Oxidation resistance optimization of TiC/hastelloy composites by adding Ta element applied for intermediate temperature solid oxide fuel cell interconnects

Excellent oxidation resistance is one crucial requirement for intermediate-temperature solid oxide fuel cell interconnects. Composites with proper coefficient of thermal expansion and good electrical conductivity have been proposed as promising intermediate-temperature solid oxide fuel cell interconnects, whereas the oxidation resistance of them is still need to be improved. In the paper, the TiC/hastelloy composites with minor Ta element are prepared by in-situ reactive infiltration method, and the mass gain decreases from 1.18 mg cm−2 to 0.48 mg cm−2 (800 °C/100 h) by adding minor Ta, which is the lowest among existing composite interconnects. The oxide scale composed of Ni/Ti/Cr oxides with sandwich structure is formed on the composites. Compared with TiC/hastelloy composites without Ta element, Ta effectively prevents the inward diffusion of oxygen during oxidation by reducing oxygen vacancy concentration in TiO2 layer, and the inner oxide layer (O diffusion layer) vanishes, leading to the oxidation resistance optimization of composites. Meanwhile, the composites with Ta show linear suitable thermal expansion, 11.6 × 10−6 °C−1, and high electrical conductivity, 5500 S cm−1. Therefore, the addition of minor Ta element is one effective method to optimize the oxidation resistance of TiC/hastelloy composites.