检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

韩国粉末冶金工业

粉末冶金工业 2006年第2期16卷 31-33页

作者：金镇千金柄淇韩国机械与材料研究院

韩国粉末冶金工业有大约40年的历史,在过去10年中,年平均递增率达到15%,2003年韩国有约440家粉末冶金公司;汽车工业的飞速发展推动了粉末冶金结构零件的发展,韩国每辆小汽车上用约70个粉末冶金零件,略大于6.5 kg,2003年铁粉消耗量达到5... 详细信息

韩国粉末冶金工业有大约40年的历史,在过去10年中,年平均递增率达到15%,2003年韩国有约440家粉末冶金公司;汽车工业的飞速发展推动了粉末冶金结构零件的发展,韩国每辆小汽车上用约70个粉末冶金零件,略大于6.5 kg,2003年铁粉消耗量达到5万吨以上,约63%的铁粉从瑞典进口;粉末冶金产品的总产值达到23亿美元,进出口约7亿美元。

关键词：韩国粉末冶金铁粉

Stabilized sub-grain and nano carbides-driven 1.2 GPa grade ultra-strong CrMnFeCoNi high-entropy alloy additively manufactured by laser powder bed fusion

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第22期117卷 8-22页

作者： Young-Kyun kim kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Institute of Materials Science(kimS) Changwon 51508Republic of Korea

High-entropy alloys(HEAs)with interstitial atoms that are produced by additive manufacturing have gained intensive interest in the materials science community because of their suitability for constructing high-strength net-shape ***,a strategy to additionally enhance the strength of selective laser melted carbon-containing HEAs was *** as-built carbon-containing HEAs(C_(x)(Cr_(20)Mn_(20)Fe_(20)Co_(20)Ni_(20))_(100-x)(x=0.5 at.%,1.0 at.%,and 1.5 at.%))contain supersaturated carbon,and the extent of supersaturation increases as the carbon content *** subjected to aging treatment at 650°C for 1 h,the microstructure of the three alloys did not change at the grain ***,the microstructure at the sub-grain scale changed markedly,and these changes influenced the tensile properties and deformation *** particular,the tensile strength of aged 1.5C-HEA at 650°C was∼1.2 GPa at room temperature,which is higher than those reported for CrMnFeCoNi ***,the main deformation mechanism changed from deformation twinning to dislocation-mediated slip,resulting in much higher strain hardening capacity after the aging *** work led to the development of an alternative promising method that involves tailoring the microstructure,to enhance the mechanical properties of additively manufactured metallic materials that contain interstitial atoms.

关键词： Selective laser melting High-entropy alloy Carbon contents Aging Microstructure evolution Tensile property Deformation mechanism

Effect of carrier gas species on the microstructure and compressive deformation behaviors of ultra-strong pure copper manufactured by cold spray additive manufacturing

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第2期97卷 264-271页

作者： Young-Kyun kim kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea

Cold spray(CS)which has recently become a promising additive manufacturing(AM)technology,was used to fabricate ultra-strong pure *** addition,the effects of carrier gas species on the microstructural characteristics,mechanical properties and deformation mechanisms were systemically *** CSAM copper manufactured with N_(2) carrier gas reveals a heterogeneous bimodal microstructure consisting of ultra-fine grains at the particle interface and relatively coarse grains in inner *** He carrier gas,a homogeneous grain structure consisting of ultra-fine grains in most areas was *** tests showed that N_(2) and He carrier gasses enabled ultra-high yield strengths of 340 and415 MPa,*** values are comparable to severely plastic deformed copper,which has extremely low ductility and shape *** the other hand,both samples showed a strain-softening phenomenon that does not commonly occur at room *** deformation microstructures revealed that dynamic recovery(DRV)and dynamic recrystallization(DRX)phenomena were generated despite being deformed at room *** on the above findings,the overall deformation mechanisms according to the carrier gas species in the CSAM copper manufacturing process were ***,the work hardening and softening behaviors of CSAM Cu are predicted by using a constitutive equation.

关键词： Cold spray additive manufacturing Carrier gas Pure Cu Mechanical properties Deformation behavior

1.45 GPa ultrastrong cryogenic strength with superior impact toughness in the in-situ nano oxide reinforced CrMnFeCoNi high-entropy alloy matrix nanocomposite manufactured by laser powder bed fusion

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第2期97卷 10-19页

作者： Young-Kyun kim Min-Chul kim kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Atomic Energy Research Institute(KAERI) Daejeon 34057Republic of Korea

