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RISS 인기검색어
- 검색키워드
- 저자 : T. Ogasawara (검색결과 7 건)
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Effect of HTT on Bending and Tensile Properties of 2D C/C Composites
S.R. Dhakate,T. Aoki,T. Ogasawara 한국탄소학회 2005 Carbon Letters Vol.6 No.4
Bending and tensile properties of 2D cross-ply C/C composites with processing heat treatment temperature (HTT) are evaluated. C/C composites used are made from two types of PAN based T700 and M40 carbon fibers with phenolic resin as carbon matrix precursor. Both the types of composites are heat treated at different temperatures (ranging from 750 to 2800℃) and characterized for bending and tensile properties. It is observed that, real density and open porosity increases with HTT, however, bulk density does show remarkable change. The real density and open porosity are higher in case T-700 carbon fiber composites at 2800℃, even though the density of M40 carbon fiber is higher. Bending strength is considerably greater than tensile strength through out the processing HTT due to the different mode of fracture. The bending and tensile strength decreases in both composites on 1000℃ which attributed to decrease in bulk density, thereafter with increase in HTT, bending and tensile strength increases. The maximum strength is in T700 fiber based composites at HTT 1500℃ and in M40 fiber based composites at HTT 2500℃. After attending the maximum value of strength in both types of composite at deflection HTT, after that strength decreases continuously. Decrease in strength is due to the degradation of fiber properties and in-situ fiber damages in the composite. The maximum carbon fiber strength realization in C/C composites is possible at a temperature that is same of fiber HTT. It has been found first time that the bending strength more or less 1.55 times higher in T700 fiber composites and in M40 fiber composites bending strength is 1.2 times higher than that of tensile strength of C/C composites.
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Effect of HTT on Bending and Tensile Properties of 2D C/C Composites
Dhakate, S.R.,Aoki, T.,Ogasawara, T. Korean Carbon Society 2005 Carbon Letters Vol.6 No.4
Bending and tensile properties of 2D cross-ply C/C composites with processing heat treatment temperature (HTT) are evaluated. C/C composites used are made from two types of PAN based T700 and M40 carbon fibers with phenolic resin as carbon matrix precursor. Both the types of composites are heat treated at different temperatures (ranging from 750 to $2800^{\circ}C$) and characterized for bending and tensile properties. It is observed that, real density and open porosity increases with HTT, however, bulk density does show remarkable change. The real density and open porosity are higher in case T-700 carbon fiber composites at $2800^{\circ}C$, even though the density of M40 carbon fiber is higher. Bending strength is considerably greater than tensile strength through out the processing HTT due to the different mode of fracture. The bending and tensile strength decreases in both composites on $1000^{\circ}C$ which attributed to decrease in bulk density, thereafter with increase in HTT, bending and tensile strength increases. The maximum strength is in T700 fiber based composites at HTT $1500^{\circ}C$ and in M40 fiber based composites at HTT $2500^{\circ}C$. After attending the maximum value of strength in both types of composite at deflection HTT, after that strength decreases continuously. Decrease in strength is due to the degradation of fiber properties and in-situ fiber damages in the composite. The maximum carbon fiber strength realization in C/C composites is possible at a temperature that is same of fiber HTT. It has been found first time that the bending strength more or less 1.55 times higher in T700 fiber composites and in M40 fiber composites bending strength is 1.2 times higher than that of tensile strength of C/C composites.
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T. Mori,T.Igarashi,H. Funato,S. Ogasawara,M. Hara,F.Okazaki,Y. Hirota 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Recently, high performance power switching device realize high performance power converter. However, high speed turn-on and turn-off cause electromagnetic interference (EMI). EMI filters or wire shields decrease EMI. However, they take over space of automotive, and cost is expense. Authors have proposed a new method to decrease high-frequency noise at specific frequency band with modification of switching transient slope. In order to realize a step-down converter with modified switching slope, there are several problems such as generating PWM signal with modified slope, feasibility in a real chopper circuit, switching loss and so on. In this paper, a step-down converter applied proposed modified switching slope was successfully realized using MT (Modified Transient)-PWM generator. The operational characteristics were analyzed for resistive load.
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Effect of Silicon Infiltration on the Mechanical Properties of 2D Cross-ply Carbon-Carbon Composites
Dhakate, S.R.,Aoki, T.,Ogasawara, T. Korean Carbon Society 2004 Carbon Letters Vol.5 No.3
Effect of silicon infiltration on the bend and tensile strength of 2D cross-ply carbon-carbon composites are studied. It is observed that bend strength higher than tensile strength in both types of composite is due to the different mode of fracture and loading direction. After silicon infiltrations bend and tensile strength suddenly decreases of carbon-carbon composites. This is due to the fact that, after silicon infiltration, silicon in the immediate vicinity of carbon forms the strong bond between carbon and silicon by formation silicon carbide and un-reacted silicon as free silicon. Therefore, these composites consist of three components carbon, silicon carbide and silicon. Due to mismatch between these three components secondary cracks developed and these cracks propagate from $90^{\circ}$ oriented plies to $0^{\circ}$ oriented plies by damaging the fibers (i.e., in-situ fiber damages). Hence, secondary cracks and in-situ fiber damages are responsible for degradation of mechanical properties of carbon-carbon composites after silicon infiltration which is revealed by microstructure investigation study by scanning electron microscope.
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Effect of Silicon Infiltration on the Mechanical Properties of 2D Cross-ply Carbon-Carbon Composites
S.R. Dhakate,T. Aoki,T. Ogasawara 한국탄소학회 2004 Carbon Letters Vol.5 No.3
Effect of silicon infiltration on the bend and tensile strength of 2D cross-ply carbon-carbon composites are studied. It is observed that bend strength higher than tensile strength in both types of composite is due to the different mode of fracture and loading direction. After silicon infiltrations bend and tensile strength suddenly decreases of carbon-carbon composites. This is due to the fact that, after silicon infiltration, silicon in the immediate vicinity of carbon forms the strong bond between carbon and silicon by formation silicon carbide and un-reacted silicon as free silicon. Therefore, these composites consist of three components carbon, silicon carbide and silicon. Due to mismatch between these three components secondary cracks developed and these cracks propagate from 90˚ oriented plies to 0˚ oriented plies by damaging the fibers (i.e., in-situ fiber damages). Hence, secondary cracks and in-situ fiber damages are responsible for degradation of mechanical properties of carbon-carbon composites after silicon infiltration which is revealed by microstructure investigation study by scanning electron microscope.
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