• 제목/요약/키워드: Gas Atomization

검색결과 385건 처리시간 0.021초

Investigation on Microstructure and Flowability of Gas Atomized Heat-resistant KHR45A Alloy Powders for Additive Manufacturing

  • Geonwoo Baek;Mohsen Saboktakin Rizi;Yeeun Lee;SungJae Jo;Joo-Hyun Choi;Soon-Jik Hong
    • 한국분말재료학회지
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    • 제30권1호
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    • pp.13-21
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    • 2023
  • In additive manufacturing, the flowability of feedstock particles determines the quality of the parts that are affected by different parameters, including the chemistry and morphology of the powders and particle size distribution. In this study, the microstructures and flowabilities of gas-atomized heat-resistant alloys for additive manufacturing applications are investigated. A KHR45A alloy powder with a composition of Fe-30Cr-40Mn-1.8Nb (wt.%) is fabricated using gas atomization process. The microstructure and effect of powder chemistry and morphology on the flow behavior are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and revolution powder analysis. The results reveal the formation of spherical particles composed of single-phase FCC dendritic structures after gas atomization. SEM observations show variations in the microstructures of the powder particles with different size distributions. Elemental distribution maps, line scans, and high-resolution XPS results indicate the presence of a Si-rich oxide accompanied by Fe, Cr, and Nb metal oxides in the outer layer of the powders. The flowability behavior is found to be induced by the particle size distribution, which can be attributed to the interparticle interactions and friction of particles with different sizes.

음향에너지를 이용한 내부 혼합형 이유체 분사노즐의 분무특성 (Spray Characteristics of Internal-Mixing Twin-Fluid Atomizer using Sonic Energy)

  • 조형건;강원수;석지권;이근선;이충원
    • 한국분무공학회지
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    • 제4권3호
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    • pp.32-41
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    • 1999
  • In this research, internal-mixing twin-fluid atomizer using sonic energy is designed and manufactured. We are trying to intimate high efficiency twin-fluid atomizer to obtain good liquid atomization in the low pressure region. Define of geometric form of atomizer, characteristics of spray is influenced by position, depth and height variation of cavity resonator, variation of sound intensity and resonant sound frequency with liquid flow rate. The liquid atomization is promoted by multi-stage disintegration of mixing flow of gas with liquid and the optimum condition of position and depth of cavity resonator according to sonic energy is obtained from the condition at a=2.5mm and L=2mm. The velocity distribution of droplets shows negative value due to recirculation region at the center of axial, and as the radial direction distance is far, the velocity distribution of droplets decrease slowly after having a maximum value. However velocity and SMD show nearly uniform distribution at the down stream and as result compared to Nukiyama and Tanasawa's equation. atomization of mixing flow with air and liquid dispersing from the outlet of the nozzle is promoted by the effect of collision at the cavity resonator.

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가스 분사법으로 제조한 Mg-Zn-Y 합금의 플라즈마 전해 산화 피막 특성에 관한 연구 (Characteristics of Plasma Electrolytic Oxidation Coatings on Mg-Zn-Y Alloys Prepared by Gas Atomization)

  • 장시영;조한경;이두형;김택수
    • 한국분말재료학회지
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    • 제14권6호
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    • pp.372-379
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    • 2007
  • The microstructure, mechanical and electrochemical properties of plasma electrolytic coatings (PEO) coatings on Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn-2.0 wt%Y alloys prepared by gas atomization, followed by compaction at 320 for 10 min under the pressure of 700 MPa and sintering at 380 and 420 respectively for 24 h, were investigated, which was compared with the cast Mg-1.0 wt%Zn alloy. All coatings consisting of MgO and $Mg_2SiO_4$ oxides showed porous and coarse surface features with some volcano top-like pores distributed disorderly and cracks between pores. In particular, the surface of coatings on Mg-1.0 wt%Zn-2.0 wt%Y alloy showed smaller area of pores and cracks compared to the Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn alloys. The cross section micro-hardness of coatings on the gas atomized Mg-Zn-Y alloys was higher than that on the cast Mg-1.0 wt%Zn alloy. Additionally, the coated Mg-1.0 wt%Zn-2.0 wt%Y alloy exhibited the best corrosion resistance in 3.5%NaCl solution. It could be concluded that the addition of Y has a beneficial effect on the formation of protective and hard coatings on Mg alloys by plasma electrolytic oxidation treatment.

