Surface Characterization and Corrosion Resistance of Biomedical AZ31 Mg Alloy Treated by Microarc Fluorination.

Lin Sun,Jia Yi Cui,Teng Wang,Bing Cheng Zhao,Heng Bo Jiang,Eui-Seok Lee,Feng Li,Hongxin Cai,Qianqian Zhang,Shuxin Zhang

doi:10.1155/2020/5936789

Abstract

The application prospect of biodegradable materials is being studied extensively. However, the high corrosion rate and its alloys in body fluids have been major limitations of the application of pure Mg (magnesium). To improve corrosion resistance of biodegradable AZ31 Mg alloy, we adopted microarc fluorination within a voltage range of 100-300 V in 46% hydrofluoric acid. To obtain morphologies, chemical compositions, and structural characteristics, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were performed, respectively. Results showed that the coating was mainly composed of MgF2. Electrochemical corrosion and immersion tests proved that the corrosion resistance of MAF-treated AZ31 Mg alloy was significantly improved compared with untreated AZ31 Mg alloy in HBSS (Hank's Balanced Salt Solution). Current densities of AZ31, MAF100, MAF150, MAF200, MAF250, and MAF300 were 342.4, 0.295, 0.228, 0.177, 0.199, and 0.212 μA/cm2, respectively. The roughness test indicated that samples under MAF treatment of 200 V, 250 V, and 300 V had large surface roughness. Meanwhile, the contact angle measurement and surface free energy test suggested that those samples had smaller contact angle and higher SFE than Ti. Thus, MAF-treated AZ31 Mg alloy might have promising application in various fields.

Highlights

In orthodontic treatment of oral cavity, microimplant nails are often used in anchorage treatment
Corrosion resistances of AZ31 and microarc fluorination (MAF)-treated AZ31 Mg alloys were determined with the open circuit potential and potentiodynamic polarization test
Based on chemical element compositions on surfaces of AZ31, MAF100, MAF150, MAF200, MAF250, and MAF300 based on energy-dispersive X-ray spectroscopy (EDS) analysis, the percentage of fluoride increased within increasing voltage

Summary

Introduction

In orthodontic treatment of oral cavity, microimplant nails are often used in anchorage treatment. The density of metallic magnesium is 1.7-2.0 g/cm, similar to the density (1.8-2.1 g/cm3) of a natural bone These characteristics indicate that Mg and its alloy are promising bone implant materials [6]. Their degradation rate is too high to produce microimplant nails. Scanning formed on the metal surface through metal passivation treatment, metal plating [7, 8], or metal surface fluorination [9] can delay the degradation of metal. These methods can maintain good mechanical properties [10, 11]. Limited by ethical aspects and laboratory conditions, it is impossible to use animal models to simulate in vivo experiments

Materials and Methods

Results and Discussion

F K Mg K Al K Zn K

Conflicts of Interest