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Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

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Journal of Materials Science & Technology 2018年第1期34卷 192-197页

作者： l.h. Wu K. Nagatsuka K. Nakata Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka 567-0047 Japan

Oxygen-flee copper （Cu） was successfully joined to carbon-fiber-reinforced thermoplastic （CFRTP, polyamide 6 with 20wt% carbon fiber addition） by friction lap joining （FlJ） at joining speeds of 200-1600 mm/min with a constant rotation rate of 1500 rpm and a nominal plunge depth of 0.9 ram. It is the first time to report the joining of CFRTP to Cu by FlJ. As the joining speed increased, the tensile shear force （TSF） of joints increased first, and decreased thereafter. The maximum TSF could reach 2.3 kN （ 15 mm in width）. hydrogen bonding formed between the amide group of CFRTP and the thin Cu20 layer on the Cu surface, which mainly contributed to the joint bonding. The influence factors of the TSF of the joints at different joining speeds were discussed. The TSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased, the influence factors varied as follows： the joining area increased first and then decreased; the degra- dation of the plastic matrix and the number and the size of bubbles decreased. The maximum TSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.

关键词： Friction lap joining Metal Plastic Carbon-fiber reinforced thermoplastic Dissimilar materials joining

Influence of austenization temperature on the erosion behavior of austempered ductile irons

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Journal of University of Science and Technology Beijing 2008年第1期15卷 29-33页

作者： l.C. Chang l C. hsui l.h. Chen S.T. lui Department of Mechanical Engineering Technology and Science Institute of Northern Taiwan Taipei 112 China Talpei Department of Materials Science and Engineering Cheng-Kung University Talnan 800 China Taipei

The erosion behavior of austempered ductile irons austenized at different temperatures was studied. The results indicate that the erosion rate well correlates with the mechanical properties. At high impact angles, increasing ductility and mechanical energy density results in decreasing erosion rate, whereas increasing hardness reduces the erosion rate at low impact angles. 2008 University of Science and Technology Beijing. All rights reserved.

关键词： austempered ductile iron erosion mechanical properties austenization

PhYSICAl SIMUlATION OF CONTINUOUS ROll CASTING PROCESS

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Acta Metallurgica Sinica(English letters) 2005年第4期18卷 505-511页

作者： l.h. Zhan J. Zhong X.Q. li M.h. huang College of Electronical-Mechanical Engineering Central South University Changsha 410083China

A series of simulating experimental studies on the rheological behavior and its influential factors of aluminum alloy in continuous roll-casting process have been explored in this paper with a Gleeble-1500 Thermal-Mechanical Simulation Tester and a set of special clamp system. Relevant rheological rules in the process of coupling transient solidification and continuous deformation of roll-casting conditions are obtained. Experimental results indicate that four different characteristic stages exist in the whole rheological process, and relative constitutive models suitable for the given conditions of continuous roll casting process have been established through multivariable linear regression analysis of the experimental data.

关键词： continuous roll-casting rheological behavior physical simulation,constitutive relation

Effect of Mo Addition on Microstructural Characteristics in a Re-containing Single Crystal Superalloy

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Journal of Materials Science & Technology 2015年第2期31卷 143-147页

作者： X.G.liu l.Wang l.h.lou J.Zhang Superalloys Division Institute of Metal ResearchChinese Academy of Sciences Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

The effect of Mo addition on microstructural characteristics of a nickel-base single crystal superalloy containing 4 wt% Re was investigated. The γ/γ’ partitioning ratios determined by energy dispersive spectrometer attached to a transmission electron microscope showed that the addition of Mo enhanced the partitioning of Re,W and Cr in the g matrix while decreased the concentration of Ta in the matrix. Synchrotron radiation diffraction was adopted to measure the γ/γ’ lattice misfit at room temperature. The results indicated that Mo addition changed the γ/γ’ lattice misfit towards larger negative as well as increased the tetragonal distortion of the γ lattice. Additionally,Mo addition led to microstructural instability and altered the precipitation behavior of topologically close-packed phases during 1100 C exposure. Instead of precipitating directly from the matrix,the μ phase was observed to be converted from the α phase which precipitated preferentially as a metastable intermediate in the alloy with high Mo content.

关键词： Superalloy Molybdenum Microstructure Partitioning

healing Process of Casting Pores in a Ni-based Superalloy by hot Isostatic Pressing

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Journal of Materials Science & Technology 2015年第11期31卷 1151-1157页

作者： X.G.Zheng Y.-N.Shi l.h.lou Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Superalloy Division Institute of Metal Research Chinese Academy of Sciences

hot isostatic pressing （hIP） with a pressure of 180 MPa at a temperature of 1170 ℃ was introduced to an investment cast Ni-based superalloy （Mgl） turbocharger blade to explore the healing process of casting pores generated during investment casting. Optical micrograph and scanning electron naicroscopy （SEM） observations indicate that eutectic pores are the main cast defects in the as-cast blade before hIP. These pores normally locate at the solidification front of γ/γ＇ eutectic with a size of a few micrometers to a few tens of micrometers. After hIP for 4 h, most of the pores were closed. Based on phase characteristics, these pores were healed by the formation of γ matrix with finer and irregular-shaped γ＇ precipitates. healing interface can be easily distinguished by SEM. line scan by using energy dispersive X-ray spectroscopy （EDS） reveals a much higher Ti and Al concentration in the healing interface. It is proposed that solute diffusion toward the casting pores during hIP results in the formation of γ, and the much higher concentration of γ＇-forming elements Al and Ti near the healing interface contributes to the precipitation of γ＇ in the healed region in the succeeding cooling process after hIP.

