Mechanical Properties of SOFC Anode Support Materials at Operating Conditions

The mechanical properties of solid-oxide fuel cells (SOFCs) and the materials they are fabricated from play an important role in manufacturability, durability and lifetime of the devices. Functioning cells must maintain a gas-tight seal though the cell, with no cracks or pores from anode or cathode, through a range of temperatures and oxygen partial pressures. The cell must be able to withstand intrinsic stresses in addition to those introduced by the stacking and sealing of the cells. It is known that the environmental conditions can affect the mechanical properties of materials. It has been shown that point defect concentration and temperature change the elastic modulus and strength of fluorite-structured oxides, but these tests were done using quenched samples or at high temperature in air, not at operating conditions. In this work the flexural modulus and strength of SOFC support materials are investigated under varying oxygen partial pressures at elevated temperatures, under the same conditions SOFCs experience during operation. This is achieved by using a three-point bend fixture on a universal testing machine, with a chamber and furnace to control the environmental conditions. From this information, relationships are built relating materials’ modulus and strength to the defect concentrations and temperatures that it would experience during operation.