Alkali pre-treatment of the Ti6Al7Nb substrate and its impact on electrochemically deposited calcium phosphate coatings

The aim of this work was to investigate the effect of alkali pre-treatment of a Ti6Al7Nb substrate on the morphology and physicochemical properties of calcium phosphate (CaP) coatings. CaP coatings were electrochemically deposited on two groups of substrates: one unmodified and the other pre-treated in a 5M NaOH solution. CaP coatings deposition was performed in a three-electrode system using a potentiostatic mode at a potential of -4 V for 1 h in an electrolyte containing 0.042M Ca(NO3)2 and 0.025M NH4H2PO4. The surface characteristics of the coatings were determined using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and contact angle techniques. Additionally, the corrosion resistance of the coatings was assessed by linear polarization resistance and potentiodynamic polarization tests in PBS solution. Morphological analysis showed that the coatings exhibited no significant differences. EDS analysis confirmed the presence of characteristic elements constituting the CaP coatings in both tested groups. Raman spectra revealed the characteristic peaks of the hydroxyapatite (HAp), amorphous calcium phosphate (ACP), and dicalcium phosphate dihydrate (DCPD) structures. Furthermore, Raman mapping confirmed the effectiveness of substrate pre-treatment, leading to the crystalline structure of the coatings. The water contact angle values indicated that pre-treatment of the substrate in NaOH increases the hydrophilicity of the deposited coatings. Regardless of the substrate preparation method, the deposited CaP coatings exhibited protective properties against corrosion under physiological conditions. The results confirmed that alkali pre-treatment of the Ti6Al7Nb alloy affects the crystallinity and the wettability of the electrodeposited CaP coatings.

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Opracowanie rekordu ze środków MNiSW, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2024).