Synthesis, oxidation behavior and electrical properties of Ti(Nb)-Si-C coating for SOFC metallic interconnect
Xichao Li, Shouli Wei, Xianwei Sun, Jingxiang Zhao, Qiangqiang Hou, Kang Fu, Zuoqiang Dai, Lili Zheng
Abstract
• The dense amorphous Ti(Nb)-Si-C coating is obtained by magnetron sputtering. • The Ti(Nb)-Si-C coating greatly enhanced the oxidation resistance of SUS 430 alloy. • The Ti(Nb)O 2 + SiO 2 mixture oxide scale is formed on the surface of coating. • Outward diffusion of Cr is effectively mitigated by the coating during oxidation. • The coated sample exhibits good electrical property with the ASR of 12.78 mΩ•cm 2 . 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 ( k p = 1.1 × 10 -14 g 2 ·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·cm 2 after oxidation at 800 °C in air for 500 h.