Abstract
In this study, the synergistic effects of NH4HF2, sodium phytate (Na12Phy), K2ZrF6, and treatment time on corrosion resistance of a micro-arc oxidation (MAO) treated magnesium alloy and the entrance mechanism of P, F, and Zr into anodic coatings were investigated using an orthogonal method. In addition, the roles of NH4HF2, Na12Phy, and K2ZrF6 on coating development were separately studied. The results show that NH4HF2 and Na12Phy, the corrosion inhibitors of magnesium alloys, are beneficial but K2ZrF6 is harmful to developing anodic coatings. The corrosion resistance of MAO coatings is synergistically determined by coating characteristics, though the coating thickness plays a main role. Na12Phy significantly improves but NH4HF2 decreases the corrosion resistance of MAO coatings, while excess high K2ZrF6 is harmful to the coating corrosion resistance. Treatment time can increase the coating thickness but is the least important factor in corrosion resistance. During MAO, NH4HF2, Na12Phy, and K2ZrF6 take part in coating formation, causing P, F, and Zr to compete with each other to enter into anodic coatings.
Highlights
Fractures and bone defects occur frequently due to road traffic accidents and sports injuries [1].Magnesium alloys appear to be the most promising biomedical metal due to their several advantages over the permanent metallic materials currently in use, including similar density and Young’s modulus to human bone, good biocompatibility, and many functions of Mg ions in vivo [2]
The main research is presented as follows: (1) the synergetic effect of NH4 HF2, Na12 Phy, K2 ZrF6, and treatment time on the corrosion resistance of Micro-arc oxidation (MAO) coatings was investigated by an orthogonal method; (2) the influences of NH4 HF2, Na12 Phy, and K2 ZrF6 on coating development capability were investigated by observing surface morphology and measuring the Icorr values of untreated AZ31B alloy in corresponding solutions; and (3) the entrance mechanisms of P, F, and Zr into MAO coatings were deduced according to the experimental results, electrolyte properties, and MAO characteristics
The results showed that coating development on magnesium alloy in a used solution was determined by electrolyte component and Icorr of untreated AZ31B measured in the solution
Summary
Fractures and bone defects occur frequently due to road traffic accidents and sports injuries [1]. The performance of MAO coatings is determined by several factors, including the composition and concentration of selected electrolytes, the applied electrical parameter, and the substrate [2,7,8,9,10]. The main research is presented as follows: (1) the synergetic effect of NH4 HF2 , Na12 Phy, K2 ZrF6 , and treatment time on the corrosion resistance of MAO coatings was investigated by an orthogonal method; (2) the influences of NH4 HF2 , Na12 Phy, and K2 ZrF6 on coating development capability were investigated by observing surface morphology and measuring the Icorr values of untreated AZ31B alloy in corresponding solutions; and (3) the entrance mechanisms of P, F, and Zr into MAO coatings were deduced according to the experimental results, electrolyte properties, and MAO characteristics
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