Oxidation Behavior and Conductivity of UNS 430 Stainless Steel and Crofer 22 APU with Spinel Coatings

Coatings of Cu-Mn, Co-Mn, and Cu-Fe spinels were obtained on UNS 430 and Crofer 22 APU ferritic stainless steel by oxidation of electroplated metal coatings. The thickness of the spinel coatings was 20-30 um. The average weight gain of Crofer 22 APU with Cu-Mn, Co-Mn, and Cu-Fe spinel coatings after 1400 hours oxidation at 750{degree sign}C was 0.00052 g/cm2, 0.00022 g/cm2, and 0.00027 g/cm2, whereas the average weight gain of UNS 430 stainless steel with Cu-Mn, Co-Mn, and Cu-Fe spinel coatings was respectively 0.0003 g/cm2, 0.0001 g/cm2, and 0.00021 g/cm2. The area specific resistance of both Cu-Mn and Co-Mn spinel coated alloys was 0.003 Ω•cm2 after oxidation at 750åC for 1500 hours. Compared with an ASR of 0.189 Ω•cm2 for uncoated UNS 430, it is clear that the coatings can effectively provide a conductive path to the metallic substrate.