鋳造プリカーサ法によるポーラスアルミニウムの作製

抄録

This study proposes a casting precursor method for low-cost manufacture of large aluminum foams with complex shapes. We experimentally investigated whether a precursor with low porosity can be used to fabricate an aluminum foam with high porosity. Pure aluminum powder and alumina powder as a thickening agent were added to a molten ADC12 aluminum alloy, and the melt was mixed. Then, titanium hydride powder as a foaming agent was added to the melt, and it was mixed again. The melt was poured into a copper mold and a columnar foamable precursor was obtained. An aluminum foam with maximum porosity of 80% was obtained by heating the precursor (1 mass% pure aluminum powder, 1 mass% alumina powder, 1.5 mass% titanium hydride powder and 96.5 mass% ADC12 aluminum alloy) at 948 K for 7 min. The compressive behavior of the produced aluminum foam was close to that of an ADC12 aluminum foam made in previous research, indicating that the new approach has promise. However, the precursor had about 40% porosity because the titanium hydride decomposed during casting. Thus, we attempted to prevent decomposition of the foaming agent during the casting process. The porosity was increased by increasing the amount of pure aluminum powder added. In contrast, increasing the amount of alumina powder added had almost no effect on porosity because the alumina particles did not disperse fully in the melt due to their low wettability with alumina. The titanium hydride powder was heat treated to prevent its decomposition during the casting process. The heat-treated powder decreased the porosity of the precursor, but the porosity of the aluminum foam also decreased. A low-cost foaming agent with a decomposition temperature higher than that of titanium hydride is needed for low-cost manufacture of aluminum foam by the casting precursor method.