关键词： Superalloy hot isostatic pressing (hIP) healing

Effect of Solidification Condition and Carbon Content on the Morphology of MC Carbide in Directionally Solidified Nickel-base Superalloys

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Journal of Materials Science & Technology 2014年第12期30卷 1296-1300页

作者： X.W.li l.Wang J.S.Dong l.h.lou Superalloys Division Institute of Metal Research Chinese Academy of Sciences

Evolution of the morphology of MC carbides with the change of cooling rate and carbon content in two kinds of nickel-base superalloys, K417 G and DD33, has been investigated. The morphology of MC carbides evolves from faceted to script-like with increasing cooling rate. Varying the carbon content from 40X10-6 to 320X10-6, the morphology of carbides changes from blocky, rod-like into script-like. Scanning electron microscopy observation of deep-etched samples indicates that these carbides evolve from octahedral to dendritic and then into welldeveloped dendrites accordingly in a three-dimensional manner. The morphology evolution is discussed from the viewpoint of the preferential growth orientation of fcc crystals and the carbide growth rate during directional solidification.

关键词： Carbides morphology Directional solidification Three-dimensional microstructure Nickel-base superalloys

Microstructural evolution of aluminum alloy during friction stir welding under different tool rotation rates and cooling conditions

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Journal of Materials Science & Technology 2019年第6期35卷 972-981页

作者： X.h. Zeng P. Xue l.h. Wu D.R. Ni B.l. Xiao K.S. Wang Z.Y. Ma Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China University of Chinese Academy of Sciences Beijing 100049 China School of Metallurgical Engineering Xi'an University of Architecture and Technology Xi'an 710055 China

The microstructural evolution during friction stir welding(FSW) has long been studied only using one single welding parameter. Conclusions were usually made based on the final microstructure observation and hence were one-sided. In this study, we used the "take-action" technique to freeze the microstructure of an Al-Mg-Si alloy during FSW, and then systematically investigated the microstructures along the material flow path under different tool rotation rates and cooling conditions. A universal characteristic of the microstructural evolution including four stages was identified, i.e. dynamic recovery(DRV), dislocation multiplication, new grain formation and grain growth. however, the dynamic recrystallization(DRX)mechanisms in FSW depended on the welding condition. For the air cooling condition, the DRX mechanisms were related to continuous DRX associated with subgrain rotation and geometric DRX at high and low rotation rates, respectively. Under the water cooling condition, we found a new DRX mechanism associated with the progressive lattice rotation resulting from the pinning of the second-phase *** on the analyses of the influencing factors of grain refinement, it was clearly demonstrated that the delay of DRV and DRX was the efficient method to refine the grains during FSW. Besides, ultra-high strain rate and a short duration at high temperatures were the key factors to produce an ultrafine-grained material.

关键词： Aluminum alloys Grain refinement Dynamic recrystallization Severe plastic deformation Friction stir welding

Silk-based nerve guidance conduits with macroscopic holes modulate the vascularization of regenerating rat sciatic nerve

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Neural Regeneration Research 2025年第6期20卷 1789-1800页

作者： Carina hromada Patrick heimel Markus Kerbl lászlóGál Sylvia Nürnberger Barbara Schaedl James Ferguson Nicole Swiadek Xavier Monforte Johannes C.heinzel Antal Nógrádi Andreas h.Teuschl-Woller David hercher Department life Science Engineering University of Applied Sciences Technikum WienViennaAustria Austrian Cluster for Tissue Regeneration ViennaAustria ludwig Boltzmann Institute for Traumatology The Research Center in Cooperation with AUVAViennaAustria University Clinic of Dentistry Medical University of ViennaViennaAustria Department of Plastic Reconstructive and Aesthetic SurgeryLandesklinikum Wiener Neustadt2700 Wiener NeustadtAustria Department of Anatomy Histology and EmbryologyAlbert Szent-Györgyi Medical SchoolUniversity of SzegedSzegedHungary Medical University of Vienna Department of Orthopedics and Trauma SurgeryDevision of Trauma SurgeryViennaAustria Department of hand- PlasticReconstructive and Burn SurgeryBG Unfallklinik TuebingenUniversity of TuebingenTuebingenGermany

Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). however, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimizatio

关键词： axon regeneration blood vessel functional recovery macroporous nerve lesion peripheral nerve repair sciatic nerve silk-based nerve guidance conduit vascularization

MAKING DUCTIlE CAST IRON WITh ESR PROCESS

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Acta Metallurgica Sinica(English letters) 1998年第3期11卷 169-174页

作者： S.J.Chu h.h.lou Q.Niu Univ of Science and Technology Beijing Beijing China

Making ductile cast iron with ESR process under D.C. condition without adding spheroidizing inoculant alloys has been studied in laboratory. The key operation of ESR for cast iron is increasing the silicon content in unrefined consumable electrodes of flake graphite cast iron and using CaF2-based slags containing rare-earth or basic oxides and magnesium fluoride. The samples excel ductile cast iron produced by general technological process in fatigue strength and sealing performance.

关键词： ductile cast iron electroslag remelting nodulizing element