가스발생기용 F-O-F 충돌형 인젝터 분사특성 (Atomization Characteristic of F-O-F Triplet Injector for Gas Generator)

  • 권순탁;이창진;김승한;한영민
    • 한국항공우주학회지
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    • 제33권1호
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    • pp.62-68
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    • 2005
  • 액체로켓 가스발생기를 위한 인젝터를 설계하여 분사특성을 살펴보았다. 인젝터는 F-O-F triplet impinging이고 모의 추진제로 kerosene/물을 사용하였다. 인젝터의 형상설계 변수는 충돌각과 충돌거리이며 이를 이용하여 5가지의 후보 요소 인젝터를 설계하였으며, 모의 추진제를 사용하여 분사 특성을 실험하였다. 분사특성을 측정하기 위한 인자는 혼합효율과 분사각으로 모의 추진제 운동량비 0.2~1.3 범위에서 분사유량과 국부 O/F비를 측정하고 혼합효율을 계산하였다. 가스발생기용 인젝터는 농염한계의 O/F비 때문에 가장 높은 효율과 적절한 분사 각을 갖는 요소 인젝터를 선정하였고 연소 특성을 연구하기 위하여 연소실험을 실시하였다.

Gas atomization으로 제조된 Ti50Ni30Cu20 합금 분말의 상변태 거동 (Martensitic Transformation Behaviors of Gas Atomized Ti50Ni30Cu20 Powders)

  • 김연욱;정영수;최은수;남태현;임연민
    • 한국주조공학회지
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    • 제31권1호
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    • pp.26-30
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    • 2011
  • For the fabrication of bulk near-net-shape Ti-Ni-Cu shape memory alloys, consolidation of Ti-Ni-Cu alloy powders are useful because of their brittle property. In the present study, $Ti_{50}Ni_{30}Cu_{20}$ shape memory alloy powders were prepared by gas atomization and martensitic transformation temperatures and microstructures of those powders were investigated as a function of powder size. The size distribution of the powders was measured by conventional sieving, and sieved powders with the specific size range of 25 to $150\;{\mu}m$ were chosen for this examination. XRD analysis showed that the B2-B19 martensitic transformation occurred in the powders. In DSC curves of the as-atomized $Ti_{50}Ni_{30}Cu_{20}$ powders as a function of powder size, only one clear peak was found on each cooling and heating curve. The martensitic transformation start temperature($M_s$) of the $25-50\;{\mu}m$ powders was $31.5^{\circ}C$. The $M_s$ increased with increasing powder size and the difference of $M_s$ between $25-50\;{\mu}m$ powders and $100-150\;{\mu}m$ powders is only $1^{\circ}C$. The typical microstructure of the rapidly solidified powders showed cellular morphology and very small pores were observed in intercellular regions.

Optimization of VIGA Process Parameters for Power Characteristics of Fe-Si-Al-P Soft Magnetic Alloy using Machine Learning

  • Sung-Min, Kim;Eun-Ji, Cha;Do-Hun, Kwon;Sung-Uk, Hong;Yeon-Joo, Lee;Seok-Jae, Lee;Kee-Ahn, Lee;Hwi-Jun, Kim
    • 한국분말재료학회지
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    • 제29권6호
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    • pp.459-467
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    • 2022
  • Soft magnetic powder materials are used throughout industries such as motors and power converters. When manufacturing Fe-based soft magnetic composites, the size and shape of the soft magnetic powder and the microstructure in the powder are closely related to the magnetic properties. In this study, Fe-Si-Al-P alloy powders were manufactured using various manufacturing process parameter sets, and the process parameters of the vacuum induction melt gas atomization process were set as melt temperature, atomization gas pressure, and gas flow rate. Process variable data that records are converted into 6 types of data for each powder recovery section. Process variable data that recorded minute changes were converted into 6 types of data and used as input variables. As output variables, a total of 6 types were designated by measuring the particle size, flowability, apparent density, and sphericity of the manufactured powders according to the process variable conditions. The sensitivity of the input and output variables was analyzed through the Pearson correlation coefficient, and a total of 6 powder characteristics were analyzed by artificial neural network model. The prediction results were compared with the results through linear regression analysis and response surface methodology, respectively.

