Q2. What is the advantage of magnesium in relation to other metallic implants?
Another advantage of magnesium in relation to other metallic implants is the degradability of magnesium alloys which offers the possibility of better physiological3repair and better reconstruction of vascular compliance with minimum inflammatory response.
Q3. What is the electrochemical result of the HF-MF?
The best electrochemical results at the initial stages, obtained in samples immersed in NaCl with respect to the PBS medium, can be attributed to the electrochemical dissolution of Mg thus favouring the production of OH- ions as a result of the hydrogen gas formation in the cathodic reaction.
Q4. What is the effect of OH- ions on the corrosion of the samples?
The presence of OH- ions causes an increase of pH in the medium and facilitates the formation and precipitation of MgO and/or Mg(OH)2 as corrosion products.
Q5. What is the effect of the Al in the AZ31 alloy?
The Al present in the AZ31 alloy, 3% in weight, increases the corrosion resistance of Mg by stabilizing the passive layer [14, 25-26].
Q6. What is the drawback of magnesium alloys?
The major drawback of magnesium alloys is that they tend to corrode very quickly in the physiological pH (7.4-7.6) environment thereby losing their mechanical integrity before the end of the period necessary for bone tissue healing.
Q7. What is the main advantage of magnesium alloys?
Attempts at improving the corrosion resistance of Mg alloys by reducing grain size have been proposed by means of laser fusion technology.
Q8. What is the current in type II?
The current remains low during 20 s for Type II in NaCl and then increases due to the localised corrosion induced by chloride ions.
Q9. What is the way to avoid second phases?
the10relatively small amount of Al ensures the presence of only one phase in the alloy thus avoiding second phases that may be detrimental for the corrosion behaviour.
Q10. What is the way to reduce the corrosion of a metal?
The application of Mg and its alloys as biomaterial for temporal implants in the form of plates and screws would be effective when the corrosion kinetics are understood and controlled in body fluids.
Q11. What criteria were used in estimating the quality of the fitting?
The criteria used in estimating the quality of the fitting were evaluated firstly with the lower chi-square value, and secondly with the lower estimative errors (in %) for all the components.
Q12. What is the second arc observed for Type II samples?
The second arc observed for Type II samples (Figure 6) in both solutions, NaCl and PBS, could be attributed to mass transport in the solid phase due to the growth of the corrosion product layer [14], facilitated by the finer grain size.
Q13. What is the diameter of the first capacitive arc at high frequency?
The diameter of the first capacitive arc at high frequency (Figures 5 and 6) can be ascribed to the R1 value that includes the resistance of the passive film and/or the layer of corrosion products [29].
Q14. What is the polarization curve for Type The authorAZ31?
The polarization curves obtained in 8 g/l NaCl (Figures 2 and 3) show a pseudo-passive region followed by a sharp current increase at the breakdown potential due to the action of chloride.
Q15. What is the reason why the OH- ions are not captured?
In the case of AZ31 samples immersed in PBS, the phosphate ions ((HPO4)2-) possibly capture the OH- that is produced by the cathodic12reaction and consequently the high alkaline pH (that favours the massive precipitation of Mg hydroxide) cannot be reached.
Q16. What is the method for determining the corrosion behaviour of type The authorand II samples?
Results for the initial stages of immersion show that the corrosion behaviour of Types The authorand II samples depends on the testing media, NaCl or PBS.
Q17. What is the impedance plot for Type The authorsamples?
In the impedance plot for Type The authorsamples (Figure 5), a depressed semicircle at high frequencies and an inductive loop at low frequencies are observed, independently of the medium, PBS or NaCl.
Q18. What is the effect of the change of Ecorr over time?
The change of Ecorr over time (Figure 10) is more important in Type II and is probably related to its higher surface reactivity being more evident during the first hours.
Q19. What is the simplest way to simulate the LF range of the AZ31 alloy?
In order to simulate the low frequency (LF) range, a second branch is added in the Randles circuit (Figure 9b), in which an9inductive element L1, appears to describe the corrosion behaviour at low frequencies.