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Multi-feeder 3차원 적층제조 기반 조합실험을 활용한 알루미늄 합금탐색
박수원,송용욱,여지윤,한송윤,최현주 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
Aluminum alloys are widely utilized in diverse industries, such as automobiles, aerospace, and architecture, owing to their high specific strength and resistance to oxidation. However, to meet the increasing demands of the industry, it is necessary to design new aluminum alloys with excellent properties. Thus, a new method is required to efficiently test additively manufactured aluminum alloys with various compositions within a short period during the alloy design process. In this study, a combinatory approach using a direct energy deposition system for metal 3D printing process with a dual feeder was employed. Two types of aluminum alloy powders, namely Al6061 and Al-12Cu, were utilized for the combinatory test conducted through 3D printing. Twelve types of Al-Si-Cu-Mg alloys were manufactured during this combinatory test, and the relationship between their microstructures and properties was investigated.
레이저 분말 베드 용융법으로 제조된 AlSi10Mg 합금의 경도 예측을 위한 설명 가능한 인공지능 활용
전준협,서남혁,김민수,손승배,정재길,이석재 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
In this study, machine learning models are proposed to predict the Vickers hardness of AlSi10Mg alloys fabricated by laser powder bed fusion (LPBF). A total of 113 utilizable datasets were collected from the literature. The hyperparameters of the machine-learning models were adjusted to select an accurate predictive model. The random forest regression (RFR) model showed the best performance compared to support vector regression, artificial neural networks, and k-nearest neighbors. The variable importance and prediction mechanisms of the RFR were discussed by Shapley additive explanation (SHAP). Aging time had the greatest influence on the Vickers hardness, followed by solution time, solution temperature, layer thickness, scan speed, power, aging temperature, average particle size, and hatching distance. Detailed prediction mechanisms for RFR are analyzed using SHAP dependence plots.
고강도 Nb기 초내열 합금 설계를 위한 기계학습 기반 데이터 분석
마은호,박수원,최현주,황병철,변종민 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
Machine learning-based data analysis approaches have been employed to overcome the limitations in accurately analyzing data and to predict the results of the design of Nb-based superalloys. In this study, a database containing the composition of the alloying elements and their room-temperature tensile strengths was prepared based on a previous study. After computing the correlation between the tensile strength at room temperature and the composition, a material science analysis was conducted on the elements with high correlation coefficients. These alloying elements were found to have a significant effect on the variation in the tensile strength of Nb-based alloys at room temperature. Through this process, a model was derived to predict the properties using four machine learning algorithms. The Bayesian ridge regression algorithm proved to be the optimal model when Y, Sc, W, Cr, Mo, Sn, and Ti were used as input features. This study demonstrates the successful application of machine learning techniques to effectively analyze data and predict outcomes, thereby providing valuable insights into the design of Nb-based superalloys.
생체모방 모세관 현상을 이용한 PDMS 구조체 기반 증산발전기 제조기술 연구
이승환,윤정재,백소현,권용범,송요셉,김범성,좌용호,정다운 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
The demand for energy is steadily rising because of rapid population growth and improvements in living standards. Consequently, extensive research is being conducted worldwide to enhance the energy supply. Transpiration power generation technology utilizes the vast availability of water, which encompasses more than 70% of the Earth's surface, offering the unique advantage of minimal temporal and spatial constraints over other forms of power generation. Various principles are involved in water-based energy harvesting. In this study, we focused on explaining the generation of energy through the streaming potential within the generator component. The generator was fabricated using sugar cubes, PDMS, carbon black, CTAB, and DI water. In addition, a straightforward and rapid manufacturing method for the generator was proposed. The PDMS generator developed in this study exhibits high performance with a voltage of 29.6 mV and a current of 8.29 μA and can generate power for over 40h. This study contributes to the future development of generators that can achieve high performance and long-term power generation.
자전연소합성법을 이용한 Cr 분말 제조시 산세조건에 따른 물성평가
이용관,조영우,최신영,허성규,주 원,박경태,이미혜,심재진 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.
