Effect of Y2O3 on the corrosion resistance of two-step sintered Al5Y3O12-MgAl2O4 sidewalls in the aluminum electrolyte

Magnesium-aluminum spinel (MAS) precursor powder was synthesized through a microwave hydrothermal method. The synergistic effects of sintering process and sintering aids on the densification, hardness and corrosion resistance of MAS were revealed. X-ray diffraction analysis (XRD), Archimedes' drainage method, fully automatic micro-Vickers hardness test and scanning electron microscopy (SEM) were performed to analyze the phase composition, bulk density, hardness microstructure and corrosion depth of the samples, respectively. Results revealed that the best two-step sintering condition is 1650 degrees C/3 min/1550 degrees C/20 h. The MAS products obtained under the best condition have clear grain boundaries, uniform particle size distribution, and few pores. When the amount of Y2O3 added is 4 wt.%, Y2O3 and Al2O3 form the second-phase solid solution Al5Y3O12, which activates the crystal lattice and benefits the sintering densification of MAS. Under these conditions, the relative density of the MAS composite ceramics prepared is relatively large (95.94 %), the grain size is relatively uniform, the hardness is relatively large (1264 HV), and the corrosion depth is relatively small (94.58 mu m).

Automated summary

Magnesium-aluminum spinel (MAS) precursor powder was synthesized through a microwave hydrothermal method. The study revealed the synergistic effects of sintering process and sintering aids on the densification, hardness, and corrosion resistance of MAS. Under the best sintering conditions, the prepared MAS composite ceramics demonstrated high relative density, uniform grain size, high hardness, and low corrosion depth.