Role of Surface Preparation in Corrosion Resistance Due to Silane Coatings on a Magnesium Alloy.

Abhishek Saxena,R K Singh Raman

doi:10.3390/molecules26216663

Abstract

Coating of an organo-silane (Bis-1,2-(TriethoxySilyl)Ethane (BTSE)) has been observed to improve the corrosion resistance of magnesium alloy AZ91D. Three different types of surface preparations have been employed before condensing the silane coating on to the substrate. Corrosion resistance was investigated using electrochemical impedance spectroscopy (EIS). A specific alkali treatment of the substrate prior to the coating has been found to improve the corrosion resistance of the coated alloy, which has been attributed to the ability of the treatment in facilitating the condensation of a relatively compact siloxane film.

Highlights

The high electronegativity of magnesium and its alloys greatly amplifies the importance of problem of corrosion as compared to that for other metals and alloys used in commercial applications [1,2,3,4]
The coatings in each case was found to be completely covering the substrate with little signs of cracks or uncoated areas as suggested by the SEM micrograph of a typical BTSE coated AZ91D (Figure 1)
EDXS spectra of freshly formed films on each of the coated substrates consisted the characteristic peaks of magnesium, aluminium and zinc, and silicon, carbon and oxygen from the silane film

Summary

Introduction

High strength-to-weight ratio of magnesium and its alloys have made them the widely investigated materials for applications where weight reduction is of utmost importance (e.g., automobiles, aircraft structures) [1], as well as the non-toxic nature of magnesium has attracted attention for use of magnesium alloys in bioimplant applications [2,3,4,5]. Standard reduction potential for pure magnesium is −2.37 V with respect to standard hydrogen electrode (SHE). This is the lowest for any metal/alloy used for structural applications. The high electronegativity of magnesium and its alloys greatly amplifies the importance of problem of corrosion as compared to that for other metals and alloys used in commercial applications [1,2,3,4]

Methods

Results

Conclusion