Crashed to powder recycled MgO-C bricks were exposed to burning residual carbon. The carbon-free MgO powder was utilized to produce composite anodes with the addition of 316L stainless steel with volumetric ratio 40:60, and 80:20 respectively. Mixed were granulated and pre-sintered at 1350 °C forming an equivalent of a coarse grain of composite material. Granules, mixed with steel powder and MgO powder with corresponding volumetric ratio, and with help of aids were extruded in a form of electrodes of a diameter of 20mm as well as cold isostatically pressed.
All produced anodes were subjected to sintering at 1350 °C followed by pre-oxidation step under different temperatures – 800 °C, 900 °C, and 1000 °C. Mechanical properties, oxidation/corrosion behavior, electrical conductivity, as well as presented phases of the manufactured specimens were characterized.
The work shows that upcycling of MgO-C bricks is an opportunity for the production of industrially-applicable refractory parts. Additional granules pre-sintering step enabled lower shrinkage of the material during the sintering of the anodes. Steel ceramic composite materials form surface phases that significantly increase resistance to cryolite/aluminium environment during pre-oxidation thermal treatment.