디젤 및 DME 연료의 거시적 분무특성 비교 (Comparisons of Diesel and DME Fuel in Macroscopic Spray Characteristics)

  • 박준규;전문수;박성욱
    • 한국분무공학회지
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    • 제17권4호
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    • pp.205-209
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    • 2012
  • This study focused on comparing macroscopic characteristics of DME and diesel fuel experimentally. DME fuel is one of the most promising alternative fuels because of its superiority in atomization characteristic and clearness in terms of exhaust gas compared with existing fossil fuels. In addition, DME fuel has high cetane number so it could be applied to compression ignition engine. However because DME fuel exists in gas phase at room temperature and atmospheric pressure, and it corrodes rubber parts of fuel line, DME fuel is hard to apply to commercial vehicles. To establish knowledge about DME fuel and furthermore, to develop commercial DME vehicles such as passenger cars, many research have been proceeded steadily. The present study, by comparing spray characteristics of DME fuel to those of diesel fuel, improved atomization characteristics in DME were revealed. Injection quantity measurement and spray visualization experiment were progressed and it was revealed that DME fuel shows small injection quantity than that of diesel fuel and axial development of spray in terms of spray tip penetration decreases when DME fuel was injected.

소형가스터빈용 인젝터의 분무 특성에 따른 반응 유동장 전산 해석 (Numerical Simulation on a Reacting Flow Field with Various Injection conditions)

  • 김세환;정인석;박희호;나상권
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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    • pp.300-303
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    • 2010
  • 항공용 저출력 소형 가스터빈 엔진에 적용을 위한 연료 분사기의 분무 특성에 따른 반응 유동장에 대한 수치해석을 수행하였다. 인젝터의 개발에 있어 연료의 분무 상태가 엔진 성능에 큰 영향을 미치므로 다양한 변수에 대한 고려가 요구되고 있다. 본 연구에서는 정지 상태의 유동장에 분사기를 위치시키고 액적의 평균 직경, 분사 압력, 분사각을 변경하며 그에 따른 반응 특성을 살펴보았다. 해석 결과 분사압과 분사 각도가 클수록, 액적의 직경이 작을수록 활발한 반응이 일어나지만 분사압이 큰 경우 영역내에서 기화되는 연료량이 감소함을 확인할 수 있었다.

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SECFR 시스템의 차량적용을 위한 분무균일도향상에 관한 연구 (A Study for Improving Spray Uniformity of the SECFR System for Vehicle Applications)

  • 손정욱;우승철;김수겸;이기형
    • 한국분무공학회지
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    • 제20권2호
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    • pp.95-100
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    • 2015
  • Lower recirculated gas temperature at EGR system reduces NOx and PM emissions. However, EGR Cooler can be polluted by PM generated from recirculated EGR gas, and it reduces cooling efficiency and the amount of EGR gas simultaneously. The SECFR(Steam EGR Cooler Fouling Remover) system which uses the evaporated washer fluid steam caused by high temperature of EGR gas was manufactured for removing fouling generated on the cooler surface. Since an injection pressure of wind shield washer fluid in the vehicle is approximately 0.5 bar, it is not enough to atomize the injected washer fluid. Thus, it is necessary to apply a method to atomize the washer fluid. In this study, the impinging plate was used to promote the atomization of spray washer fluid for the purpose of apply SECFR system to vehicles and measured the DAR(Droplet Area Ratio) and DUI(Droplet Uniformity Index) through the spray visualization.