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Rapid Synthesis of W–Cr Solid–Solution by Dielectric-Barrier Discharge-Plasma-Assisted Ball Milling
S. F. Hong,Z. C. Lu,Y. H. Liu,Q. M. He,W. Jiang,M. Q. Zeng 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12
Supersaturated solid–solutions in a W–Cr alloy system were fabricated by conventional milling and plasma milling. The differentextension mechanisms of the solid solubility that were created by ball milling with and without discharge plasma werestudied. The solid–solubility of Cr in W for the P-milling W–Cr alloy system was higher, which indicates that plasma millingpromotes the formation of W(Cr) solid–solution more easily than conventional milling. According to Miedema’s model, inthe W–Cr alloy system, the free-energy change to form a W(Cr) solid solution by plasma milling is reduced compared withconventional milling because of the heating effect of the discharge plasma. Therefore, a higher stored energy in the grainboundaries and dislocations of the W–Cr nanograins during plasma milling makes it easier to overcome the thermodynamicbarrier in the formation of a solid–solution, when compared with conventional milling.
M. Q. Zeng,J. L. Tu,M. Zhu,W. Wang,J. W. Liu,Z. C. Lu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9
The effects of plasma discharge intensity on the microstructure evolution of ball-milled tungsten (W)–carbon (C)–cobalt (Co)mixtures and the formation mechanism of ultrathin plate-like tungsten carbide (WC) grains prepared by ball milling with andwithout plasma discharge were investigated. It was found that increasing the plasma discharge intensity during ball millingobviously promoted the formation of a thin flake-like W phase because of the electroplasticity effect and simultaneouslylowered the carburization temperature between W and C. A combination of high hardness and transverse rupture strength of92.9 HRA and 3659 MPa, respectively, was obtained for the WC–8Co alloy fabricated by plasma milling at a gas pressure of5 × 103 Pa with a dielectric barrier discharge layer thickness of 3 mm. These properties were mainly attributed to the markedlylowered activation energy of the WC phase and generation of highly oriented ultrathin plate-like WC grains by plasma milling. The combination of the flake-like structure of the plasma-milled W aggregate and high specific interfacial area and shortdiffusion distance of W/C were readily inherited by the ultrathin plate-like WC grains in the sintered WC–Co hardmetals.
병렬형 하이브리드 자동차의 SimulationX 모델 개발 및 연비 시뮬레이션
서영우(Y. W. Seo),한성민(S. M. Han),여현승(H. S. Yeo),이석우(S. W. Lee),류하오(Hao Liu) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.12
Hybrid Electric Vehicles (HEVs) are an important seed in the process of converting from traditional internal combustion engine vehicles to eco-friendly vehicles. HEVs that use two energy sources have a complex structure, and thus, these two energy sources work independently/alternatively/jointly depending on road driving conditions in order to improve fuel efficiency. As HEVs are developed, it is becoming important to understand the operating principles and to interpret fuel economy performance in simulations. This research used simulationX, a commercial multi-domain analysis S/W, to develop a model for a parallel type hybrid vehicles, and implement fuel efficiency analysis. First, the heat engine, battery, electric motor, power train, etc. were modeled in a simulationX environment based on the parallel hybrid vehicle structure. Then, fuel efficiency analysis simulation was performed on driving condition of NEDC (New European Driving Cycle). The developed simulationX model for parallel type hybrid vehicle is prepared to develop a controller for fuel efficiency improvement in the future work.
SimulationX 기반 자동차 semi-active 현가장치의 모델 개발 및 특성 해석
정인태(I. T. Jeong),정동석(D. S. Jeong),정원식(W. S. Jeong),이성민(S. M. Lee),유보연(B. Y. Yoo),장대범(D. B. Jang),서영우(Y. W. Seo),한성민(S. M. Han),이석우(S. W. Lee),여현승(H. S. Yeo),류하오(Hao Liu) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.12
The semi-active suspension system controls the damping force of the vehicle damper to simultaneously improve the steering stability (handling) and ride comfort of the vehicle. In order to improve the ride comfort of a passenger car, performance analysis is required through modeling and simulation adaptation of a semi-active suspension system. This study used SimulationX, a commercial multi-domain analysis S/W, and modeling about 1/4 car of the semi-active suspension system. The damping force was controlled through a given performance of the damper. The developed SimulationX-based semi-active suspension system model is prepared for future controller development research.
Multivone모델을 이용한 분사율 변화에 따른 직접분사식 디젤엔진의 배기가스 특성 예측에 관한 연구
황재원(J.W.Hwang),박재근(J.H.Park),갈한주(H.J.Kal),김만호(M.H.Kim),Liu Sheghua(Liu Shemghua),채재우(J.O.Chae) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
A multizone phenomenological combustion model, in which the burn rate is governed by the rate of fuel vaporization and mixing, is developed to study the effects of fuel injection rate shapes on exhaust emissions of direct injection diesel engines. The extended Zel'dovich mechanism is used to estimate the NO formation. This model is calibrated with the experimental data. Comparison between the results calculated by the model and experimental results shows that the model has a good predictive capability for cylinder pressure, heat release rate and exhaust emissions. And this study was investigated according to injection rate shapes. The results predicted by the model show that fuel amount of premixed combustion affects NO formation and NO is reduced by 14% with soot 7% increased at 1900rpm 50% load condition.<br/>