• Title/Summary/Keyword: Al Powder spray

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Relationship between Particle Density and Electrochemical Properties of Spherical LiMn2-xMxO4 (M = Al, Mg, B) Spinel Cathode Materials (구형 스피넬계 LiMxMn2-xO4 (M = Al, Mg, B) 양극소재의 입자치밀도와 전지성능간의 상관관계에 대한 연구)

  • Kim, Kyoung-Hee;Jung, Tae-Gyu;Song, Jun-Ho;Kim, Young-Jun
    • Journal of the Korean Electrochemical Society
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    • v.15 no.2
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    • pp.67-73
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    • 2012
  • Spherical lithium manganese oxide spinel, $LiMn_{2-x}M_xO_4$ (M = Al, Mg, B) prepared by wet-milling, spray-drying, and sintering process has been investigated as a cathode material for lithium ion batteries. As-prepared powders exhibit various surface morphologies and internal density in terms of boron (B) doping level. It is found that the dopant B drives the growth of the primary particle and minimizes the surface area of the powder. As a result, the dopant enhances the internal density of the particles. Electrochemical tests demonstrated that the capacity of the synthesized material at 5 C could be maintained up to 90% of that at 0.2 C. The cycle performance of the material showed that the initial capacity was retained up to 80% even after 500 cycles under the high temperature of $60^{\circ}C$.

Friction, Wear and Adhesion of HVOF Coating of Co-alloy Powder

  • Cho, Tong-Yul;Yoon, Jae-Hong;Song, Ki-Oh;Joo, Yun-Kon;Fang, Wei;Zhang, Shihong;Youn, Suk-Jo;Chun, Hui-Gon;Hwang, Soon-Young
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2007.11a
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    • pp.61-62
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    • 2007
  • HVOF thermal spray coating of micron size Co-alloy powder has been studied for the durability improvement of high velocity spindle (HVS). Optimal coating process of this system for the best surface properties is hydrogen flow rate 75 FMR, oxygen flow rate 38-42 FMR, feed rate 30 g/min at spray distance 5 inch. Friction coefficient (FC) and wear trace (WT) decrease increasing coating surface temperature from 25$^{\circ}$C to 538$^{\circ}$C due to the higher lubricant effects of the oxides at the higher temperature. At the study of adhesion of T800 coating on a light metal alloy Ti-6Al-4V (Ti64) tensile bond strength (TBS) and tensile fracture location (TFL) of Ti64/T800 are 8,740 psi and near middle of T800 coating respectively. This shows that adhesion of Ti64/T800 is higher than the cohesion strength (8,740 psi) of T800 coating. Therefore T800 coating is strongly advisable for the surface coating on HVS such as high speed air-bearing spindle.

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Solid-state synthesis of yttrium oxyfluoride powders and their application to plasma spray coating (옥시불화이트륨 분말의 고상합성 및 플라즈마 스프레이 코팅 적용)

  • Lee, Jung-Il;Kim, Young-Ju;Chae, Hui Ra;Kim, Yun Jeong;Park, Seong Ju;Sin, Gyoung Seon;Ha, Tae Bin;Kim, Ji Hyeon;Jeong, Gu Hun;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.31 no.6
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    • pp.276-281
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    • 2021
  • In order to manufacture a semiconductor circuit, etching, cleaning, and deposition processes are repeated. During these processes, the inside of the processing chamber is exposed to corrosive plasma. Therefore, the coating of the inner wall of the semiconductor equipment with a plasma-resistant material has been attempted to minimize the etching of the coating and particle contaminant generation. In this study, we synthesized yttrium oxyfluoride (YOF) powder by a solid-state reaction using Y2O3 and YF3 as raw materials. Mixing ratio of the Y2O3 and YF3 was varied from 1.0:1.0 to 1.0:1.6. Effects of the mixing ratio on crystal structure and microstructure of the synthesized YOF powder were investigated using XRD and FE-SEM. The synthesized YOF powder was successfully applied to plasma spray coating process on Al substrate.

