Characterizations of plasma sprayed CNT reinforced Al2O3 coatings on boiler tube steels

CNT reinforced Al₂O₃ coatings were obtained on boiler tube steels namely ASTM-SA213-T-11, ASTM-SA213- T-22 and ASTM-SA213- T-91 through air plasma spray process. Ni-Cr was also used as a bond coat before applying CNT- Al₂O₃ composite coatings. The coatings were subjected to metallography, XRD and SEM/EDAX analysis. The microhardness of the coatings has been measured along the cross-section. The studies made by authors revealed that CNT reinforced Zn and Ni coatings has exhibited higher resistance to corrosion when compared to pure Zn and Ni coatings respectively. CNTs act as inert physical barriers to the initiation and development of defect corrosion, modifying the microstructure and hence improving the corrosion resistance of the coating.