Effect of surface active agents on the performance of hydroxiapatite coating electrodeposited on Mg-3 Zn-0.8 Ca alloy

The effect of different concentrations of both polyethylene glycol (peg) (0.01-0.2 g/l) and sodium lauryl sulfate (sls) (0.01-0.1 g/l) on the performance of fluoridated hydroxiapatite (fha) coating electrodeposited on mg-0.8 zn-0.2 ca alloy was addressed. the fha coating was evaluated in simulated body fluid (sbf) using open circuit potential,potentiodynamic polarization and electrochemical impedance spectroscopy (eis) techniques. surface characterization of the fha coatings was performed using scanning electron microscopy (sem) and energy dispersive x-ray spectroscopy (eds) techniques. potential measurements during electrodeposition of fha showed that more stable deposition potential and hence more stable coating growth is exhibited in the presence of peg. eis and potentiodynamic measurements revealed that peg increases the level of passivation of the fha layer more than sls. both additives have resulted in a shift of the ecorr to more noble values,more grain refinement of fha coatings,better compactness and more corrosion resistance. the enhancement mechanism of peg and sls was discussed.