Investigating the effect of salicylate salt in enhancing the corrosion resistance of AZ91 magnesium alloy for biomedical applications

Abstract

Abstract:The pretreatment process plays a vital role in the development of a robust protective layer on magnesium alloys. This work presents a novel insight into the pretreatment of magnesium alloy AZ91 in alkaline silicate solution by anodic oxidation in the presence of C 7 H 5 NaO 3 (sodium salicylate) to enhance surface resistance and introduce a passive biolayer. The electrochemical corrosion behavior of protective layers prepared at different voltages was evaluated by electrochemical impedance spectroscopy (EIS) in SBF solution. The Nyquist impedance plots for anodized films, which consist of a mixture of magnesium silicate and salicylate, indicate a significant corrosion protection ability of the layers formed under optimized conditions; an increase of the real impedance from the value of ~2 kΩ.cm 2 for the bare alloy surface to about 10-12 kΩ.cm 2 for the anodized film can be observed. The results indicate that surface modification by anodizing in silicate electrolyte in the presence of sodium salicylate is an alternative pretreatment to improve the corrosion resistance of AZ91.

Alternating Current Electrophoretic Deposition of Chitosan–Gelatin–Bioactive Glass on Mg–Si–Sr Alloy for Corrosion Protection

“…Bioactive glasses (BGs) are also a good choice as a coating material for metal implants because they formed a hydroxyl-carbonate-apatite layer on the surface of the metal that increases the contact with physiological fluids . Although a lot of research work is done on hybrid biopolymer/BG coatings on stainless steel and titanium, − very little work is carried out on Mg implants with AC-EPD. , Many coating techniques with pretreatment, such as anodization, micro arc oxidation, laser cladding, surface melting, electrochemical deposition, and EPD, are utilized to enhance the corrosion resistance that increases the biocompatibility of the substrate. − AC-EPD is the recent approach with its versatile parameters to form a thick and homogeneous layer of biopolymer/BG on the implant surface. Mostly biopolymers such as CS–G mixed with BG make a composite that becomes negatively charge and are used for composite metal interaction on the anode …”

Investigations on the surface topography, corrosion behavior, and biocompatibility of friction stir processed magnesium alloy AZ91D

“…However, the corrosion resistance of AlN and TiN sputtered AZ91 alloy is higher in 3.5% NaCl solution than in Hank's simulated body fluid solution [19]. The passive bio-layer formed by an anodic oxidation process in the presence of sodium salicylate, sodium hydroxide, and sodium silicate improves the corrosion resistance of AZ91 alloy [12]. The formation of adherent magnesium silicate and magnesium salicylate layer improves the corrosion resistance of the AZ91 alloy.…”

“…AZ91 alloy exhibits excellent biocompatibility and corrosion resistance in in vivo experiments [2,4,6,[8][9][10][11][12][13][14]. The recommended corrosion rate for biodegradable bioimplant materials is less than 0.5 mm year −1 .…”

Impact of processing parameters in plasma electrolytic oxidation on corrosion resistance of magnesium alloy type AZ91

“…Anodizing, where aluminium is coated on magnesium, is among the traditional methods, which has been used for a while, to improve the corrosion resistance, however, because the mechanical properties of aluminium are relatively low, for example, yield strength, hence, other attempts have been conducted, such as adding nanoparticles and forming a hybrid coating, using plasma electrolyte oxidation (PEO) 9–18 …”

“…Francis et al 16 studied the pre‐treatment of magnesium alloy type AZ91 in alkaline silicate solution by anodic oxidation in the presence of sodium salicylate. The electrochemical corrosion behavior of anodized films was investigated using electrochemical impedance spectroscopy (EIS).…”