• Title/Summary/Keyword: powder composite

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Manufacturing and Properties of CGI-based Composite Coating Layer Utilizing a Warm Spray Process and Cu-Ga and Cu-In Mixed Powders (Warm Spray 공정과 Cu-Ga 및 Cu-In 혼합 분말을 이용한 CGI계 복합 코팅층의 제조 및 특성)

  • Jeon, Min-Gwang;Lee, Myeong-Ju;Kim, Hyeong-Jun;Lee, Kee-Ahn
    • Journal of Powder Materials
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    • v.21 no.3
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    • pp.229-234
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    • 2014
  • This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and a mixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, the Cu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of $35.4{\mu}m$. Through the utilization of a warm spray process, a CIG-based composite coating layer of $180{\mu}m$ thickness could be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layer underwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, an annealing heat treatment was conducted at temperatures of $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ for 1 hour each. The microstructure analysis identified ${\alpha}$-Cu, $Cu_4In$ and $Cu_3Ga$ phases in the early mixed powder, while $Cu_4In$ disappeared, and additional $Cu_9In_4$ and $Cu_9Ga_4$ phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatment reduced from 0.75% (warm sprayed coating layer) to 0.6% (after $600^{\circ}C/1hr$. heat treatment), and hardness reduced from 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.

Tribological Properties of Reaction-Bonded SiC/Graphite Composite According to Particle Size of Graphite (반응소결 SiC/Graphite 복합체에서 Graphite 입자의 크기에 따른 마찰마모특성)

  • Baik, Yong-Hyuck;Seo, Young-Hean;Choi, Woong;Lee, Jong-Ho
    • Journal of the Korean Ceramic Society
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    • v.34 no.8
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    • pp.854-860
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    • 1997
  • The tribological property of ceramics is very important for use in seal rings, pump parts, thread guides and mechanical seal, etc. In the present study, which RBSC/graphite composites were manufactured by adding graphite powders with different particle sizes to mixtures of SiC powder, metallic silicon, carbon black and alumina, effects on the tribological property of each RBSC/graphite composite was investigated in accordance with the particle size of the added graphite powder. The water absorption, the bending strength and the resistance for the friction and wear were measured, and the crystalline phase and the microstructure were respectively examined by using XRD and SEM. In case that the particle size of the graphite powder was fine(2${\mu}{\textrm}{m}$), the formation of $\beta$-SiC was accelerated, thereby making the increase of the bending strength and the decrease of the water absorption, but no improvement for the tribological properties. Furthermore, in case that the particle size of the graphite powder was some large(88~149${\mu}{\textrm}{m}$), the formation of $\beta$-SiC was not accelerated, to thereby make the decrease of the bending strength and the increase of the water absorption, but the improvement for the tribological property of only the composite having the graphite powder of 20 vol%. In addition, in case that the particle size distribution of the graphite powder was large (under 53 ${\mu}{\textrm}{m}$), there was no improvement for every properties. However, the composites, which the graphite powder with the particle size of 53~88 ${\mu}{\textrm}{m}$ was added in 10~15 vol%, had the most increased resistance for the friction and wear which show the worn out amount of 0.4~0.6$\times$10-3 $\textrm{cm}^2$, and the value of the bending strength is 380~520 kg/$\textrm{cm}^2$.

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The Effects of Kaolin Addition on the Properties of Reticulated Porous Diatomite-kaolin Composites (고령토의 첨가가 3차원 망상 구조를 가지는 다공성 규조토-고령토 복합재의 기본 특성에 미치는 영향)

  • Lee, Chae-Young;Lee, Sujin;Ha, Jang-Hoon;Lee, Jongman;Song, In-Hyuck;Moon, Kyoung-Seok
    • Journal of Powder Materials
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    • v.27 no.4
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    • pp.325-332
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    • 2020
  • In this study, the effects of kaolin addition on the properties of reticulated porous diatomite-kaolin composites are investigated. A reticulated porous diatomite-kaolin composite is prepared using the replica template method. The microstructure and pore characteristics of the reticulated porous diatomite-kaolin composites are analyzed by controlling the PPI value (45, 60, and 80 PPI) of the polyurethane foam (which are used as the polymer template), the ball-milling time (8 and 24 h), and the amount of kaolin (0-50 wt. %). The average pore size decreases as the amount of kaolin increases in the reticulated porous diatomite-kaolin composite. As the amount of kaolin increases, it can be determined that the amount of inter-connected pore channels is reduced because the plate-shaped kaolin particles connect the gaps between irregular diatomite particles. Consequently, a higher kaolin percentage affects the overall mechanical properties by improving the pore channel connectivity. The effect of kaolin addition on the basic properties of the reticulated porous diatomite-kaolin composite is further discussed with characterization data such as pore size distribution, scanning electron microscopy images, and compressive strength.