The Effect of SnO2 Addition on Sintering Behaviors in a Titanium Oxide-Copper Oxide System
이주원,오경식,정태주,백용균 한국분말재료학회 2022 한국분말재료학회지 (KPMI) Vol.29 No.5
The low-temperature sinterability of TiO2-CuO systems was investigated using a solid solution of SnO2. Sample powders were prepared through conventional ball milling of mixed raw powders. With the SnO2 content, the compositions of the samples were Ti1-xSnxO2-CuO(2 wt.%) in the range of x 0.08. Compared with the samples without SnO2 addition, the densification was enhanced when the samples were sintered at 900oC. The dominant mass transport mechanism seemed to be grain-boundary diffusion during heat treatment at 900oC, where active grain-boundary diffusion was responsible for the improved densification. The rapid grain growth featured by activated sintering was also obstructed with the addition of SnO2. This suggested that both CuO as an activator and SnO2 dopant synergistically reduced the sintering temperature of TiO2.
IN718 초내열 합금의 고속 적층 제조 속도 확보를 위한 최적 VED 활용 공정 변수 제어 방안 연구
김상욱,김규식,손용호,이기안 한국분말재료학회 2022 한국분말재료학회지 (KPMI) Vol.29 No.5
Recently, considerable attention has been given to nickel-based superalloys used in additive manufacturing. However, additive manufacturing is limited by a slow build rate in obtaining optimal densities. In this study, optimal volumetric energy density (VED) was calculated using optimal process parameters of IN718 provided by additive manufacturing of laser powder-bed fusion. The laser power and scan speed were controlled using the same ratio to maintain the optimal VED and achieve a fast build rate. Cube samples were manufactured using seven process parameters, including an optimal process parameter. Analysis was conducted based on changes in density and melt-pool morphology. At a low laser power and scan speed, the energy applied to the powder bed was proportional to and not . At a high laser power and scan speed, a curved track was formed due to Plateau-Rayleigh instability. However, a wide melt-pool shape and continuous track were formed, which did not significantly affect the density. We were able to verify the validity of the VED formula and succeeded in achieving a 75% higher build rate than that of the optimal parameter, with a slight decrease in density and hardness.
조현희,이서현,윤은서,서지은,이진우,한동훈,남서아,한정환 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.1
Atomic layer etching (ALE) is a promising technique with atomic-level thickness controllability and high selectivity based on self-limiting surface reactions. ALE is performed by sequential exposure of the film surface to reactants, which results in surface modification and release of volatile species. Among the various ALE methods, thermal ALE involves a thermally activated reaction by employing gas species to release the modified surface without using energetic species, such as accelerated ions and neutral beams. In this study, the basic principle and surface reaction mechanisms of thermal ALE?processes, including “fluorination-ligand exchange reaction”, “conversion-etch reaction”, “conversion-fluorination reaction”, “oxidation-fluorination reaction”, “oxidation-ligand exchange reaction”, and “oxidation-conversion-fluorination reaction” are described. In addition, the reported thermal ALE processes for the removal of various oxides, metals, and nitrides are presented.
IN 939 W 합금의 소결 승온 속도에 따른 물리적 특성과 미세조직 분석
전준협,이준호,서남혁,손승배,정재길,이석재,Jeon, Junhyub,Lee, Junho,Seo, Namhyuk,Son, Seung Bae,Jung, Jae-Gil,Lee, Seok-Jae 한국분말재료학회 (*구 분말야금학회) 2022 한국분말재료학회지 (KPMI) Vol.29 No.5
Changes in the mechanical properties and microstructure of an IN 939 W alloy according to the sintering heating rate were evaluated. IN 939 W alloy samples were fabricated by spark plasma sintering. The phase fraction, number density, and mean radius of the IN 939 W alloy were calculated using a thermodynamic calculation. A universal testing machine and micro-Vickers hardness tester were employed to confirm the mechanical properties of the IN 939 W alloy. X-ray diffraction, optical microscopy, field-emission scanning electron microscopy, Cs-corrected-field emission transmission electron microscopy, and energy dispersive X-ray spectrometry were used to evaluate the microstructure of the alloy. The rapid sintering heating rate resulted in a slightly dispersed γ' phase and chromium oxide. It also suppressed the precipitation of the η phase. These helped to reinforce the mechanical properties.