# The Preparation and Properties of Ti(Nb)-Si-C Coating on the Pre-Oxidized Ferritic Stainless Steel for Solid Oxide Fuel Cell Interconnect

## TL;DR

A new coating improves the performance and durability of solid oxide fuel cells by reducing oxidation and maintaining electrical properties.

## Contribution

A novel Ti(Nb)-Si-C coating is developed to enhance oxidation resistance and block chromium diffusion in ferritic stainless steel interconnects.

## Key findings

- The Ti(Nb)-Si-C coating significantly improves oxidation resistance with a low parabolic rate of 9.36 × 10−15 g²·cm⁻⁴·s⁻¹.
- A dual-layer oxide scale forms, with Cr₂O₃-rich inner layer and TiO₂/SiO₂-rich outer layer.
- The coating maintains good electrical properties with an ASR of 13.57 mΩ·cm² after 500 h at 800 °C.

## Abstract

Cr2O3 scale growth and volatilization are the main cause of the performance degradation of solid oxide fuel cells (SOFCs) with an Fe-based ferritic stainless steel (FSS) interconnect. In this work, an amorphous Ti(Nb)-Si-C coating is prepared on the pre-oxidized SUS430 with D.C. magnetron sputtering as the protective coating. The amorphous Ti(Nb)-Si-C coated alloy exhibits significantly enhanced oxidation resistance, and the oxidation kinetics obey the parabolic law with a low parabolic rate of 9.36 × 10−15 g2·cm−4·s−1. A dual-layer oxide scale is formed composed of an inner layer rich in Cr2O3 and an outer layer rich in rutile TiO2 and amorphous SiO2. MnCr2O4 appears at the interface between the inner and outer oxide layers. Meanwhile, the amorphous Ti(Nb)-Si-C coating also effectively blocks the outward diffusion of Cr. In addition, the coated steel presents good electrical properties with an area-specific resistance (ASR) of 13.57 mΩ·cm2 at 800 °C after oxidation at 800 °C in air for 500 h.