Effect of yttrium on the oxidation resistance and areaspecific resistance of MnCo2O4 coating

(MnCo)3-xYxO4 spinel coatings were prepared on AISI430 alloy by electrodepositing and sintering incompletely crystallized precursor powders. Yttrium significantly refined the grain of (MnCo)3O4 coatings and improved the high temperature oxidation resistance of the coating. The mass gain of (MnCo)2.85Y0.15O4 coatings was 0.53 mg·cm−2 as oxidized at 800 °C for 200 h, being only 26.0 % of that of AISI 430 and 56.4 % of that of (MnCo)3O4 coating. The Y content of (MnCo)3-xYxO4 coatings affected the crack formation on the coating surface in high temperature oxidation process. Doping of 0.1 at.% Y caused severe lattice distortion and enhanced internal stress, resulting in the nucleation and growth of cracks. However Y2O3 was formed along grain boundaries for 0.15 at.% Y, which released the internal stress and improved the bonding force. The failure behavior of the coating was revealed by establishing the relationship between the number of failure units and the internal stress of the coating. (MnCo)2.95Y0.05O4 coating exhibited a stable performance due to the minimum value and increase of ASR in high-temperature oxidation.