Investigation of the effect of crystallographic texture on the corrosion properties of hydroxyapatite-coated titanium alloy

In this study, the effect of substrate crystallographic texture on the properties and corrosion behavior of hydroxyapatite (HAp) coatings electrodeposited on Ti-۶Al-۴V alloy was investigated. HAp coatings were deposited on three orthogonal surfaces of the recrystallization annealed specimens, and the morphology, structure, and electrochemical behavior of the coatings were evaluated by SEM, XRD, FTIR, surface profilometry, EIS, and Tafel polarization tests. The results revealed that the crystallographic texture of the substrate significantly influences the morphology, thickness, porosity, and protective performance of the HAp coating. The coating formed on the surface where high-energy basal planes were oriented parallel to the surface was more non-uniform and porous, exhibiting the lowest protection efficiency of ۰.۵۳%. In contrast, the orientation of {۱۰̅۱۰} planes parallel to the surface resulted in a denser coating with a thickness of up to ۵۷.۷ μm and a protection efficiency of ۳۱.۵%. The EIS results further indicated an increase in charge transfer resistance and a decrease in electrolyte permeability for the denser coatings, with the pore charge transfer resistance increasing from ۵۱.۵ to ۱۴۷ kΩ·cm². These findings demonstrate that, independent of microstructure, the substrate crystallographic texture plays a significant role, through its influence on the oxide layer formation and the nucleation and growth processes of HAp, in determining the structure and protective performance of the coating.

کلیدواژه ها:

Crystallographic Texture ، Electrodeposition ، Hydroxyapatite ، Corrosion ، بافت کریستالوگرافی ، رسوب دهی الکتریکی ، هیدروکسی آپاتیت ، خوردگی