MECHANICAL-PROPERTIES OF MAGNESIA-DOPED LANTHANUM CHROMITE VERSUS TEMPERATURE

Magnesia-doped lanthanum chromite is a potential material for use in s olid oxide fuel cells as an interconnector due to its resistance to ox idation and reduction. The strength and toughness of La(Cr0.9Mg0.1)O-3 were measured from 25 degrees to 1000 degrees C in the as-fired reduc ed state and after oxidation. The as-fired samples showed a peak in to ughness of approximately 3.9 MPa . m(1/2) at 125 degrees C which decre ased to approximately 1.4 MPa . m(1/2) at 600 degrees C and 2.8 MPa . m(1/2) at room temperature. This peak in toughness is hypothesized to be due to the rhombohedral-to-orthorhombic phase transition by a tough ening mechanism that is currently being investigated. The strength was also affected by the phase transition for both the as-fired reduced a nd the oxidized samples.