Depth Profile of IBADThin Coatings on Ti-6Al-4V Implants

Thin-film bioceramic coatings have been regarded as potential substitutes to commercially available coatings like plasma-sprayed hydroxyapatite, once desirable features such as controlled thickness and microstructure are easily achieved through a variety of processes. Objective: to depth profile two different ion beam assisted deposited thin-film Ca- and P-based bioceramic coatings (IBAD 1 vs. IBAD 2) on Ti-6Al-4V implants. Methods: the approximately 10 mm in length and 4 mm diameter implants were inserted and degassed inside the transfer chamber to 10-7 torr, and were subsequently placed inside a Kratos Axis 165 multitechnique XPS spectrometer. Survey and high resolution spectra were obtained using a 165 mm mean radius concentric hemispherical analyzer operated at constant pass energy of 160 eV for survey and 80 eV for high resolution scans. A 4 keV Ar+ ion sputter gun was employed to etch the sample surface at 2-5 min intervals, and repeated cycles of etching and XPS high resolution scans were carried out to establish elemental composition as a function of depth. Results: survey analyses revealed the presence of Ti, Al, Si, O, C, Ca, P for the IBAD 1 implant and Si, O, C, Ca, P for the IBAD 2 implant. Depth profile for IBAD 1 implants showed that Ca and P decreased to undetectable levels after 100 seconds/etch time, whereas IBAD 2 showed Ca and P after depths as long as 2450 seconds/etch time. Stoichiometry (Ca/P ratios) varied as a function of depth for both samples ranging from 1.2 to 3.6. Conclusions: according to the results obtained, it can be concluded that the IBAD 1 coating was significantly thinner than the IBAD 2 coating, and that Ca and P deposition rates vary for different stages of the bioceramic deposition through the ion beam assisted process.