Preparation of SiC-Al alloy Composite by Pressureless Powder Packing Forming Method (분말 충전 성형법을 이용한 SiC-Al Alloy 복합체의 제조)

  • 박정현;송준광;백승수;염강섭;강민수
    • Journal of the Korean Ceramic Society
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    • v.34 no.4
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    • pp.343-350
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    • 1997
  • To fabricate the ceramic/metal(SiC/ Al alloy) composite, SiC preform was prepared by Pressureless Powder Packing Forming Method and 6061 Al alloy was infiltrated into the preform. Uniform compact having an average pore size of 10 ${\mu}{\textrm}{m}$ and narrow pore size distribution was prepared. Phenolic resin solution(40 wt%) was penetrated into the SiC compact, and then the compact was preheated at the temperature of 120$0^{\circ}C$. The pore size distribution and the microstructure of the preform were not changed by preheating. An uniform microstructure without any crack in the preform was obtained in SiC-Al alloy composite. The infiltration of 6061. Al alloy into the preform began at the temperature of 130$0^{\circ}C$ and the amount of infiltration increased in proportion to the infiltration temperature and the soaking time. The increasement rate of the infiltration amount decreased after 3 h. As a result of the infiltration at 140$0^{\circ}C$ for 4 h, Al alloy was well distributed in the interparticle channels and the relative density of the composite was above 98%. The strength and the fracture toughness of the composite were 303 MPa and 21.65 MPam1/2, respectively.

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Experimental Study on Improving Compressive Strength of Hexagonal Boron Nitride Reinforced Cement Composite (Hexagonal-Boron Nitride 강화 시멘트 복합체의 압축강도 향상에 대한 실험적 연구)

  • Choi, Yomin;Shin, Hyun-Gyoo
    • Journal of Powder Materials
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    • v.27 no.6
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    • pp.503-508
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    • 2020
  • The mechanical properties and microstructures of hexagonal boron nitride (h-BN)-reinforced cement composites are experimentally studied for three and seven curing days. Various sizes (5, 10, and 18 ㎛) and concentrations (0.1%, 0.25%, 0.5%, and 1.0%) of h-BN are dispersed by the tip ultrasonication method in water and incorporated into the cement composite. The compressive strength of the h-BN reinforced cements increases by 40.9%, when 0.5 wt% of 18 ㎛-sized h-BN is added. However, the compressive strength decreases when the 1.0 wt% cement composite is added, owing to the aggregation of the h-BNs in the cement composite. The microstructural characterization of the h-BN-reinforced cement composite indicates that the h-BNs act as bridges connecting the cracks, resulting in improved mechanical properties for the reinforced cement composite.

Development of Carbon Nanotubes and Polymer Composites Therefrom

  • Jain, P.K.;Mahajan, Y.R.;Sundararajan, G.;Okotrub, A.V.;Yudanov, N.F.;Romanenko, A.I.
    • Carbon letters
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    • v.3 no.3
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    • pp.142-145
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    • 2002
  • Multiwall carbon nanotubes (MWNT) were produced using the arc-discharge graphite evaporation technique. Composite films were developed using MWNT dispersed in polystirol polymer. In the present work, various properties of the polymeric thin film containing carbon nanotubes were investigated by optical absorption, electrical resistivity and the same have been discussed.

