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대기 플라즈마 용사법으로 제조된 SiCp/Al 복합재료의 열전도도 특성
어광준,강석봉,Gui, Manchang 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.1
Feedstock for plasma spraying was prepared by ball milling with A1-55 vol.%SiC and Al-75 vol.%SiC powder mixtures in different conditions. The average size of SiC particles was varied from 8 to 30 gm. Freestanding SiC_(p)/Al composites were fabricated by atmospheric plasma spraying onto a graphite substrate. Thermal conductivity of the plasma-sprayed composites was measured at room temperature of 25℃ by the laser flash method. Thermal conductivity of the sprayed composites was significantly lower than that of conventionally cast SiCp/Al composites. Thermal conductivity was varied considerably with respect to the SiC size and feedstock preparation method. The deterioration mechanism of thermal conductivity in the sprayed composites was elucidated, and numerical analyses based on theories of Maxwell and thermal boundary resistance were carried out. (Received September 30, 2004)
플라즈마 spray forming법으로 제조된 Al-SiCp 복합재료의 후속공정에 의한 물성 향상
어광준,강석봉 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.3
In order to fabricate aluminum matrix composites reinforced by SiC particulates, atmospheric plasma spray forming method was adopted. Aluminum and SiC powders were mechanically mixed for plasma spraying feedstock. The feedstock was deposited into freestanding bulk composite on a graphite substrate. As-sprayed composites had a great amount of porosity, which reduced thermal properties, especially in thermal conductivity. The spray-formed Al-SiCp composites were rolled at the room and elevated temperature and hot isostatic pressed (HIPped) at 500℃ under 100 MPa. By rolling, the amount of porosity decreased and consequently thermal conductivity increased. Although, the amount of porosity hardly decreased by HIP, thermal conductivity increased due to the precipitation of solid solution elements such as Fe and Si. Coefficients of thermal expansion (CTEs) of the composites were affected less significantly by post treatment.
대기 플라즈마 용사에 의한 Al-SiC 복합재료 판재의 제조에 미치는 공정변수의 영향
어광준,강석봉,양병모 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.6
Increased electronic packaging density requires thermal management materials with high thermal conductivities and low coefficients of thermal expansion (CTEs) matching those of ceramic substrates or semiconductors. Recently, metal matrix composites (MMCs) have been developed, which provide unique combination of properties that make them candidates for thermal management materials. Most of conventional processes to fabricate MMCs have complicated steps that reduce the cost effectiveness, such as the infiltration process requiring a preform preparation and long process time. Plasma spraying can be adopted to produce MMCs in a flexible and cost effective manner. In this study, SiC particles reinforced Al matrix composites were fabricated by atmospheric plasma spraying method. Al and SiC powders were blended and sprayed with plasma arc power. SiC were uniformly dispersed in the Al matrix with a volume fraction of up to 46%. There were also pores in the composite with a range of 1.8∼12 vol.%, which could be tailored by process parameters. The experimental CTEs showed 13.5∼17.6×10^-6/℃ for the Al-SiC composite containing about 40 vol.% SiC, which were matched well with the predicted ones.
어광준,Barton Arkhurst,김일현,김현길,김정한 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.6
This study investigated the feasibility of a direct energy deposition process for fabrication of oxide dispersionstrengthened steel cladding. The effect of the laser working power and scan speed on the microstructural stabilityof oxide nanoparticles in the deposition layer was examined. Y-Ti-O type oxide nanoparticles with a mean diameterof 45 nm were successfully dispersed by the laser deposition process. The laser working power significantlyaffected nanoparticle size and number density. A high laser power with a low scan speed seriously induced particlecoarsening and agglomeration. Compared with bulk oxide dispersion strengthened steel, the hardness of the laserdeposition layer was much lower because of a relatively coarse particle and grain size. Formation mechanism ofnanoparticles during laser deposition was discussed.