Cu-Fe substituted Mn-Co spinels by High Energy Ball Milling for interconnect coatings: insight on sintering properties

Corrosion effects on metallic interconnects of Solid Oxide Fuel Cells (SOFC), including the growth of insulating scales and chromium evaporation, can be reduced through the deposition of protective coatings. Mn-Co oxide coatings obtained by wet chemical coating techniques are competitive on large-scale manufacture due to low costs and high producing volumes. These methods however require the formulation of powders and inks as well as high temperature sintering treatments for reducing residual porosity being one of the main drawbacks. Metal doping of the traditional Co-Mn composition has been suggested as an option to improve the sintering behaviour and the final coating properties. In this work, a simple High Energy Ball Milling (HEBM) process of metal oxides is exploited to produce Cu and Fe substituted Mn-Co spinel nanostructured precursors. Among the powder production techniques, HEBM is an environmentally friendly and low cost mechano-chemical processing methodology, which exploits hitting balls as energy transfer media. The HEBM treatment produces a very fine grinding and intimate mixing of particles, which leads to particle activation, nucleation of stable or metastable phases, amorphisation processes, or chemical reactions. The high temperature behaviour of the produced powders has been studied by means of thermogravimetric and dilatometric analyses, while investigating morphological and structural properties of the processed powders and pellets, in order to evaluate the role of the additives in the sintering behaviour.