ORAL

SESSION: CompositeWedAM-R9	5th Intl. Symp. on Composite, Ceramic and Nano Materials Processing, Characterization and Applications
Wed Oct, 25 2017	Room: Condesa III
Session Chairs: Fumio Ogawa; Kamlesh Phapale; Session Monitor: TBA

12:00: [CompositeWedAM03]
Carbon Nanotube-Reinforced Aluminum Matrix Composites Fabricated by Hot Extrusion of Ball-milled Powders Encapsulated in Aluminum Containers
Fumio Ogawa¹ ; Chitoshi Masuda² ; ¹Ritsumeikan University, Kusatsu, Japan; ²Kagami Memorial Institute for Materials Science and Technology, Waseda University, Shinjuku-ku, Japan;
Paper Id: 229 [Abstract]

Carbon nanotubes (CNTs) and aluminum powder were mixed using ball-milling. Two types of CNTs were adopted; one is vapor grown carbon fibers (VGCFs) with average diameter of 150 nm, while the other is multi-walled carbon nanotubes (MWCNTs) with average diameter of 65 nm. Mixing of CNTs with aluminum powder was performed at rotation speed of 200 rpm and mixing duration was 3 h. The weight fraction of stainless-steel balls to the mixture of CNT and aluminum powder was 20:1. The mixed powders were encapsulated in the A1050 containers in vacuum of 10-5 Torr. Then, the container was served as an extrusion billet. Hot extrusion was performed at 550 oC with extrusion ratio of 9. Composites reinforced by above mentioned two types of CNTs were fabricated using the same condition. Mechanical and thermal properties of composites were evaluated. Vickers microhardness of both of composites was higher than 100HV, and it increased with reinforcement volume fraction. That of MWCNT-reinforced composites was higher than that of VGCF-reinforced composites. Tensile strength of MWCNT-reinforced composites was also higher than that of VGCF-reinforced composites and was over 450 MPa. Fracture strain of 0.5% MWCNT-reinforced composite was 37.2% that was the highest among the values reported in the literature. Thermal conductivity of VGCF-reinforced composites was higher than that of MWCNT-reinforced composites. That of 0.5% VGCF-reinforced composites was 203.7 W/mK. Composites with tensile strength, fracture strain and thermal conductivity that are high compared to the values reported in past could be fabricated via simple process except for minimizing CNTs damage during mixing and by prevention of oxidation and excessive reaction of CNTs with aluminum matrix retaining effective densification during hot extrusion.

SESSION: CompositeWedAM-R9	5th Intl. Symp. on Composite, Ceramic and Nano Materials Processing, Characterization and Applications
Wed Oct, 25 2017	Room: Condesa III
Session Chairs: Fumio Ogawa; Kamlesh Phapale; Session Monitor: TBA

15:00: [CompositeWedAM06]
Deposition of Metals on Vapor Grown Carbon Fibers via in-situ Chemical Vapor Deposition and Fabrication of Metal Matrix Composites Utilizing Coated Fibers
Fumio Ogawa¹ ; Chitoshi Masuda² ; Hidetoshi Fujii³ ; ¹Ritsumeikan University, Kusatsu, Japan; ²Kagami Memorial Institute for Materials Science and Technology, Waseda University, Shinjuku-ku, Japan; ³Joining and Welding Research Institute, Osaka University, Ibaraki, Japan;
Paper Id: 238 [Abstract]

Aluminum, nickel, silicon and titanium were deposited on the surface of vapor grown carbon fibers (VGCFs) via simple and cost effective in situ chemical vapor deposition (in situ CVD) utilizing iodine to transport metallic atoms. For aluminum coating, coating layer was formed by annealing at 500oC. It was confirmed that metallic aluminum layers were almost homogeneously formed on VGCFs. Aluminum matrix composites reinforced by aluminum-coated VGCFs were fabricated via powder metallurgy (PM). Tensile strength of aluminum matrix composites was improved by coating treatment. For nickel coating, coating layer was formed by annealing at 600oC. It was found that metallic nickel coating that consisted of grains with the size of ~5 nm was formed. The wettability of sheets consisting of nickel-coated VGCFs by molten aluminum was investigated. It was apparent that the wettability was improved by the coating treatment. Aluminum matrix composites containing nickel-coated VGCFs were fabricated via hot extrusion of mixed powder of Al-7Si and VGCFs at semi-solid temperature. It was found that Vickers microhardness values were improved owing to nickel coating treatment of VGCFs because of improved interaction of aluminum matrix and VGCFs at the interface. For silicon coating, coating layer was formed by annealing at 1100oC. Coating layer consisted of metallic silicon, although the surface of the coating layer was oxidized. For titanium coating, reaction of VGCFs with titanium and conversion of VGCF surface into titanium carbide (TiC) was confirmed. It was also found that the extent of reaction could be varied by the amount of iodine, annealing temperature and annealing duration.