• Title, Summary, Keyword: thermal spray Powder

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Synthesis of TiC/Co Composite Powder by the Spray Thermal Conversion of Metallic Salt Solution (금속염용액의 분무열분해에 의한 TiC/Co복합분말 제조)

  • 이길근;문창민;김병기
    • Journal of Korean Powder Metallurgy Institute
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    • v.10 no.4
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    • pp.228-234
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    • 2003
  • In the present study, the focus is on the synthesis of titanium carbide/cobalt composite powder by the spray thermal conversion process using metallic salt solution as the raw materials. Two types of oxide powders of Ti-Co-O system were prepared by the spray drying of two types of metallic salt solutions : titanium chloride-cobalt nitrate and $TiO_2$ powder-cobalt nitrate solutions. These oxide powders were mixed with carbon black, and then these mixtures were carbothermal reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixtures during carbothermal reduction were analysed using XRD and TG-DTA. In the case of using the titanium chloride-cobalt nitrate solution, it could not be obtained TiC/Co composite powder due to contamination of the impurities during the spray drying of the solution. However, in tile case of using the $TiO_2$ powder-cobalt nitrate scullion, TiC-15 wt. %Co composite powder could be synthesized by the spray thermal conversion process. The synthesized TiC-15 wt. %Co composite powder at 120$0^{\circ}C$ for 2 hours has average particle size of 150 nm.

Fabrication of WC-17%Co Composite Powder for Thermal Spray by Spray-Drying Method and HVOF Thermal Spray Characteristics (분무건조법에 의한 용사용 WC-17%Co 복합분말제조 및 HVOF(High Velocity Oxy-Fuel) 용사특성)

  • 설동욱;김병희;임영우;정민석;서동수
    • Journal of Welding and Joining
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    • v.14 no.6
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    • pp.101-108
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    • 1996
  • In this study, WC-l7wt% Co composite powder for thermal spray was fabricated by spray drying method. The agglomerated composite powder had spheroidal morphology and the particle size distribution was 20~60${\mu}{\textrm}{m}$. WC and Co were distributed homogeneously. However, the strength of the spray-dried agglomerate was low due to the pores within the agglomerate. Therefore, the spray-dried agglomerate was broken down during HVOF thermal spray and the microstructure was inhomogeneous with many pores within the coating layer. And the decomposition of WC to W and $W_{6}$ $C_{2.54}$ was accelerated. The strength and flowability of the agglomerate were greatly improved by sintering heat treatment(110$0^{\circ}C$, 1 hour, hi atmosphere), and then the coating layer showed dense and homogeneous microstructure with well-developed splats. The hardness of the coating layer was H $v_{300}$ = 1072.2.2.

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A Study of Gas Dynamics of the High-Velocity Oxy-Fuel Thermal Spray Gun (HVOF 용사총의 기체역학에 관한 연구)

  • Cho, Pil-Jae;Kim, Heuy-Dong
    • Proceedings of the KSME Conference
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    • pp.574-579
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    • 2003
  • The present study addresses an analytical investigation to understand the characteristics of gas flow in the High-Velocity Oxy-Fuel(HVOF) thermal spray gun. One-dimensional analysis is extended to involve the effects of the wall friction and powder particle diameter. From the present analysis it is well known that the flow characteristics inside and outside the thermal spray gun is varied depending on the combustion chamber pressure. The thermal spray gun flow is characterized by six different patterns. The powder particle size and wall friction significantly influence the powder particle velocity. The particle velocity decreases with an increase in the powder particle size. This implies that the combustion chamber pressure should be increased to achieve a higher velocity of the powder particle.

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Fabrication of Mo based Thermal Spray Composite Powder by Self- propagating High- temperature Synthesis (SHS 합성에 의한 몰리브덴계 용사용 복합분말의 제조)

  • Park, Je-Sin;Sim, Geon-Ju
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.763-768
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    • 2001
  • Molybdenum-based thermal spray powder is widely used for coating the moving parts of the internal combustion engines due to its excellent wear resistance. A composite powder of the $Mo_{40}(Al_{1-x}Si_x)_{60}$ system was synthesized using the SHS method. The synthesized bulk was pulverized and specially treated to produce thermal spray powder. It was found that the synthesis reaction consisted of two-steps: the formation of $Al_8/Mo_3$ and the formation of Mo(Al,Si)$_2$. Both the temperature and the rate of the SHS reaction linearly increased with the increase of the value of x in $Mo_{40}(Al_{1-x}Si_x)_{60}$, The temperature and the rate of the reaction were also affected by the compacting density of the specimens, exhibiting the maximum valves at 62% and 60%, respectively. Since spherical shape is advantageous to the thermal spraying process, shape-control of the powder was attempted with PVA as a binding additive, resulting in the successful production of almost perfectly spherical powder of 80 $\mu\textrm{m}$ Ø$(d_{50})$ mean particle size.

