Papers by Author: Yong Bum Choi

Abstract: In order to infiltrate the molten aluminum alloy to the reinforcement preform by low pressure in casting process and acquire the high performance composites with high density, the effect of the ultrasonic vibration on the infiltration was investigated by model experiments using clear solution and glass or aluminum borate preform, which is correspond to a molten matrix and reinforcement, respectively. Ultrasonic vibration improves the wettability of liquid polyester resin on glass plate, dramatically. The final infiltration height and infiltration speed of liquid polyester resin in glass capillary were improved by the ultrasonic vibration. Furthermore, the infiltration speed of water to aluminum borate preform accelerated by ultrasonic vibration. This effect was more remarkable, when the infiltration height is lower or infiltration time is shorter. In actual, the molten aluminum alloy infiltrate to SiC preform using ultrasonic vibration easily and acquire the high dense composites without pores.

Abstract: 20 vol.% aluminum borate whisker (Al18B4O33w) reinforced AC4CH alloy composite was fabricated by squeeze casting method. The matrix is controlled its impurities, which make metal alloys, especially AC4CH alloy that is made by restraining 0.2% Iron and aluminum to make a matrix material. The perform of composite materials was made from Al18B4O33w with 5% regulated three kinds of inorganic binders, SiO2, Al2O3 and TiO2 sol, respectively and then sintered at 1373K. The composites were obtained by squeeze cast infiltration of the molten alloy to the perform. Then it was squeeze casting into the matrix. The status of adhesions of whisker perform was Observed by SEM. Micro-Vickers hardness and tensile properties at the room temperature were estimated. Al18B4O33w/AC4CH composites containing TiO2 sol has excellent properties on tensile properties and micro-vickers hardness compared with the other composites without inorganic binder, containing SiO2 and Al2O3 sol inorganic binder.