Published online by Cambridge University Press: 15 February 2011
A novel method of fabricating low-density hollow sphere metallic foam has been developed. Utilizing pre-existing technology, thin-wall, hollow oxide spheres, ∼ 2mm in diameter, were formed from powder slurries with a coaxial nozzle process. Oxide foams were constructed by bonding sintered spheres at points of contact and firing. The oxide foams were reduced to the metallic state in a hydrogen atmosphere. Successful precursor compositions for transformation included NiO, Cu2O, and NiO-Cu2O. After reduction, the metal foams were sintered to increase strength and resulting foam densities were generally 10–20% of theoretical density. Wall thickness of the spheres which constitute the foams ranged from 50–100 μ m. Nickel foams were crushed under uniaxial compressive stress, and mechanical properties (yield stress, elastic modulus, and energy absorption) were investigated under varying density in order to determine parametric relationships to compare to existing models of foam properties. The effects of sintering, reduction, and compressive deformation on the microstructures were examined with SEM and EDS.