Microwave processing and characterization of alumina reinforced HA cladding for biomedical applications

Abstract

The present work comprises of enhancing the bioactivity of the SS-316L substrate by Hydroxyapatite (HA) + 10 wt% Al2O3 (HA10AL) powder using microwave supported surface modifications techniques. The microwave supported surface modified layer has a thickness of around 0.8 mm with the exposure time of 15 min. The surface modified specimens were heat treated at different temperatures (400 °C, 600 °C and 800 °C) for 2 h. Various characterizations tools were employed to characterizing the microwave supported surface modified specimens (as-deposited along with heat-treated). The microstructural study revealed the presence of HA and reaction induced HA phases in the inter-dendritic regions of the Fe-based austenite dendrite matrix. It has been observed that porosity generally decreases after the heat treatments due to faster diffusion of atoms, which fills the pores and voids, whereas the hardness showed the increasing trends with heat-treatment temperature. XRD spectra shows the presence of HA and Al2O3 phases along with iron (Fe), calcium iron phosphate (Ca19Fe2(PO4)14), iron phosphide (Fe2P), along with main iron nickel (Fe-Ni) based matrix at high temperature in all the microwave supported surface modified specimens. The apatite layer was successfully formed on the microwave supported surface modified specimens at all conditions after immersed in simulated body fluid (SBF) test. It was found that apatite formation was reduced with an increase in heat-treatment temperature due to reduction in porosity and amorphous phase (tri-calcium phosphate).