Hybrid material makes the aerospace-grade

The material combines steel composite metal foam (CMF) and epoxy resin to form a hybrid material dubbed ‘infused CMF’ by the team that developed it at North Carolina State University (NC State).

“While infused CMF is about the same weight as aluminium, it is tougher and has other characteristics that make it more appealing from a flight performance, safety and fuel efficiency standpoint,” said Afsaneh Rabiei, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at NC State.

CMF consists of hollow, metallic spheres made of materials including stainless steel or titanium that are embedded in a metallic matrix made of steel, aluminium or metallic alloys.

For their latest CMF study, the researchers used so-called steel-steel CMF, where the spheres and the matrix were made of steel. Previous work has found the metal foam can withstand .50 calibre rounds, resist high temperatures, and block blast pressure from high explosive incendiary rounds.

The infused CMF is made by immersing the steel-steel CMF in a hydrophobic epoxy resin and using vacuum forces to pull the resin into the hollow spheres and into much smaller pores found in the steel matrix. According to NC State, this results in about 88 per cent of the CMF’s pores being filled with epoxy resin.