Effect of TiC particles size on the oxidation resistance of TiC/hastelloy composites applied for intermediate temperature solid oxide fuel cell interconnects

Abstract

TiC/hastelloy composites are proposed as promising intermediate temperature solid oxide fuel cell (IT-SOFC) interconnects, and the oxidation resistance optimization of composites is crucial for the operation stability of IT-SOFC. Interparticles distance of TiC particles, determined by TiC content and particle size (dTiC), is found to significantly influence the oxidation resistance of composites. For composites with certain content of TiC, as dTiC decreases from 7.22 to 4.40 μm, mass gain (800 °C/100h) increases from 2.54 to 4.02 mg cm−2, while dTiC decreases from 3.10 to 2.21 μm, mass gain reduces from 2.44 to 1.05 mg cm−2. The opposite variation trend is resulted from the different microstructure evolution process of oxide scale as a function of dTiC. Critical d0 is speculated to exist for composites with a given TiC content, and dense TiO2-Cr2O3 layer begins to form on it. To improve the oxidation resistance of TiC/hastelloy composites, dTiC should be much greater (or smaller) than d0 to facilitate the formation of dense NiO (or TiO2-Cr2O3) layer in oxide scale.