(312b) Multilayer Coatings That Utilize Both Superhydrophobicity and Corrosion Inhibition to Reduce Carbon Steel Corrosion

Internal corrosion is the second leading cause of natural gas transmission pipeline incidents in the United States, but there is no established method to prevent it. As a result, the internal surface of carbon steel pipelines must be periodically cleaned and inspected to remove rust and avoid leaks. A superhydrophobic coating can reduce carbon steel corrosion by minimizing contact with corrosive liquid. This is achieved by trapping air on its porous surface, essentially suspending the liquid above a series of tiny air pockets. However, this porous structure also allows water vapor to permeate through, causing corrosion underneath the superhydrophobic coating. In this work, water-resistant corrosion inhibitors are used in conjunction with superhydrophobicity to address this deficiency. Specifically, anti-corrosion coatings were made with (1) a top portion that minimizes contact with corrosive solution via superhydrophobicity, (2) a middle portion that acts as a primer, and (3) a bottom portion that uses corrosion inhibitors to handle permeated water vapor. Each portion can contain one or multiple layers that are deposited using a process known as layer-by-layer (LbL) assembly, which allows ingredients to be deposited at designated locations with nanometer precision. By fine-tuning the composition of each portion one layer at a time, the corrosion rate was reduced from 1.12 mm/year (bare carbon steel) to 0.06 mm/year in CO2-saturated salt water, which should be enough to extend the service life of natural gas pipeline to >100 years.