Analysis of the degradation process and electrochemical behaviour of AZ31 magnesium alloy in artificial saliva

Authors

DOI:

https://doi.org/10.3989/revmetalm.166

Keywords:

Artificial saliva, AZ31, Degradation rate, EIS, HF treatment, Polarisation curves, Polarisation resistance

Abstract


This work applies a combination of immersion tests, surface analysis techniques, and electrochem­ical methods to characterise the degradation process of AZ31 magnesium alloy when it is exposed to artificial saliva for 28 days. The surface of the alloy was evaluated in two conditions: bare and with an MgF2 layer. This conversion layer was formed by soaking AZ31 in hydrofluoric acid (HF). SEM images revealed differences in the corrosion attack of the two surface conditions, specifically in the vicinity of Al-Mn intermetallic particles. Both EDS and XPS analysis indicated that the composition of the corrosion layers formed during immersion tests corresponds mainly to Mg(OH)2 and Ca10(PO4)6(OH)2 for the bare sample, whereas for the treated surface the principal corrosion product was MgCO3. The polarisation resistance (Rp) value estimated from EIS experi­ments was two orders of magnitude higher for the HF-treated samples than that of the bare samples. In addi­tion, the corrosion rate (CR) calculated from the potentiodynamic polarisation (PDP) curves was lower for the HF-treated surface than for that of the bare AZ31 surface. All results indicate that the HF-treatment on AZ31 magnesium alloy surface improves significantly its corrosion resistance in artificial saliva.

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Published

2020-06-30

How to Cite

Mena-Morcillo, E., Veleva, L., & Espadas-Herrera, L. J. (2020). Analysis of the degradation process and electrochemical behaviour of AZ31 magnesium alloy in artificial saliva. Revista De Metalurgia, 56(2), e166. https://doi.org/10.3989/revmetalm.166

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Articles