Synergistic effect of CeO2 and Al2O3 nanoparticle dispersion on the oxidation behavior of MCrAlY coatings deposited by HVOF

In this study, the as-received and nano-scaled oxide dispersion strengthened (ODS) MCrAlY coatings were deposited using high-velocity oxy-fuel (HVOF) spraying process. The high-energy planetary ball-milling process was utilized to prepare CeO2 and Al2O3 nanoparticles. ODS-NiCoCrAlY feedstock powders were also developed using the ball-milling process. The various formulations of Al2O3 and CeO2 nanoparticles (0.5 and 1.0 wt%) were chosen to apply different types of ODS-NiCoCrAlY coatings. The microstructure of the as-received and ODS coatings were evaluated by field emission scanning electron microscope (FESEM) as well as the commercial and ODS powders. Furthermore, the microhardness of different compositions of ODS coatings was accordingly investigated and the obtained results were compared with as-received coating. On account of the measurement of oxidation kinetics, the freestanding as-received and ODS coatings were exposed to air at 1000 °C up to 500 h and the thickness growth rate of the α-Al2O3 oxide layer was simultaneously examined. The results exemplified that NiCoCrAlY+1.0 wt% nano-CeO2+0.5 wt% nano-Al2O3 coating had a better oxidation resistance and lower oxide scale growth rate under the synergistic effects of both CeO2 and Al2O3 nanoparticles.