Hybrid Sol-Gel Poly(N-Ethylaniline) coatings with microcapsules with increased self-healing properties

Hybrid sol-gel coatings have the ability to actively replace hexavalent chromium compounds that are commonly used for aircraft coatings. Sol-gel coatings alone have become a large research topic due to their ability to be very corrosion resistant, but many are too brittle to be used as coatings in the aerospace industry. By combining a sol-gel compound with a conductive organic polymer, the resulting coating has a higher flexibility and a higher corrosion resistant ability. Combining the hybrid sol-gel coating with microcapsules filled with poly(dimethylsiloxane), the corrosion resistance of the protected substrate is increased. The coatings and microcapsules were characterized using FTIR, NMR, SEM and TGA. Three coatings were exposed to three different environmental conditions. A hybrid poly(N-ethylaniline) sol-gel coating with microcapsules, and sol-gel with microcapsules and a hybrid sol-gel coating were subjected over 28 days to a salt-spray chamber at room temperature and varied temperature testing varying between 5 and 50°C. The chambers followed the ASTM B117 standard for operating a salt spray apparatus. Additional testing was completed on the effect of humidity on coating integrity using ASTM D2247 standard for testing water resistance of coatings in 100% humidity. By monitoring the corrosion of the samples using EIS and SEM, the coatings with microcapsules showed an increase in corrosion resistance once during the 28 days, while the hybrid sol-gel coating showed steady degradation