CrMnFeCoNi high-entropy alloys(HEAs)exhibit an excellent combination of tensile strength and ductility at cryogenic *** study led to the introduction of a new method for the development of high-performance CrMnFeCoNi HEAs at cryogenic temperatures by jointly utilizing additive manufacturing(AM)and the addition of interstitial *** interstitial oxygen present in the powder feedstock was transformed into beneficial nano-sized oxides during AM *** HEA nanocomposite fabricated using laser powder bed fusion(L-PBF)not only contains heterogeneous grains and substructures but also a high number density of nano-sized *** tensile results revealed that the L-PBF HEA nanocomposite has superior yield strengths of 0.77 GPa and 1.15 GPa,and tensile strengths of 0.92 GPa and 1.45 GPa at 298 K and 77 K,*** addition,the Charpy impact energies of the samples tested at 298 K and 77 K were measured as 176.2 J and 103.7 J,*** results indicate that the L-PBF HEA nanocomposite successfully overcomes the well-known strength-toughness *** tensile deformation microstructure contained a relatively large number of deformation twins(DTs)at cryogenic temperature,a possible consequence of the decrease in the stacking fault energy with decreasing *** the other hand,cracks were found to propagate along the grain boundaries at room temperature,whereas a transgranular crack was observed at cryogenic temperature in the specimens fractured as a result of the Charpy impact.

关键词： Laser powder bed fusion High-entropy alloy matrix nanocomposite Nano-oxide:cryogenic Tensile Impact toughness

Numerical Analysis of Secondary Cooling in Continuous Slab Casting

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第3期24卷 389-390页

作者： kee-Hyeon Cho Byung-Moon kim Research Institute of Industrial Science & Technology GyeongBuk Regional Stragetic Agency for Innovation

In the present study, a numerical optimization program has been developed for predicting the optimal secondary cooling patterns in a continuous slab caster. Optimization strategy using Broydon-Fletcher-Goldfarb-Shanno （13FGS） method is carried out by determining the constant heat transfer coefficients in each spray zone, which could satisfy the casting conditions and metallurgical criteria specified by the engineer. From the present results, it is found that even a slight variation in the pouring temperature, allowable surface temperature, and casting speed could give rise to the changes in the cooling pattern throughout the spray zones.

关键词： Continuous casting Secondary cooling Optimization

Effect of post heat-treatment on the microstructure and high-temperature oxidation behavior of precipitation hardened IN738LC superalloy fabricated by selective laser melting

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第17期76卷 95-103页

作者： Kyu-Sik kim Sangsun Yang Myeong-Se kim kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Institute of Materials Science Changwon51508Republic of Korea Auratech Co. Ltd.Seongnam13449Republic of Korea

The present study investigated the effect of as-built and post heat-treated microstructures of IN738LC alloy fabricated via selective laser melting process on high temperature oxidation *** as-built microstructure showed fine cell and columnar structure due to high cooling *** element segregation was observed in inter-cell/inter-columnar *** post heat-treatment,the initially-observed cell structure disappeared,instead bimodal Ni_3(Al,Ti)particles *** temperature(1273 K and 1373 K)oxidation test results showed parabolic oxidation curves regardless of temperature and initial *** as-built IN738LC fabricated via the selective laser melting process displayed oxidation resistance similar to or slightly better than that of IN738LC fabricated via wrought or cast ***-treated SLM IN738LC,although had similar oxidation weight-gain values to those of the SLM asbuilt material at 1273K,showed relatively better oxidation resistance at 1373 *** Ni_3(Al,Ti)precipitate formed in the post heat treatment changed the local chemical composition,thereby led to changes in alumina former/chromia former location and fraction on the alloy *** was concluded that in heat-treated IN738LC increased alumina former fraction was found,and this resulted in excellent oxidation resistance and relatively low weight-gain.

关键词： IN738LC Selective laser melting High temperature oxidation Post heat-treatment Oxidation mechanism

Recent Advances in Patterning Strategies for Full‑Color Perovskite Light‑Emitting Diodes

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2024年第3期16卷 99-137页

作者： Gwang Heon Lee Kiwook kim Yunho kim Jiwoong Yang Moon kee Choi Graduate School of Semiconductor Materials and Devices Engineering Center for Future Semiconductor Technology(FUST)Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Republic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea Energy Science and Engineering Research Center Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea Department of Materials Science and Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Republic of Korea Center for Nanoparticle Research Institute for Basic Science(IBS)Seoul 08826Republic of Korea

Metal halide perovskites have emerged as promising light-emitting materials for next-generation displays owing to their remarkable material characteristics including broad color tunability,pure color emission with remarkably narrow bandwidths,high quantum yield,and solution *** recent advances have pushed the luminance efficiency of monochromic perovskite light-emitting diodes(PeLEDs)to their theoretical limits,their current fabrication using the spincoating process poses limitations for fabrication of full-color *** integrate PeLEDs into full-color display panels,it is crucial to pattern red–green–blue(RGB)perovskite pixels,while mitigating issues such as cross-contamination and reductions in luminous ***,we present state-of-the-art patterning technologies for the development of full-color ***,we highlight recent advances in the development of efficient ***,we discuss various patterning techniques of MPHs(i.e.,photolithography,inkjet printing,electron beam lithography and laserassisted lithography,electrohydrodynamic jet printing,thermal evaporation,and transfer printing)for fabrication of RGB pixelated *** patterning techniques can be classified into two distinct approaches:in situ crystallization patterning using perovskite precursors and patterning of colloidal perovskite *** review highlights advancements and limitations in patterning techniques for PeLEDs,paving the way for integrating PeLEDs into full-color panels.

