연속주조에서 Upper Nozzle 막힘지수에 의한 막힘 거동 고찰

김성연 대한금속재료학회 2002 대한금속·재료학회지 Vol.41 No.2

The characteristics of upper nozzle clogging was investigated using upper nozzle clogging index(CI_Ar) in a continuous casting of steel. CI_Ar was derived from the modified value of argon back pressure, which was dependent on the argon flow rate in upper nozzle, liquid steel throughput, and weight of liquid steel in a tundish. Inclusion attachment to and its dislodging from upper nozzle, the phenomena of which could be detected from the slow increase and the following sudden decrease of CI_Ar, was found to occur continuously for all sequences of cast in case of severe nozzle clogging.

[세션초청논문] Development of the PHM (prognostics and health management) technique for cooling facilities

Jong-Hoon Kang(강종훈) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

Hundreds of thousands of liquid jet nozzles are widely used in controlling cooling equipment to accelerate the cooling of hot plates. The holes of these nozzles become clogged or the hole size becomes smaller as foreign substances like grease, scrap, and mud containing cooling water are flushed through. In this case, cooling water sprays abnormally through the partially clogged or restricted nozzle. This causes inhomogeneous cooling of hot plates. The objective of this study is to develop an evaluation system of cooling headers including nozzles. This paper presents the PHM (prognostics and health management) technique to monitor and evaluate the conditions of spraying nozzles. The sensor module was developed in-house to measure the undulation and clogging of nozzles’ liquid column. In addition, the field test results are also introduced in this paper.

티타늄 첨가강의 연주 노즐막힘 기구

정우광,권오덕,조문규,Jung, Woo-Gwang,Kwon, Oh-Duck,Cho, Mun-Kyu 한국재료학회 2009 한국재료학회지 Vol.19 No.9

In order to provide the mechanism of nozzle clogging, recovered nozzles for high strength steel grade were examined carefully after continuous casting. The thickness of clogged material in SEN is increased in the following order: from the bottom to the top of the nozzle, upper part of slag line, and the pouring hole. Nozzle clogging material begins to form due the adhesion of metal to nozzle wall, the decarburization, and reduction of oxide in the refractory by Al and Ti in the melt. The reduction of oxide in the refractory by Al and Ti improves the wettability of the melt on the refractory and forms a thin Al-Ti-O layer. Metal containing micro alumina inclusions is solidified on the Al-Ti-O layer, and the solid layer grows due to the heat evolution through the nozzle wall. Thermodynamic calculation has been made for the related reactions. The effect of superheat to the nozzle clogging is discussed on ultra low carbon steel and low carbon steel.

Asymmetric nozzle structure for particles converging into a highly confined region

Park, Junha,Chung, Seok,Yun, Hoyoung,Cho, Keunchang,Chung, Chanil,Han, Dong-Chul,Chang, Jun Keun Elsevier 2006 CURRENT APPLIED PHYSICS Vol.6 No.6

<P><B>Abstract</B></P><P>Asymmetric nozzle inlet was suggested for particles to converge into a highly confined region. The physical properties from the nano-scaled volumetric difference at nozzle inlet were investigated using computational fluid dynamics and particle motion measurement with fluorescence beads and erythrocytes. The asymmetric nozzle structure made particles converge efficiently without clogging at nozzle inlet. It could be used as a micro/nanofluidic unit for cell based assay in a microchip such as chip-based flow cytometer.</P>

Observation Evaluation of Nozzle Clogging in a Micro-orifice Impactor Used for Atmospheric Aerosol Sampling

Ji, Jun-Ho,Bae, Gwi-Nam,Hwang, Jungho Taylor Francis 2006 Particulate science and technology Vol.24 No.1

<P>A micro-orifice impactor uses micro-orifice nozzles to extend the cut sizes of the lower stages to as small as 0.18 &mgr;m in diameter without resorting to low pressures or creating excessive pressure drops across the impactor stages. In this work, the phenomenon of nozzle clogging caused by particle deposition was investigated experimentally for a commercial micro-orifice uniform deposit impactor (MOUDI, MSP model 100). Using an optical microscope, we observed that the micro-orifice nozzles of the lower three stages were partially clogged due to particle deposition during the atmospheric aerosol sampling. To examine the effect of nozzle clogging on the performance of the impactor, the pressure drop and the particle collection efficiency were evaluated for the lower three stages. The pressure drops across the clogged nozzles were higher than the nominal values given by the manufacturer. The particle collection efficiency of each stage was evaluated by using an electrical method for fine particles with diameters in the range of 0.1–0.6 &mgr;m. Monodisperse liquid dioctyl sebacate (DOS) particles were used as test aerosols. A Faraday cage was employed to measure the low-level current of the charged particles upstream and downstream of each stage. The collection efficiency curves shifted to correspondence to smaller orifice sizes, and the 50% cutoff sizes were much smaller than those given by the manufacturer for the three stages with nozzles less than 400 &mgr;m in diameter.</P>

Effect of Abnormal Powder Feeding on Mechanical Properties of Fabricated Part in Directed Energy Deposition

Jeongho Yang,Seonghun Ji,Du-Rim Eo,Jong Cheon Yoon,Parviz Kahhal,Hyub Lee,Sang-Hu Park 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.6

