Abstract
The residual stresses in manganese cobaltite, i.e., Mn1.5Co1.5O4, coatings applied onto alloys 441 and Crofer 22 APU were determined by X-Ray Diffraction. The residual stresses were found to be tensile at 800�C for both systems. The residual stress for spinel-coated AL441 relaxed with time and reached a value of 0.16�0.02 GPa after 300 minutes. The stress relaxation process was slower for spinel-coated Crofer and reached a value of 0.23�0.01 GPa after 500 minutes.
Four-point bend SENB testing technique was used to evaluate the toughness of the interfaces between LSM10, i.e., (La0.9Sr0.1)0.98MnO3+δ, and spinel-coated AL441 and Crofer. Sandwich test specimens were prepared by sintering the LSM10 layer at 900�C for four hours in air or under PO2 cyclic conditions. The strain energy release rate was found to be 1.52�0.11 J/m2 for regular sintering and 1.47 � 0.15 J/m2 for sintering with cyclic PO2 treatment. This difference was found to be statistically insignificant.
