The effect of nitric acid surface treatment on CaP deposition of Ti6Al4V open-cell foams in SBF solution

The effect of nitric acid surface treatment on CaP deposition of an open-cell Ti6Al4V foam (60% porous and 300-500 m in pore size), prepared by means of the space holder method using 94 and 66 μm average particle size powders, was investigated in a simulated body fluid (SBF) solution up to 14 days. Although, nitric acid surface treatment did not change the foam flat surface roughness values significantly, it increased surface area difference greatly by introducing nano scale undulations on the surface. The increased surface area difference was found to be more pronounced in smaller particle size foam samples. A continuous relatively thin CaP coating layer formed after 5 and 14 days of SBF immersion in nitric acid surface treated small and larger average particle size foam specimens, respectively. Whereas, the cells of untreated foam specimen were observed to be filled with CaP precipitates and a continuous CaP layer development was found after 14 days of SBF immersion. These results were also confirmed with the grazing incidence XRD and FTIR analysis of SBF immersed specimens.