Porous aluminum material by plasma spraying

Abstract

The feasibility of forming porous metallic materials by the plasma spraying process was studied. The process involved the co-spraying of two materials: aluminum (Al) and calcium oxide (CaO), the former being the metallic phase that eventually was retained as the porous structure, while the latter being the sacrificial phase was removed giving rise to pores in the Al matrix. For this the Al and the CaO powders of four different compositions were blended and plasma sprayed on a mold cavity. The CaO was dissolved from the sprayed structure by treating in either water or glycerol. The surface and cross sectional microstructure of the specimens after treatment in water and glycerol showed a more or less uniform pore distribution. The dissolution of CaO, leading to the porous microstructure was confirmed by the X-ray diffractometry. In the XRD spectra, the specimens in the as-sprayed untreated condition exhibited peaks corresponding to both CaO and Al, while, the peaks corresponding to CaO were absent in specimens after water and glycerol treatments confirming CaO dissolution. The study clearly showed that porous aluminum material could be manufactured by plasma spraying.