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Strength of Crack Healed-Specimen and Elastic Wave Characteristics of Al2O3/SiC Composite Ceramics (알루미나 탄화규소 복합세라믹스 균열치유재의 강도와 탄성파 특성)

  • Kim, Hae-Suk;Kim, Mi-Gyeong;Kim, Jin-Uk;An, Seok-Hwan;Nam, Gi-U
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.4
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    • pp.425-431
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    • 2007
  • [ $Al_2O_3/SiC$ ]composite ceramics were sintered to evaluate the bending strength and elastic wave characteristics. The three-point bending test was carried out under room temperature. The elastic wave was detected by fracture wave detector. The crack healing behavior was investigated from 1373 K to 1723 K. The bending strength of $Al_2O_3/SiC$ composite by nanocomposite is higher than that of $Al_2O_3$ monolithic. Crack-healing behavior depended on an amount of additive powder $Y_2O_3$. In $Al_2O_3/SiC$ composite ceramics with 3 wt. % $Y_2O_3$ for additive powder, the bending strength at 1573 K is about 100% increase than that of the smooth specimens. From the result of wavelet analysis of elastic wave signal, the smooth specimen and heat treated specimen of $Al_2O_3$ monolithic and $Al_2O_3/SiC$ composite ceramics showed characteristics of frequency about 58 kHz. The strength of $Al_2O_3/SiC$ composite ceramics was a little higher than those of $Al_2O_3$ monolithic. The dominant frequencies were high with increasing of $Y_2O_3$ for additive powder. The dominant frequencies had direct connection with the bending strength.

Microstructure and Hardness of TiC Particle-reinforced Fe Self-fluxing Alloy Powders Based Hybrid Composite Prepared by High Energy Ball Milling

  • Park, Sung-Jin;Song, Yo-Seung;Nam, Ki-Seok;Chang, Si-Young
    • Journal of Powder Materials
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    • v.19 no.2
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    • pp.122-126
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    • 2012
  • The Fe-based self-fluxing alloy powders and TiC particles were ball-milled and subsequently compacted and sintered at various temperatures, resulting in the TiC particle-reinforced Fe self-fluxing alloy hybrid composite, and the microstructure and micro-hardness were investigated. The initial Fe-based self-fluxing alloy powders and TiC particles showed the spherical shape with a mean size of approximately 80 ${\mu}m$ and the irregular shape of less than 5 ${\mu}m$, respectively. After ball-milling at 800 rpm for 5 h, the powder mixture of Fe-based self-fluxing alloy powders and TiC particles formed into the agglomerated powders with the size of approximately 10 ${\mu}m$ that was composed of the nanosized TiC particles and nano-sized alloy particles. The TiC particle-reinforced Fe-based self-fluxing alloy hybrid composite sintered at 1173 K revealed a much denser microstructure and higher micro-hardness than that sintered at 1073 K and 1273 K.

A Study on $CeO_2/SiO_2$ Composite Powder Synthesis Using Ultrasonic Spray Pyrolysis Method and Effect of Sensory Texture Improvement

  • Lee, Dong-Kyu;Lee, Jin-Hwa
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.2
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    • pp.175-181
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    • 2005
  • The spherical particles of $CeO_2/SiO_2$ composite powder with narrow-size distribution and pure phase particles were synthesized by ultrasonic spray pyrolysis method from aqueous cerium sulfate solution. The resulting composite powder was characterized by X-ray diffraction, scanning electron microscopy, transmittance electron microscopy, in-vitro sun protect factor, and BET surface area analysis. The concentration of cerium sulfate was tested to vary the particle size from $3.40{\times}10^{-3}$ to $1.02{\times}10^{-2}mol/cm^3$ to study concentration effect of starting material. The average particle size from the $3.40{\times}10^{-3}mol/cm^3$ concentration was found to be slightly smaller than that from the $1.02{\times}10^{-2}mol/cm^3$ concentration, because of the relation between the droplet size and the concentration of the starting material solution.

Effect of Modification PP on the Physical Properties and CNF Dispersion of PP Powder/CNF 1 wt% Slurry Composite (PP 분말/CNF 1 wt% 슬러리 복합체의 CNF 분산 및 물성에 대한 개질 PP의 영향)

  • Kim, Jun Seok;Kim, Youn Cheol
    • Applied Chemistry for Engineering
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    • v.33 no.3
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    • pp.284-288
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    • 2022
  • Polypropylene (PP) powder/cellulose nanofibers (CNF) 1 wt% slurry composites were prepared by filtering their suspension under reduced pressure and dried them in an oven followed by the use of a twin screw extruder. PP modified with side branches and polar groups was used. The side branches and polar groups were introduced into PP by using divinylbenzene and maleic anhydride (MAH), respectively. As a result of examining the dispersibility of CNF and the physical properties of the composite, it was confirmed that the composite prepared from PP powder/CNF 1 wt% slurry showed equal or higher levels in tensile and flexural strength as compared with those using the composite prepared from CNF powder.