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Fabrication and Characteristic of ZrO2-8%Y2O3 Powder for Plasma Spray Coating Manufactured by Mechanical Mixing Method (기계적 혼합에 의한 플라즈마 용사용 ZrO2-Y2O3 분말의 제조 및 특성)

  • Han, Jin-Won;Kwak, Chan-Won;Woo, Kee-Do
    • Korean Journal of Materials Research
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    • v.24 no.7
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    • pp.357-362
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    • 2014
  • Thermal barrier coatings(TBCs) are being applied in many industrial fields such as thermal power generation, aviation and seasonal fields. $ZrO_2-Y_2O_3$(8%) thermal spray coating powders are commercially used as thermal-barrier coating materials to protect against oxidation and corrosion of heat-resistant alloys at elevated temperatures. Currently, $ZrO_2-Y_2O_3$(8%) thermal-spray powder is made using the industrial co-precipitation process, which is very complex and requires a lot of time. In this study, orthorhombic $ZrO_2$ and $Y_2O_3$ powders were fabricated by mechanical mixing, which is more economical than the co-precipitation process. A tetragonal, yttria-stabilized zirconia(YSZ) coating-layer was produced by plasma spraying, using orthorhombic $ZrO_2-Y_2O_3$(8%) powder. Our experimental results indicate that $ZrO_2-Y_2O_3$(8%) mixed powder can be used economically in industry because it is no longer necessary to make this powder by liquid and gas-phase methods.

Microstructural Evolution of Aluminum Nitride - Yttrium Aluminum Garnet Composite Coatings by Plasma Spraying from Different Feedstock Powders (Aluminum Nitride - Yttrium Aluminum Garnet 분말 특성과 플라즈마 용사 코팅층의 미세조직)

  • So, Woong-Sub;Baik, Kyeong-Ho
    • Korean Journal of Materials Research
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    • v.21 no.2
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    • pp.106-110
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    • 2011
  • A high thermal conductive AlN composite coating is attractive in thermal management applications. In this study, AlN-YAG composite coatings were manufactured by atmospheric plasma spraying from two different powders: spray-dried and plasma-treated. The mixture of both AlN and YAG was first mechanically alloyed and then spray-dried to obtain an agglomerated powder. The spray-dried powder was primarily spherical in shape and composed of an agglomerate of primary particles. The decomposition of AlN was pronounced at elevated temperatures due to the porous nature of the spray-dried powder, and was completely eliminated in nitrogen environment. A highly spherical, dense AlN-YAG composite powder was synthesized by plasma alloying and spheroidization (PAS) in an inert gas environment. The AlN-YAG coatings consisted of irregular-shaped, crystalline AlN particles embedded in amorphous YAG phase, indicating solid deposition of AlN and liquid deposition of YAG. The PAS-processed powder produced a lower-porosity and higher-hardness AlN-YAG coating due to a greater degree of melting in the plasma jet, compared to that of the spray-dried powder. The amorphization of the YAG matrix was evidence of melting degree of feedstock powder in flight because a fully molten YAG droplet formed an amorphous phase during splat quenching.

Particle Deposition, PD Process - New Potential in Material Processing -

  • Fukumoto, Masahiro
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.47-48
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    • 2006
  • Oridinal thermal spray process has developed into two ways, namely, temperature dominated represented by plasma spraying, and velocity dominated represented by HVOF. It is common for both that the particle materials sprayed are basically in melted or half melted condition. New process has developed recently, that is, Cold Spray and Aerosol Deposition. Particle's heating is limited in CS lower than half of the material's melting point. Moreover, exactly no heating is loaded in AD process. Through the investigation on common feature for these three spraying processes, potential of new material process - Particle Deposition, PD - is considered and proposed.

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Synthesis of Nanostructured TiC/Co Composite Powder by the Spray Thermal Conversion Process

  • Lee, Gil-Geun;Ha, Gook-Hyun;Kim, Byoung-Kee
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.418-419
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    • 2006
  • In the present, the focus is on the synthesis of nanostructured TiC/Co composite powder by the spray thermal conversion process using titanium dioxide powder has an average particle size of 50 nm and cobalt nitrate as raw materials. The titanium-cobalt-oxygen based oxide powder prepared by the combination of the spray drying and desalting methods. The titanium-cobalt-oxygen based oxide powder carbothermally reduced by the solid carbon. The synthesized TiC-15wt.%Co composite powder at 1473K for 2 hours had an average particle size of 150 nm.

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Preparation of Al-SiCp Composite Coating by Plasma Thermal Spray (플라즈마 용사에 의한 Al-SiCp 복합재료 코팅층의 제조)

  • 민준원;유승을;김영정;김정석;서동수
    • Journal of the Korean Ceramic Society
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    • v.40 no.5
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    • pp.460-467
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    • 2003
  • Al-SiC$_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis.