Primary Investigation on an Iron Foam Sandwich Structure

Firstly, the slurry coating process was carried out for the polymer foam, and then the coated foam was sintered at 1160–1400 °C to yield a reticular iron foam with the pore size of 0.5–2.0 mm and porosity of 75%–95%. After this, an iron foam sandwich structure was further obtained by thermal diffusion combination of the iron foam with the stainless steel sheet treated by a surface activation. The bonding strength of the metal face-sheet and the porous core was examined by testing three samples from sintering at 1300 °C and two samples from sintering at 1160 °C. The results show that the core of the sandwich structure is well metallurgically bonded with the metal face-sheet for the sample from sintering at 1300 °C for 2 h and can not for that from sintering at 1160 °C for the same period. The analysis reveals the vacuum degree of the present sintering system (i.e., the system pressure at room temperature is less than 5 × 10⁻² Pa, and the maximum pressure may be up to 20–40 Pa during the high temperature sintering) can well prevent the oxidation of metal iron in the high temperature process of heat treatment. The face-sheet/foam-core bonding state in the sandwich structure is investigated, and the bonding strength is found to be higher than the tensile failure strength of the core foam itself.