Aluminum foam is a promising material with a unique combination of mechanical and operational properties: low specific weight, low thermal conductivity, the ability to absorb acoustic and electromagnetic oscillations, the ability to deform under constant load. Currently, the most used methods for production of foam aluminum are methods based on mixing a gas or a poropore into an aluminum melt and forming a porous structure during the solidification of the aluminum melt. An alternative to this technology is the formation of a porous structure due to the use of soluble granules which are pre-filled in a mould, and then after impregnation of the granules with aluminum melt and solidification of the casting, they are leached. Studies on the formation of porous aluminum by impregnating with an aluminum melt a mould with soluble granules confirmed that the cooling rate of the melt depended on the thermal conditions of the casting (temperature of the mould with granules and the temperature of the cast alloy), as well as on the size of water-soluble granules, their thermal-physical properties and their packing density in the mould. Calculated and experimental studies have shown that the cooling rate of the melt in the mould with water-soluble granules is higher by 1.8-10 times than in the casting of solid aluminum castings. Metallographic studies of the structure of porous aluminum demonstrated that the grain size was by 2-4 times smaller than solid casting one.
Kovtunov et al. (Wed,) studied this question.