Synthesis, oxidation behavior and electrical properties of Ti(Nb)-Si-C coating for SOFC metallic interconnect

Cr poison is the main cause of rapid performance degradation of solid oxide fuel cell (SOFC) stack from Cr-based ferritic stainless steel (FSS). Surface coating is an effective method to inhibit outward diffusion of Cr, contributing to reducing volatilization of Cr-containing compounds. In this work, Ti(Nb)-Si-C protective coating is prepared on surface of SUS 430 by DC magnetron sputtering with a dense and uniform structure. The coated samples possess greatly enhanced oxidation resistance (kp = 1.1 × 10–14 g2·cm-4·s-1) compared to bare alloy. Moreover, Ti- and Si-rich and Cr depleted outer oxide layer formed on the top surface of the alloy, which contributes to reducing the outward diffusion and volatilization of Cr. In addition, the thin oxide layers on surface of the coated alloy exhibit excellent electrical properties with an ASR value of 12.8 mΩ·cm2 after oxidation at 800 °C in air for 500 h.