Performance evaluation of mercapto functional hybrid silica sol–gel coating on copper surface

• Mercapto functional silica (MFS) sol–gel coatings were used to protect copper.
• The influence of TEOS on MFS coatings' properties was investigated.
• TEOS has a great influence protection performance of MFS coatings for copper.
• TEOS can enhance the scratching resistance of MFS coatings.
• MFS coatings can provide good protection performance for copper.

Mercapto functional silica (MFS) sol–gel coatings were prepared by hydrolysis and condensation of 3-mercaptopropyltrimethoxysilane (MPMS) and tetraethylorthosilicate (TEOS) at different molar ratios. These MFS coatings were used to protect copper and their properties on copper surface were studied by various complementary techniques. Results demonstrated that MFS coatings possessed excellent thermal stability below 300 °C, high resistance to scratch and good protection performance for copper. The best corrosion protection was obtained when the molar ratio of MPMS:TEOS is 2:1. TEOS had two opposite effects on the protection performance of MFS coatings. On the one hand it enhanced barrier effect of MFS coating through improving crosslinking density of the coating; on the other hand it reduced barrier effect by causing coating defects.