Si4, YSi, Y3Sis, YSi〉 NbsSi3 and NbSi2 at 873 K was confirmed. On the basis of XRD patterns, the structure types of Y3Si4, Y3Si5 and YSi2 were discussed. No ternary compound and no detectable solid solubility in the binary compounds were found.

关键词： Nb-Y-Si phase diagram isothermal section XRD rare earths

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Effect of combined electromagnetic fields on surface quality and structure of a HDC casting 5182 Al alloy ingot

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Acta Metallurgica Sinica(English Letters) 2012年第6期25卷 453-460页

作者： Qingfeng ZHU Zhihao ZHAO Yubo ZUO Xiangjie WANG Jianzhong CUI Key Laboratory of Electromagnetic processing of materials Ministry of Education Northeastern University Shenyang 110819 China

5182 Al alloy ingots with the diameters of 100 mm are produced by conventional and combined electromagnetic fields （CEMF） horizontal direction chill （HDC） cast- ing process. The effect of CEMF on the ingot surface quality and floating grains is investigated. The results show that the CEMF is effective in reducing the segregation layer in both top and bottom sub-surfaces. Big floating grains with coarse dendrite arms mainly distribute in the crescent-shaped area near the bottom in the conven- tional HDC casting ingot. With the application of the CEMF, they disappear in the whole cross section of the HDC casting ingot and the equiaxed grains are significantly refined.

关键词： Aluminum alloy Combined electromagnetic field Horizontaldirect chill casting Structure Surface quality

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