Investigation on the properties of Nb and Al doped Ti3SiC2 as a new interconnect material for IT-SOFC

A modified layered ternary compound (Ti0.98Nb0.02)3(Si0.95Al0.05)C2 was evaluated as a new interconnect material for intermediate temperature solid oxide fuel cells (IT-SOFC). The results indicated that the compound has low density (4.50 g/cm3), closer matched thermal expansion coefficient with Y2O3 stabled ZrO2 (9.0 × 10−6/K), low room temperature electrical resistivity (24 μΩ cm), and good mechanical properties and machinability. During the isothermal oxidation at 600 °C–800 °C, a monolithic layer with the mixture of rutile TiO2 and amorphous SiO2 formed on (Ti0.98Nb0.02)3(Si0.95Al0.05)C2. Its oxidation kinetics roughly follows a parabolic law, the rate constant is 0.45, 1.26, 1.57 × 10−7 mg2/cm4 s at 600 °C, 700 °C, 800 °C, respectively. After the oxidation at 700 °C and 800 °C in air for 100 h, its area special resistance is 5 and 12 mΩ cm2 at the corresponding oxidation temperature, respectively. In oxidizing environment, (Ti0.98Nb0.02)3(Si0.95Al0.05)C2 is very stable, and has not Cr or other element volatilization. All above determined properties of (Ti0.98Nb0.02)3(Si0.95Al0.05)C2 are favorable for its application as interconnect in IT-SOFC.