Preparation of shaped aluminum foam parts by investment casting

Difficulties in producing shaped closed-cell aluminum foam parts limit the development and application of aluminum foams. The technique of shaped aluminum foam part preparation by investment casting was devel-oped in this study. The casting-foaming (CF) method, in which a precursor alloy melt (PAM) containing pre -oxidized TiH2 was made at a low temperature and poured into a heated mold at a high temperature to foam, was used for investment casting. Results show that the PAM containing pre-oxidized TiH2 at 600 celcius exhibits a 10 -min slow foaming stage, providing the opportunity to separate melt pouring and foaming operation. Shaped foam parts with thin and dense skin were obtained. Surface shrinkages at the top area of foam parts were found to be the main defect. Increasing the cooling rate of the top area and decreasing the porosity to about 60 % can significantly reduce the surface shrinkage defect. No significant difference was found in the uniformity of foam structure in height and thickness directions. Ultimately, the investment casting is proved to be suitable for producing precise aluminum foam parts with complex shapes.