Enhancement of ammonia corrosion resistance of coatings through improving dispersion and binding site of graphene oxide in silane coatings

Copper metal is essential to our production process, but it is highly corrosive in an ammonia environment and must be highly valued. Anti-corrosion coating is a simple and cost-effective method of preventing metal corrosion. In this study, a composite silane coating was prepared on copper using an impregnation method with mercaptopropyltriethoxysilane (TPTES) as the silane substrate and graphene oxide (GO) modified with isophorone diisocyanate (IPDI) or isocyanatopropyltriethoxysilane (IPTS) as filler to protect the copper from ammonia corrosion. The coating samples were hanging tested against ammonia corrosion by setting up two corrosive environments: ammonia gas and ammonia water. After 20 days of corrosion, the surfaces of the TPTES/IPDI-GO and TPTES/IPTS-GO coatings remained unchanged under both ammonia environments and the corrosion rate was consistently low at 2-3 μm/y. Additionally, the coating exhibited high protective qualities according to the electrochemical impedance spectroscopy (EIS) test in a 3.5% NaCl solution, which is attributed to the good dispersion that improves the densification and regularity of the coating. Meanwhile, IPTS-GO has a greater binding force with the coating matrix due to the increased number of reactive sites, resulting in further improved corrosion protection. This study provides an idea for research on ammonia-resistant coatings.