Open-cell Aluminium Foams Reinforced by Alumina Nanoparticles

In this research, the effects of Al2O3 nanoparticle additions on relative density, porosity, microstructure and compressive properties of aluminium foams, fabricated by powder metallurgy and CaCO3 foaming agent, were investigated. To this end, aluminium, Al2O3 and CaCO3 powders were mixed and compacted using cold pressing with 318 MPa to dense cylindrical precursors with 77-80% relative density. The precursors were heated at 450oC for 30 min and 1000oC for 10 min, both under the air atmosphere. Cooling in the air was employed to solidify the foams. In order to determine the effects of Al2O3 additions, the content of Al2O3 nanoparticles was varied between 0-15 wt.%. Finally, the heat treated samples were used for microstructure investigation and uniaxial compression test. FESEM micrographs indicated an open-cell microstructure with interconnected pores smaller than 100 micron. Measurements showed that Al2O3 additions didn’t affect the linear expansion. In addition, agglomeration of Al2O3 and CaCO3 particles occurred in samples with 15 wt.% Al2O3. Foams containing 3 wt.% Al2O3 showed the highest relative density (65.81%), lowest porosity (34.14%), the most uniform microstructure and highest compressive properties. Increasing of Al2O3 from 3-15 wt.% resulted in gradually decrease of microstructure uniformity, compressive strength (42.10-23.60 MPa) and densification strain (45.75-34.08%).

Keywords:

Nano-composite aluminium foam , Alumina Nanoparticle , Powder metallurgy microstructure , Compressive properties