Fumio Ogawa 교수

The compatibility of carbon nanofibers (CNFs) with aluminum is important for the fabrication of CNF-reinforced aluminum matrix composites with superior mechanical and thermal properties. In this study, aluminum was deposited on CNFs by in situ chemical vapor deposition (CVD) utilizing I2 for the transportation of aluminum atoms. The microstructure of the aluminum-coated CNFs and the crystal structure of the aluminum coating layers were studied. When aluminum powder with ∼3 μm diameter particles,

The van der Waals agglomeration of carbon nanofibers (CNFs) and the weight difference and poor wettability between CNFs and aluminum hinder the fabrication of dense CNF-reinforced aluminum matrix composites with superior properties. In this study, to improve this situation, CNFs were coated with aluminum by a simple and low-cost in situ chemical vapor deposition (in situ CVD). Iodine was used to accelerate the transport of aluminum atoms. The coating layer formed by the in situ CVD was character

A new fatigue-testing machine was developed to perform high-cycle multiaxial fatigue tests at 50 Hz, in order to reduce testing time. The developed machine can combine bending and torsion loading and perform fatigue tests at a high frequency, under proportional and non-proportional loading conditions, where the principal stress direction changes during a cycle. The proportional loading is cyclic bending loading, and the non-proportional loading is cyclic, combining bending and reversed torsion l

In-situ chemical vapor deposition (CVD) of aluminum on vapor grown carbon fibers (VGCF) was investigated for the fabrication of Al-VGCF composites. Reaction of aluminum powder with iodine was used to produce the aluminum vapor source. Aluminum powder, VGCF and iodine powder were placed into quartz tubes in various molar ratios and the quartz tubes were sealed in vacuum. Then they were annealed in the furnace. Annealing temperature was 673K or 773K. Obained powder was observed using a field emiss

This paper presents the characterization of nonlinear viscoelastic behavior in vinylester resin. The description of nonlinear viscoelastic behavior is based on well-known Schapery's constitutive equation. Cardon proposed the method that can estimate nonlinear parameters in Schapery's constitutive equation, separately by creep-recovery tests in consideration of permanent deformation nonexistent in original Schapery's constitutive equation. However, formulation of permanent deformation has almost

In this study, creep properties of lead-free solders based on Sn1.0Ag0.7Cu were investigated. In the solders, germanium, nickel and bismuth were added to improve their mechanical properties. The effect of element addition on their microstructure and creep properties were studied. Creep properties were improved with the element addition. Creep rupture lifetime was the longest for SnAgCuBiNiGe, and that of SnAgCuBi was the second longest. It was made clear that a minimum creep strain rate is usefu

Aluminum matrix composites reinforced by vapor grown carbon fibers (VGCF) were fabricated by powder can extrusion. Extrusion ratio was 9 or 16. Temperature and heating duration were changed to investigate the effect of extrusion condition on properties of composites. Measurement of micro-Vickers hardness, tensile strength was conducted and microstructure such as VGCF orientation was characterized. When extrusion temperature was higher or when heating duration was longer, mechanical strength was

In this study, we investigated the effect of reinforcement sizes on the tensile strength and ductility of carbon nanotube (CNT)-reinforced aluminum matrix composites fabricated through ball milling, followed by hot extrusion of a powder encapsulated in an aluminum container. We analyzed the microstructural properties of the samples, including the aluminum grain size, its spatial variation with the alignment of CNT, and CNT length. Nanoindentation test results revealed the spatial variation of ha

The balance of tensile strength and failure strain of cellulose material is important for their use in food packages, drink bottles, electronic packages, and automobiles. The microstructures, tensile properties, and fracture surfaces of two cellulose nanofiber films were examined. The films were treated with phosphate ester and heated. The first film (#21129–1) was made from conifer wood pulps, its average tensile strength was 64.6 MPa and failure strain was 5.5 %. This film presented a constant