Abstract
Nano-hydroxyapatite (nHA)-matrix coatings containing graphene nanosheets (GNS)-nHA were coated on Ti6Al7Nb alloys by plasma electrolytic oxidation (PEO) treatment for the improvement of their surface properties. Crystallographic properties, functional groups, and elemental analysis of coatings were characterized by XRD, ATR–FTIR, and EDS analysis. Surface morphological changes of the coated surfaces were investigated by AFM and SEM. The electrochemical corrosion behavior of the coatings was examined by using the potentiodynamic scanning (PDS) tests under in-vitro conditions in simulated body fluid (SBF). The results showed that the GNS was successfully deposited in ceramic matrix coatings on Ti6Al7Nb alloys. Also, the microstructural observations revealed that the coatings have a porous and rough structure. The XRD and ATR–FTIR quantitative analysis have proved the appearance of HA and GNS in the coating layers. An increase in the coating thickness, surface hardness, and anatase/rutile transformation rate was determined, while the GNS ratio in the coating layers was increased. The microhardness of the nHA coating reinforced with 1.5 wt% GNS was measured at 862 HV, which was significantly higher than that of GNS-free (only nHA) coating (584 HV). The best in-vitro resistance to corrosion in SBF was observed in the nHA/1.5GNS wt% coating.
Highlights
Due to the development of technology, the use of new technologies in medical science has increased, and with this integration, new developments and applications have brought many innovations in implant production
The results showed that the graphene nanosheets (GNS) additive plays an active role in the elemental response of the coating, and its effect is mainly on the change of porosity content and the structure of the HA-based layer deposited on the surface
The nHA and GNS containing hybrid coatings from electrolytes containing calcium acetate and sodium phosphate and graphene were deposited on Ti6Al7Nb alloys successfully by the plasma electrolytic oxidation (PEO) method
Summary
Due to the development of technology, the use of new technologies in medical science has increased, and with this integration, new developments and applications have brought many innovations in implant production. The results showed that the GNS additive plays an active role in the elemental response of the coating, and its effect is mainly on the change of porosity content and the structure of the HA-based layer deposited on the surface. We expected to note a change in the Ca/P ratio It could be concluded from XRD and EDS results that if the pores of the PEO treated coating have a bigger size, and lower number, the inner layer structures of the coating are transformed from amorphous to crystalline phases because of the high temperature and high pressure, and the diffusion of more Ca, P, and O ions into the coating structure [31,52].
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