Forming of Aluminum Foam Using Light-Transmitting Material as Die during Foaming by Optical Heating

Aluminum (Al) foams are expected as components of vehicles and construction materials. Among the several routes for fabricating Al foams, a precursor foaming route has been commonly used to produce Al foam. In this study, optical heating, which can directly heat a precursor, was employed through light-transmitting materials of glass and sapphire to obtain ADC12 (Al-Si-Cu alloy) foam. Fundamental investigations on the forming of the ADC12 foam using a light-transmitting material as a die, which can transmit light during foaming, were conducted. From the free foaming of the ADC12 precursor by optical heating through the glass, through the sapphire and without those materials, it was found that, although a slight energy loss was observed, the ADC12 precursor can foam by optical heating through the light-transmitting materials. In addition, it was indicated that a similar foaming behavior was observed with the generally used electric furnace except that the foaming time was much shorter by the optical heating. Furthermore, from the foaming of the ADC12 precursor by optical heating through the light-transmitting materials, which restrict upward expansion, a flat ADC12 foam can be obtained. The pore structures similar to those of the free foaming were observed. In this forming process, cracks were observed in the case of the glass during the cooling of the ADC12 foam, which was not observed in the case of the sapphire. Therefore, it was indicated that sapphire can be used as the die for the forming of the ADC12 foam during the foaming.