Chemical Modification of Silane-Based Coating with Inhibitor for Anticorrosive Application

Abstract

A silane-based coating was prepared by sol–gel method using (3-glycidoxypropyl) trimethoxysilane and tetraethyl orthosilicate as precursor. Aluminium isopropoxide was used as a chemical modifier; the concentration was varied on molar basis as 0.2, 0.4 and 0.6 moles. With the addition of aluminium isopropoxide, hardness properties and anticorrosive properties were observed to be improved. The corrosion inhibitors were added to improve the performance further. Efficiency of the two corrosion inhibitors was compared, i.e. benzotriazole (BT) and 2-mercaptobenzothiazole (MBT), in the system where they get added to the silane backbone through their functional groups. MBT shows better anticorrosive properties over BT, which is evaluated by salt spray and electrochemical impedance spectroscopy. Improvement in hydrophobic nature is also observed with MBT in the system. Mechanical performance of the coating also improves with the addition of MBT as compared to BT. The presence of sulphur linkage in MBT as compared to the BT is the key component for the improvement in the performance.