Polymer-derived SiC/C/Al environmental barrier coatings on carbon steel

Carbon steel is a widely used structural material; however, it lacks corrosion resistance in water environments. An alternative approach to overcome this challenge is to implement the deposition of inherently corrosion-resistant ceramic coatings. SiC/C/Al coatings were developed at 700°C, using polycarbosilane in combination with Al and C, which were included as active and passive fillers, respectively. This work shows that it is necessary to use Al particle sizes below 10 µm for them to function as an active filler below 900°C. Owing to their laminar microstructure, these coatings showed a cohesive delamination with an adhesion strength of 10 MPa. Results demonstrated that these coatings were able to reduce the corrosion of carbon steel in saline water by 99.7%, with corrosion rates of 38.33 mpy for carbon steel, and 0.099 and 0.155 mpy for SiC/C and SiC/C/Al (10 µm) coatings, respectively.