Mechanical properties of La1-xSrxCo0.2Fe0.8O3 mixed-conducting perovskitesmade by the combustion synthesis technique

This paper examined the room-temperature mechanical properties of a mixed-c onducting perovskite La1-xSrxCo0.2Fe0.8O3 (x = 0.2-0.8), Powders were made by the combustion synthesis technique and sintered at 1250 degrees C in air , Sintered density, crystal phase, and grain size were characterized. Young 's and shear moduli, microhardness, indentation fracture toughness, and bia xial flexure strength were determined. The Young's and shear moduli slightl y increased with increasing strontium content. Young's modulus of 151-188 G Pa and shear modulus of 57-75 GPa were measured, Biaxial flexure strength o f similar to 160 MPa was measured for lower strontium content batches. Stre ngth greatly decreased to similar to 40 MPa at higher strontium concentrati ons (x = 0.6-0.8) because of the formation of extensive cracking, Indentati on toughness showed a higher value (similar to 1.5 MPa.m(1/2)) for low stro ntium (x = 0.2) content and a lower value (similar to 1.1 MPa.m(1/2)) for t he other batches (x = 0.4-0.8), Materials with fine and coarse grain size w ere also tested at various indent loads and showed no dependence of toughne ss on crack size. In addition, fractography was used to characterize the cr itical flaw and fracture mode.