Oxidation behavior and electrical conductivity of MAXs phase (Ti,Nb)3SiC2 as a novel intermediate-temperature solid oxide fuel cell interconnect material in anode environment

Abstract

(Ti,Nb)3SiC2 possesses high oxidation resistance and electrical conductivity in cathode side, endowing it potential application as intermediate-temperature solid oxide fuel cell (IT-SOFC) interconnects. However, the performances of (Ti,Nb)3SiC2 in anode side must be well understood before the application comes true. In this paper, the oxidation resistance and electrical conductivity of (Ti,Nb)3SiC2 in simulated anode reducing atmosphere are systematically investigated. The oxidation kinetics follows parabolic law with a kP value of 7.57 × 10−14 g2 cm−4 s−1. The formed single oxide layer is composed of uniformly distributed Nb-doped rutile TiO2 and amorphous SiO2, without carbon deposition. High partial pressure of H2 and CO in simulated anode reducing atmosphere inhibit the oxidation by H2O and CO2. Nb doping with strengthen the Ti–O bond can also slow down the oxidation rate. ASR of (Ti,Nb)3SiC2 after 605 h cyclic oxidation is 1.6 and 3.7 mΩ cm2 at 800 °C and 500 °C, respectively. The low ASR comes from the induced extra electrons by Nb doping and the dissolution of H2O and H2 in oxide, and the integrated TiO2 conductive network in the scale. (Ti,Nb)3SiC2 exhibits superior performances in simulated anode reducing atmosphere, making it an promising candidate for SOFC interconnect.