SYNTHESIZATION & COATING OF HYDROXYAPATITE (HAP) ON 304 STAINLESS STEEL AND ITS CHARACTERIZATION

Abstract

An attempt has been made to synthesis a biomaterial i.e. hydroxyapatite from waste material i.e. eggshell. This material is very similar to natural bone and having best bioactivity properties. Hydroxyapatite bio-ceramic powder was synthesized using waste eggshells as calcium source by a straightforward high temperature hydrothermal method. Different calcium phosphate phases were obtained just by changing the thermal treatment. HAp is the only apatite present in the reaction products, along with minute fractions of other calcium compounds. This synthesized HAp is used for coating purpose by PLD (pulsed laser deposition) method. HAp target of composition Calo (PO4)6(OH)2 has been used to develop HA thin films on 304 SS at substrate temperature RT (room temperature) & 570°C using PLD with KrF laser source energy of 400mJ. The final product of HAp and coated HA film was characterized by X-ray diffraction (XRD), Scanning electron microscopy (FESEM/EDAX), Atomic Force Microscopy (AFM), Fourier - Transform Infrared Spectroscopy (FT-IR) & Thermal analysis (TG—DTA). HA film so obtained at RT is partially amorphous and showed lower level of crystallinity as compare to 570°C. The formation of more crystalline phase of HA was found after annealing as well. The average surface roughness was of 105-125 nm with coating thickness 1-2 μm showing that the temperature increase did not favour the growth of a finer granulated surface. Lower or higher substrate temperature provides the possibility to obtain coatings difference crystallinity, texture and roughness, thus tailoring them for various applications