Preparation and characterisation of electrophoretically deposited hydroxyapatite coatings on type 316L stainless steel

摘要

Hydroxyapatite (HAP) coatings were developed on type 316L stainless steel (SS) by electrophoretic deposition at various deposition potentials from 30 to 90 V using the stoichiometric HAP (Ca/P ratio 1.67) powder in a suspension of isopropyl alcohol. The optimum coating parameters were established at 60 V and 3 min, after vacuum sintering at 800℃. The phase purity of the coated surface was confirmed by XRD and secondary ion mass spect-rometry confirmed the presence of both Ca and P on the coated layers. The electrochemical corrosion parameters E_(corr) (open circuit potential) and pitting potentials, evaluated in Hank's solution shifted towards noble direction for the HAP coated specimens in comparison with uncoated type 316L SS. Electrochemical impedance spectroscopic investigations revealed higher polarisation resistance and lower capacitance values after immersing the coated specimens in Hanks solution for 200 h. This indicates the stable nature of the coatings formed.