Directed energy deposition (DED) is widely employed in the automotive, aerospace, and defense industries for defect repair and remanufacturing. Stable powder feeding through nozzles for the quality of parts is crucial in the DED process. Detecting changes in the powder flow caused by nozzle defects is visually challenging, and identifying defects in additively manufactured components is equally difficult unless significant distortion occurs. Therefore, prior understanding regarding the quality degradation and development mechanism of process defects associated with abnormal powder feeding is necessary, and product defects must be observed. This research focuses on analyzing the effect of nozzle failure on the shape and mechanical properties of parts. Computational fluid dynamics analysis is performed to examine physical phenomena resulting from an abnormal powder supply. Based on the results, an obstructed nozzle causes an abnormal powder supply, thus resulting in defects in additively manufactured components owing to distortions in the melting-pool flow and temperature distribution.

Direct fabrication of copper patterns by reactive inkjet printing

Kim, K.,Ahn, S.I.,Choi, K.C. Elsevier 2013 Current Applied Physics Vol.13 No.9

Reactive inkjet printing (RIP) was applied to fabricate arbitrary copper (Cu) patterns. RIP prints reactive inks which can provide desired materials after the reaction on a substrate. Here, Cu precursors and reducing agents were dissolved together in one solution as a printable ink instead of conventional Cu nanoparticle inks. The prepared reactive ink was applied to the RIP method to provide dot arrays, lines, and films of Cu. The synthesis of Cu was confirmed to occur successfully by thorough analysis. The RIP method can reduce the process cost and resolve critical drawbacks of the conventional inkjet printing such as a nozzle clogging problem. Furthermore, utilizing reactive precursor inks broadens the choice of materials that can be processed by inkjet printing.

Direct fabrication of copper patterns by reactive inkjet printing

김국주,안성일,최경철 한국물리학회 2013 Current Applied Physics Vol.13 No.9

Reactive inkjet printing (RIP) was applied to fabricate arbitrary copper (Cu) patterns. RIP prints reactive inks which can provide desired materials after the reaction on a substrate. Here, Cu precursors and reducing agents were dissolved together in one solution as a printable ink instead of conventional Cu nanoparticle inks. The prepared reactive ink was applied to the RIP method to provide dot arrays, lines,and films of Cu. The synthesis of Cu was confirmed to occur successfully by thorough analysis. The RIP method can reduce the process cost and resolve critical drawbacks of the conventional inkjet printing such as a nozzle clogging problem. Furthermore, utilizing reactive precursor inks broadens the choice of materials that can be processed by inkjet printing.

Morphology and Chemistry of Oxide Inclusions After Al and Ti Complex Deoxidation

선민기,이해건,정인호 대한금속·재료학회 2008 METALS AND MATERIALS International Vol.14 No.6

The morphology and chemistry of oxide inclusions after various Al and Ti complex deoxidation sequences were investigated at 1600℃. Depending on the addition sequence of Al and Ti deoxidants and the holding time, the morphology and the chemistry were changed. In particular, when Ti was added prior to Al, spherical Al₂O₃ oxide inclusions with hollow holes were frequently observed, which is reported for the first time. On the other hand, when Al was added prior to Ti, Al₂O₃ inclusion formed. When Al and Ti were added simultaneously, Al-Ti-O oxide inclusion formed in the beginning and was transformed to Al₂O₃ inclusion. Based on the experimental results, the formation mechanism of the oxide inclusions after Al-Ti deoxidation was proposed. The nozzle clogging of Ti bearing Al killed steel was also discussed based on the experimental results. The morphology and chemistry of oxide inclusions after various Al and Ti complex deoxidation sequences were investigated at 1600℃. Depending on the addition sequence of Al and Ti deoxidants and the holding time, the morphology and the chemistry were changed. In particular, when Ti was added prior to Al, spherical Al₂O₃ oxide inclusions with hollow holes were frequently observed, which is reported for the first time. On the other hand, when Al was added prior to Ti, Al₂O₃ inclusion formed. When Al and Ti were added simultaneously, Al-Ti-O oxide inclusion formed in the beginning and was transformed to Al₂O₃ inclusion. Based on the experimental results, the formation mechanism of the oxide inclusions after Al-Ti deoxidation was proposed. The nozzle clogging of Ti bearing Al killed steel was also discussed based on the experimental results.

Morphology and Chemistry of Oxide Inclusions After Al and Ti Complex Deoxidation

( Min Ki Sun ),( In Ho Jung ),( Hae Geon Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2008 METALS AND MATERIALS International Vol.14 No.6

The morphology and chemistry of oxide inclusions after various Al and Ti complex deoxidation sequences were investigated at 1600℃. Depending on the addition sequence of Al and Ti deoxidants and the holding time, the morphology and the chemistry were changed. In particular, when Ti was added prior to Al, spherical Al2O3 oxide inclusions with hollow holes were frequently observed, which is reported for the first time. On the other hand, when Al was added prior to Ti, Al2O3 inclusion formed. When Al and Ti were added simultaneously, Al-Ti-O oxide inclusion formed in the beginning and was transformed to Al2O3 inclusion. Based on the experimental results, the formation mechanism of the oxide inclusions after Al-Ti deoxidation was proposed. The nozzle clogging of Ti bearing Al killed steel was also discussed based on the experimental results.