Cathodic delamination of polyurethane/multiwalled carbon nanotube composite coatings from steel substrates

• Polyurethane composite coatings with different MWCNT contents were prepared.
• The microstructure of the coating with MWCNTs was studied.
• The stability of steel/coating interface to hydrolysis and corrosion was studied.
• The stability of the coating to cathodic delamination from the defect was studied.

Polyurethane composite coatings with different multiwalled carbon nanotube (MWCNT) contents were prepared on steel substrates to study the effect of MWCNT content on the cathodic delamination of the polyurethane composite coatings. The cathodic delamination of the polyurethane composite coatings was measured using a Scanning Kelvin Probe (SKP). An increase in MWCNT content to 0.5 wt% significantly reduced the cathodic delamination of the polyurethane composite coatings because the high density of MWCNTs blocked the transport pathways of water and oxygen molecules through the coating. It could be concluded that the incorporation of MWCNTs was a possible way to lessen the cathodic delamination of the polyurethane coatings.