Calcium phosphate deposition on surface of porous and dense TiNi alloys in simulated body fluid

Abstract

Porous and dense TiNi alloys were successfully fabricated by powder metallurgy (P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide (SiC) paper, acid etching and alkali treatment were employed to produce either irregularly rough surface or micro-porous surface roughness. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) attached to SEM were used to characterize surface structure and the Ca-P coatings. Effects of the above surface treatments on the surface morphology, apatite forming ability were systematically investigated. Results indicate that all the above surface treatments increase the apatite forming ability of TiNi alloys in varying degrees when soaked in simulated body fluid (SBF). More apatite coatings formed on TiNi samples sintered at 1050° and 1100° due to their high porosity and pure TiNi phase that is beneficial to heterogeneous nucleation. Furthermore, more uniform apatite was fabricated on the sample sintered from the mixture of Ni and Ti powders.