Development of oxidation-resistant and electrically conductive coating of Ti–Al–C system for the lightweight interconnects of solid oxide fuel cells

Abstract

The paper studies oxidation resistance and electrical conductivity of dense coatings produced by vacuum-arc deposition technique on α-titanium thin (0.1 mm) substrate using a hot pressed Ti2AlC–TiC target. The coatings were deposited at low (7 mA/cm2) and high (15 mA/cm2) current densities on the substrate and marked LCD and HCD, respectively. This provided different local chemical and phase compositions of the coatings. It was found that phase compositions of the coatings differ from that of the target. The HCD coating has high oxidation resistance evaluated in terms of the specific weight gain (Δm/S = 0.06 mg/cm2) as well as high surface electrical conductivity (σ = 1.23·106 S/m) after long-term (1000 h) holding at 600 °C in the air due to the formation of an over thin (450 nm) Ti–Al-(C, O, N) near-surface layer. The thin titanium substrate with such Ti–Al–C coating is recommended as a lightweight interconnect of an intermediate-temperature solid oxide fuel cell.

Keywords

• Ti-Al-C coating
• Vacuum-arc deposition
• Nanostructure
• Oxidation resistance
• Electrical conductivity
• Lightweight fuel cell