Preparation of Crystalline Hydroxyapatite Thin Films by PLD for Biomedical Implant Coating Applications

All major precursors for the orthopedic implants: stainless steel (316L), cobalt-based alloys, and titanium-based alloys have main problems at the long-term functioning. Key problems are degradation of metals in human body’s fluid, corrosion of implants, and release of toxic elements. Coating of the metallic implants with inorganic ceramic-based materials such as hydroxyapatite (HAP): Ca₁₀(PO₄)₆OH₂ can efficiently diminish the listed hazards. Since HAP partially exists in human bone, it can enhance biocompatibility, bone-implant adhesion, and reduce the release of toxic elements. However, conventional techniques of coatings such as RF Magnetron Sputtering, Plasma Spraying, Ion-Beam deposition struggle in producing crystalline structure, which is an essential parameter for the resistance against degradation in saline human body environment. In this work, we report the possibility of obtaining crystalline HAP films by the Pulsed Laser Deposition technique. We also analyze the film’s crystallinity and microstructure depending on annealing and substrate temperatures ranging from 25º C to 900º C. The XRD results show that substrate temperature directly influences the crystallinity, as at higher substrate temperatures more Bragg diffraction planes have emerged. Furthermore, the analysis of surface topography, composition, and structure of HAP coatings by SEM with energy dispersive x-ray, and FTIR will be presented. We propose these films for further study on biodegradation and fatigue resistance tests on Biomedical implants.