Hydroxyapatite reinforced surface modification of SS-316L by microwave processing

Abstract

The current study was focused to modify the surface layer of stainless steel (SS-316L) for enhancing its bioactivity by reinforcing hydroxyapatite (HAp) powder through exploiting the principle of hybrid Microwave Heating (MH) technique. The modified substrates were subjected to post heat-treatment at 400 °C and 700 °C for 1 h. The microstructural analysis of the modified composite layer revealed the existence of HAp particles along with some reaction induced products primarily in the iron-based austenite dendritic matrix. The heat-treated substrates showed a higher microhardness value than that of as-deposited substrates due to densification of the modified layer after heat-treatment. The porosity, surface imperfections and flaws were reduced after heat treatment. The scanning electron microscopy (SEM) images taken over the modified and unmodified SS-316L after immersion test in simulated body fluid showed rapid apatite forming ability on the modified substrates. The apatite growth ability of the modified substrates was reduced after heat treatment performed at 700 °C due to a reduction in the amorphous phase and porosity contents.