Electrophoretic Deposition of Chitosan–Hydroxyapatite Films and Their Electrochemical Behavior in Artificial Plasma

Abstract

The electrochemical behavior of chitosan–hydroxyapatite films deposited on Ti CP was evaluated. Hydroxyapatite was synthesized from eggshell at different precipitation pH conditions. The films were deposited on the Ti CP surface from chitosan–hydroxyapatite solutions by means of electrophoretic deposition. The hydroxyapatite content of the solutions varied from 0 to 20 g/L. The different films obtained were evaluated by means of electrochemical measurements such as polarization curves, open circuit potential measurements, polarization resistance, and electrochemical impedance. The results obtained showed that regardless of the precipitation pH, it is possible to obtain pure hydroxyapatite from a waste such as eggshell. The incorporation of hydroxyapatite within the chitosan structure allows for improvement of the electrochemical performance of the bare Ti CP surface. It was observed that the passive zone was achieved at lower current densities, and that the stability zone of the passive layer increased. Electrochemical impedance analyzes showed that there is an improvement in corrosion resistance due to a more controlled growth of the passive layer that allows for the formation of a dense and compact film.

Synthesis, characterization, synergistic inhibition, and biological evaluation of novel Schiff base on 304 stainless steel in acid solution

“…In low-frequency regions in which the frequency is less than 100 Hz, the phase angles of impedance in different stages are similar. When the frequency is higher than 100 Hz, there is a significant difference between the phase angles of different impedances 32 , 33 . The absolute value of the phase angle increases constantly with more negative values leading to more protection occurring.…”

“…The second time constant shows an increase in its maximum phase angle and a shift to lower frequencies. This behavior may be associated with the characteristics of the passive layer formed on MBT + KI; it is commonly accepted that the passive layer has a bilayer structure where the external part is porous (first time constant) and the internal part is compact and dense (second time constant) and therefore it presents the largest phase angle 32 , 33 . This result can reveal that there is more than one occurred electrochemical process, and the growth of more resistive MBT and MBT + KI layers adsorbed onto the SS surface, forming protected films.…”