Abstract
A new process for producing porous aluminum by the foaming technique was developed. In the process, molten aluminum into which Ca has been added before the stage of viscosity rise is stirred to disperse oxide films into the melt. Adding Ca results in considerable shortening of the time for viscosity rise because of promoting oxidation of the melt. Another advantage of Ca addition includes that the foaming agent is mixed easily and quickly in the melt by the vortex method. This also allows to diminish a required amount of expensive foaming agents such as TiH2 and ZrH2 and to utilize economical foaming agents such as volcano ash (Shirasu). Only about 0.4%Ca is required both for viscosity rise of the melt and mixing of foaming agents. The optimum viscosity of the melt for foaming is about 8.6cP.
