Ultrafast high temperature sintering of porous metal sandwich structures

Porous metals are attractive engineering materials due to their high gas/liquid permeability, high strength-to-weight ratio, low density, and excellent energy absorption. Sandwiching a porous metal between two dense sheets can be used to achieve high strength, bending stiffness and impact resistance without sacrificing the lightweight nature of the porous metal. However, conventional fabrication of porous metal sandwich structures is slow, and can lead to weak interfaces between the core and sandwich sheets. In this work, a single step fabrication of sandwich-structured porous iron foams is achieved by ultrafast high temperature sintering (UHS) of iron powders. UHS realizes high temperature sintering within 40 s, resulting in strongly connected porous structures. In-situ oxidation of the outer surfaces results in dense oxide shells, forming porous iron sandwich structures. Mechanical testing of UHS sandwich-structured samples reveal significantly higher compressive and flexural strength and modulus compared to furnace-sintered porous samples with equivalent porosity.