Hydrophobic Carbonate Coatings on Pure Biodegradable Mg by Immersion in Carbonated Water: Formation Mechanism

• Published in: Applied sciences Vol. 12; no. 22; p. 11674
• Main Authors: Popa, Monica, Anastasescu, Mihai, Gifu, Ioana Catalina, Calderon Moreno, Jose M.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-11-2022
• Subjects: Alloys; Aqueous solutions; Atomic force microscopy; Biodegradability; Biodegradable materials; Biodegradation; Bones; Brucite; Calcite; calcium carbonate; carbonatation; Carbonates; Carbonation; Coatings; Contact angle; Coral reefs; Corrosion resistance; Green chemistry; Hydrophobicity; hydroxycarbonate hydrate; Immersion; Implants; Laboratories; Magnesium; Magnesium hydroxide; medical alloys; Microcrystals; Microscopy; Nanoparticles; Nucleation; Physiology; protective film; Software; Spectroscopy; Spectrum analysis; Submerging; Wettability
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app122211674

Mg is one of the few materials of choice for biodegradable implants, despite its rapid degradation when used without surface protection treatment. This study presents the effect of carbonation time on the formation of hydrophobic carbonate coatings grown on pure magnesium using a simple, green chemical conversion method in carbonated water. The evolution of the coating with immersion time in carbonating solution was studied in order to ascertain the mechanistic of coating formation by Raman and EDS spectroscopy, XRD, SEM and AFM microscopy. Wettability was investigated by contact angle measurements. The formation mechanism of the hydrophobic coating involves the surface nucleation of carbonates mediated by the dissolution of the native corrosion product, brucite Mg(OH)2, surface conversion into hydroxycarbonates, surface calcite nucleation and growth by attachment of nanoparticles, leading to the lateral growth of a continuous carbonate coating layer of intertwined calcite microcrystals.