Effect of Y2O3 addition on the oxidation resistance of TiN/Ni composites applied for intermediate temperature solid oxide fuel cell interconnects

Abstract

TiN/Ni Composites with high electrical conductivity and suitable thermal expansion coefficient have become potential materials for intermediate temperature solid oxide fuel cells interconnects (IT-SOFCs). The interconnect study is very broad in the current form, which is crucially important to increase fuel- cells power efficiency. In order to study the effect of Y2O3 addition on the oxidation resistance of TiN/Ni composites, composites with low Y2O3 content are fabricated by spark plasma sintering. The results show that by adding minor Y2O3, the average size of TiN particles increases from 1.65 μm to 2.92 μm. In addition, adding Y2O3 to the composite can reduce the mass gain (800 °C/120 h oxidation) from 4.46 mg·cm−2 to 2.97 mg·cm−2, which is a result of that Y2O3 promoted the formation of relatively dense NiO and inhibits the formation of loose rutile TiO2. Compared with TiN/Ni composites without Y2O3, the thermal expansion coefficient of Y2O3-containing composites is reduced from 12.4 × 10−6 k−1 to 11.9 × 10−6 k−1, and the diffusion depth of O is brought down from 98 μm to 63 μm. Meanwhile, composites with Y2O3 exhibits excellent electrical conductivity (1.34 × 104 S·cm−1), and high flexural strength (716 ± 14 MPa) after 800 °C/120 h oxidation. Therefore, Y2O3 can effectively change the composition and microstructure of the oxide scale and optimize the oxidation resistance of composites.