Oxidation behavior and electrical properties of metal interconnects with Ce-doped Ni–Mn spinel coatings

Abstract

To improve the high-temperature oxidation resistance and electrical conductivity of ferritic stainless steels, protective Ce-doped NiMn2O4 spinel coatings were fabricated on the surface of SUS430 steel by electrophoretic deposition (EPD). The phase structure and microstructure of Ce-doped NiMn2O4 in both powder and coating forms were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The high-temperature oxidation of the NiMn2O4 spinel coating before and after Ce doping in the air at 800 °C for 168 h was studied by weight gain experiments. The area-specific resistance (ASR) of coatings was measured by a standard four-probe method. It was found that the Ce-doped NiMn2O4 spinel powder displayed a stable structure, high crystallinity, fine grain size, and decreased agglomeration when the Ce content was fixed at 0.05 mol∙L−1. The oxidation kinetics of NiMn2O4-coated SUS430 steel before and after Ce doping obeyed a parabolic law with parabolic rate constants of 4.58 × 10−15 g2 cm−4 s−1 and 1.83 × 10−15 g2 cm−4 s−1, respectively. When oxidized at 800 °C for 50 h, the ASR value of the coated samples before and after Ce doping stabilized at about 15.2 mΩ∙cm2 and 14.5 mΩ∙cm2, respectively. This work demonstrated that the Ce-doped NiMn2O4 spinel coating improved the high-temperature oxidation resistance and the electrical conductivity of metal interconnects.