Modification of ASTM B107 AZ31 and polypropylene surfaces with TiO2 particles using the dip-coating method

Abstract

Introduction: Magnesium alloys have been known for its biocompatible characteristics and tissue restoration properties. On the other hand, TiO2 has been found to decrease the corrosion rates of the magnesium alloys. Objective: In this work, the dip-coating technique was used to coat the magnesium alloy with TiO2 particles in order to evaluate its corrosion resistance. Methodology: The particles were analyzed by Scanning Electron Microscopy (SEM) and visual inspection. Additionally, hydrogen evolution tests were performed to understand the effect of adding TiO2 in corrosion rates of Mg-alloys. Results: The results showed the positive effect of TiO2 in the improvement of the ASTM B107 AZ31B Mg alloys corrosion by an indirect measurement through hydrogen evolution tests. The bare ASTM B107 AZ31B showed a corrosion 29 times faster compared to the coated alloy. The thickness of the coatings obtained using the dip-coating method is thinner than 20 nm. Conclusions: TiO2 particles were aggregated on the surface of the ASTM B107 AZ31B alloy with a controlled speed. SEM images have shown the improvement of the coating when the H2O concentration in the sol increased. Another important parameter is the withdrawal speed during the dip-coat process which was found to be better at a speed of 3mm/min. Hydrogen evolution in the acid solution showed that coated ASTM B107 AZ31B has less hydrogen production during the corrosion test. The dip-coating technique can also be used to coat polypropylene discs entirely.

Keywords

• Dip-coating
• corrosion
• Mg alloys
• TiO2 particles
• hydrogen evolution