Heat insulation potential of metallic composites confirmed

The finding from North Carolina State University researchers means the CMF is especially promising for use in storing and transporting nuclear material, hazardous materials, explosives and other heat-sensitive materials, as well as for space exploration.

"The presence of air pockets inside CMF make it so effective at blocking heat, mainly because heat travels more slowly through air than through metal," said Afsaneh Rabiei, a professor of mechanical and aerospace engineering at NC State and corresponding author of a paper on the work published in the International Journal of Thermal Sciences.

According to NC State, the composite metal foam consists of metallic hollow spheres - made of materials including carbon steel, stainless steel or titanium - embedded in a metallic matrix made of steel, aluminium or metallic alloys.

"We have developed two technologies for manufacturing CMFs," Rabiei said. "One is based on casting a low melting point matrix material, such as aluminium, around hollow spheres made of a material with a higher melting point, such as steel. This creates aluminium-steel CMFs, for example. The other technique is based on sintering…the matrix powder around prefabricated hollow spheres. This creates CMFs such as steel-steel, which consist of steel hollow spheres in a steel matrix."