The influence of MnCo₂O₄, CoCr₂O₄, CoFe₂O₄ and Co₃O₄ spinels on the thickness of chromia scale during two types of oxidation tests

Most current research has concentrated on solid oxide fuel cells (SOFCs) to resolve the contact resistance and cathode-chromium-poisoning problems associated with application of ferritic stainless steels as interconnects. In this study AISI 430 ferritic stainless Steel was coated in a cobalt-base pack mixture by pack cementation method. Isothermal oxidation and cyclic oxidation were applied to evaluate the oxide layer thickness which was created during these tests. Results showed the formation of MnCo₂O₄, CoCr₂O₄, CoFe₂O₄ and Co₃O₄ spinels during oxidation improved oxidation resistance. The increase of oxidation time and cycle number enhanced the oxide thickness. Also the coated substrate oxide thickness was remarkably lower compared with uncoated ones in all tests.