Optimization of powder compaction parameters for the pressureless sintered ZTA (상압소결 ZTA의 분말 성형 공정 최적화)

  • 신동우;김경도;박삼식;임창성;이수완
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.356-364
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    • 1998
  • The dependence of green and sintered densities of Zirconia-Toughened Alumina ($ZTA:\;Al_2O_3/\;15\;vol{%}\;ZrO_2$) on the properties of spray-dried granules was studied thoroughly to establish the optimum compaction condition leading to high reproducibility in the light of sintered density. The sphericity, mean size, degree of hollow occurrence and moisture content of spray-dried granules were largely different in between the granule containing binder and the ones with no binder. The effect of these differences in the characteristic of granules on the compaction behavior was examined in terms of the compaction pressure from 80 MPa to 120 MPa 10 MPa increment and the compaction method, i.e., uniaxial and cold isostatic pressing. This work confirmed that the reproducibility of sintered density caused by the variation of granule property could be improved by the optimization of compaction process. The variation of sintered density was controlled within 1 % deviation by compacting the granules under a relatively low pressure of 80 MPa in an uniaxial forming and subsequent cold isostatic pressing at high pressure of 500 MPa.

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Polishing Characteristics and Development of Automatic Die Polishing Machine by Liquid Honing (액체호닝에 의한 금형 자동 사상기계개발 및 가공 특성)

  • 김재도;류기덕;홍정석
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.6
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    • pp.162-168
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    • 2000
  • The automatic die polishing machine by liquid honing has been developed and experimented on the surface of machined die. The goal of development in the automatic die polishing machine by liquid honing is to increase the accuracy and the productivity in die polishing. To reach this goal, the polishing machine consists of the automatic measuring device for contour of die, the nozzle and pumping system to spray the powder mixed with liquid, and the 3-axis guides. Before polishing, the measuring device with a semiconductor laser scans the surface of mould to get the data of contour. The data store a PC and use to control the nozzle head to move above a couple of centimeters on the machined surface of die. The experimental parameters are the spraying time, the pressure, the size of abrasive grain and the mixing ratio between abrasive grain and liquid. The surface roughness is measured on the polished die which are SKDl 1 and Al7075 machined by NC. The surface roughness indicates the values of Rmax 0.5${\mu}{\textrm}{m}$ for Al7075 and Rmax 1.4${\mu}{\textrm}{m}$ for SKDl 1. It reduces the polishing time significantly and reduces the monotonous work for labors. As the results, the liquid honing system is useful method to apply for the die polishing and the automatic die polishing machine using liquid honing shows that it's very effective processing ability.

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Thermal Durability of 4YSZ Thermal Barrier Coating Deposited by Electron Beam PVD (전자빔을 이용한 물리기상증착법으로 제조된 열차폐용 4 mol% YSZ 코팅의 내열특성)

  • Park, Chanyoung;Yang, Younghwan;Kim, Seongwon;Lee, Sungmin;Kim, Hyungtae;Lim, Daesoon;Jang, Byungkoog;Oh, Yoonsuk
    • Journal of Powder Materials
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    • v.20 no.6
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    • pp.460-466
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    • 2013
  • 4 mol% Yttria-stabilized zirconia (4YSZ) coatings with $200{\mu}m$ thick are fabricated by Electron Beam Physical Vapor Deposition (EB-PVD) for thermal barrier coating (TBC). $150{\mu}m$ of NiCrAlY based bond coat is prepared by conventional APS (Air Plasma Spray) method on the NiCrCoAl alloy substrate before deposition of top coating. 4 mol% YSZ top coating shows typical tetragonal phase and columnar structure due to vapor phase deposition process. The adhesion strength of coating is measured about 40 MPa. There is no delamination or cracking of coatings after thermal cyclic fatigue and shock test at $850^{\circ}C$.

Effect of processing parameters on TiO2 film by room temperature granule spray in vacuum (상온진공과립분사에 의한 TiO2 코팅층에 미치는 공정변수의 영향)

  • Kim, Han-Gil;Park, Yoon-Soo;Bang, Kook-Soo;Park, Dong-Soo;Park, Chan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.27 no.1
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    • pp.22-27
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    • 2017
  • $TiO_2$ films, thickness of $1{\sim}30{\mu}m$ were deposited on glass substrate at room temperature by room temperature granule spray in vacuum. The starting powder was calcinated at $600^{\circ}C$ for 4 h using $Al_2O_3$ crucible in the furnace. The particle size of the $TiO_2$, $1.5{\mu}m$ was measured by a particle size analyzer. The effect of different process parameters such as number of pass, gas flow rate and feeder voltage was studied. As the number of passes increased, the film thickness increased proportionally due to adequate kinetic energy conserved. The effect of three different flow rates (i.e. 15, 25, and 35 LPM) on deposited film was investigated. As gas flow rate increased, the film thickness increased up to 25 LPM and then decreased. Higher feeder voltage with low flow rate of 15 LPM resulted in unsufficient coating thickness due to insufficient kinetic energy. Microstructure of $TiO_2$ films was investigated by scanning electron microscope and high resolution tramission electron microscope.