关键词： Perovskite Light-emitting diode Full-color display High-resolution patterning Electroluminescence

2.47 GPa grade ultra-strong 15Co-12Ni secondary hardening steel with superior ductility and fracture toughness

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第7期66卷 36-45页

作者： Young-Kyun kim Kyu-Sik kim Young-Beum Song Jung Hyo Park kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon22212Republic of Korea Agency for Defense Development(ADD) Yuseong-guDaegeon34186Republic of Korea

This study investigated the effect of multi-step heat treatment on the microstructure, mechanical properties and fracture behavior of thick 15 Co-12 Ni secondary hardening steel. As-quenched sample was found to have elongated prior austenite grain(PAG) and coarse lenticular martensitic structure. On the other hand, heat-treated sample was observed to have fine lenticular martensitic structure due to fine PAG size and a lot of nano-sized carbides. Also, after heat treatment, nano-scale reverted austenite film was formed at the martensite interfaces. The heat-treated sample showed 2.47 GPa superior tensile strength and superior elongation of about 12 %. The high strength was mainly due to fine block size and high number density of nano-sized carbides. The average value of plane strain fracture toughness(KIC) was 29.3 MPa m1/2, which indicated a good fracture toughness even with the high tensile strength. The tensile fracture surface was observed to have ductile fracture mode(cup-and-cone) and the formation of about ~1 μm ultra-fine dimples. In addition to this, nano-sized carbides were observed within the *** findings suggested that the nano-sized carbide had a positive effect not only on the strength but also on the ductility of the alloy. The fractured surface after toughness test, also showed ductile fracture mode with a lot of dimples. Based on the above results, correlation among microstructural evolution,deformation and fracture mechanisms along the heat-treatment was also discussed.

关键词： Ultra-high strength High Co-Ni secondary hardening steel Microstructure Tensile properties Fracture toughness Reverted austenite

Innovative technique of needlescopic grasper-assisted single-incision laparoscopic common bile duct exploration:A comparative study

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第45期21卷 12857-12864页

作者： Say-June kim kee-Hwan kim Chang-Hyeok An Jeong-Soo kim Daejeon St.Mary’s Hospital College of MedicineThe Catholic University of Korea Department of Surgery Uijeongbu St. Mary’s HospitalCollege of MedicineThe Catholic University of Korea

AIM: To investigate the safety and feasibility of needlescopic grasper-assisted single-incision laparoscopic common bile duct exploration(n SIL-CBDE) by comparing the surgical outcomes of this technique with those of conventional laparoscopic CBDE(CL-CBDE).METHODS: We retrospectively analyzed the clinical data of patients who underwent CL-CBDE or n SILCBDE for the treatment of common bile duct(CBD) stones between January 2000 and December 2014. For performing n SIL-CBDE, a needlescopic grasper was also inserted through a direct puncture below the right subcostal line after introducing a single-port through the umbilicus. The needlescopic grasper helped obtain the critical view of safety by retracting the gallbladder laterally and by preventing crossing or conflict between laparoscopic instruments. The gallbladder was then partially dissected from the liver bed and used for retraction. CBD stones were usually extracted through a longitudinal supraduodenal choledochotomy, mostly using flushing a copious amount of normal saline througha ureteral catheter. Afterward, for the certification of CBD clearance, CBDE was performed mostly using a flexible choledochoscope. The choledochotomy site was primarily closed without using a T-tube, and simultaneous cholecystectomies were ***: During the study period, 40 patients underwent laparoscopic CBDE. Of these patients, 20 underwent CL-CBDE and 20 underwent n SIL-CBDE. The operative time for n SIL-CBDE was significantly longer than that for CL-CBDE(238 ± 76 min vs 192 ± 39 min, P = 0.007). The stone clearance rate was 100%(40/40) in both groups. Postoperatively, the n SIL-CBDE group required less intravenous analgesic(pethidine)(46.5 ± 63.5 mg/kg vs 92.5 ± 120.1 mg/kg, P = 0.010) and had a shorter hospital stay than the CL-CBDE group(3.8 ± 2.0 d vs 5.1 ± 1.7 d, P = 0.010). There was no significant difference in the incidence of postoperative complications between the two ***: The results of this study

关键词： Choledocholithiasis Choledochotomy Common bile duc