Studies on Packaging of Spray-dried Soy Sauce by Means of Flexible Films and Their Laminates (유연(柔軟) 포장재료(包裝材料)를 이용(利用)한 분말(粉末) 간장의 포장(包裝)에 관(關)한 연구(硏究))

  • Chang, K.S.;Yoon, H.K.;Kim, M.S.
    • Applied Biological Chemistry
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    • v.21 no.3
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    • pp.144-149
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    • 1978
  • Fermented soy sauce was dehydrated by spray drying to form powder, and moisture sorption properties of powdered soy sauce with or without cover of the flexible films were examined on different relative humidity by using saturated salt solutions at $30^{\circ}$. The results obtained were summarized as follows: The equilibrium moisture content of spray-dried soy sauce containing 18.3% moisture was determined to 52% by graphical interpolation method, and E.M.C. of powdered soy sauce covered with plastic films decreased at low relative humidity whereas sharply increased curves were seen at high relative humidity. The rate constant of moisture adsortion K for the power covered with films were $66.2{\times}10^{-5}\;to\;225{\times}10^{-5}/hr$., and K' became greater when film having higher water vapor transmission rate was used. The shelf-life of powdered soy sauce covered with Al. foil/P.E. film by Brown formula at the accelerated condition of $38^{\circ}$, 92% R. H. was the longest period, 164 days compared with any other films used, and the shortest period, 18 days in P.V.C. film.

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Improvement of Adhesion Strength of High Temperature Plasma Coated Aluminum Substrate with Aluminum-Alumina Powder Mixture (알루미늄 기지에 알루미늄-알루미나 혼합분말을 이용한 고온플라즈마 열분사 코팅층의 밀착강도 향상기구)

  • Park, Jin Soo;Lee, Hyo Ryong;Lee, Beom Ho;Park, Joon Sik
    • Korean Journal of Materials Research
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    • v.25 no.5
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    • pp.226-232
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    • 2015
  • High temperature plasma coating technology has been applied to recover damaged aluminum dies from wear by spraying pure aluminum and alumina powder. However, the coated mixed powder layer composed of aluminum and alumina often undergoes a detachment from the substrate, making the coated substrate die unable to maintain its expected life span. In this study, in order to increase the bonding strength between the substrate and the coating layer, a pure aluminum layer was applied as an intermediate bond layer. In order to prepare the specimen with variable bond coating conditions, the bond coat layers with a various gun speed from 10 cm/sec to 30 cm/sec were prepared with coating cycle variations ranging from three to nine cycles. The specimen with a bond coat layer coated with a gun speed of 20 cm/sec and three coating cycles exhibited ~13MPa of adhesion strength, while the specimen without a bond coat layer showed ~6 MPa of adhesion strength. The adhesion strength with a variation of bond coat layer thickness is discussed in terms of coating parameters.

Phtocatalytic Activity of the $SrBi_2Nb_2O_9$ Thick Film by Aerosol Deposition (Aerosol deposition을 이용한 $SrBi_2Nb_2O_9$의 고정화에 의한 광촉매 특성에 관한 연구)

  • Kim, Ji-Ho;Choi, Duck-Kyun;Hwang, Kwang-Taek;Ko, Sang-Min;Cho, Woo-Seok;Kim, Jin-Ho
    • Journal of Hydrogen and New Energy
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    • v.21 no.5
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    • pp.375-382
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    • 2010
  • A layered perovskite photocatalysts, $SrBi_2Nb_2O_9$ (SBN), was synthesized by the conventional solid-state reaction method and characterized by X-ray diffraction (XRD) and UV-visble spectrophotometry. The results showed that the structure of $SrBi_2Nb_2O_9$ is orthorhombic. Diffuse reflectance spectra for calcined and attrition-milled SBN showed the main absorption edges were less 400 nm, that is ultraviolet region. SBN under micron-sized powder was deposited on the $Al_2O_3$ by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $SrBi_2Nb_2O_9$ photocatalytic thick film was fabricated. AD-deposited SBN thick films were characterized by XRD, scanning electron microscopy (SEM) and UV-visable spectrophotometry, Moreover, it was found that several nano-sized SBN film by AD process can improve the photocatalytic activity under visable reflectance.