Acoustic emission characteristics and CT-Based mesoscopic features of damage evolution in cathode carbon blocks under varying electrolysis durations

This study investigated the damage characteristics of graphitised cathode carbon blocks under different electrolysis durations (0 h, 1 h, 2 h, and 3 h). By integrating high-temperature mechanical loading, acoustic emission (AE) monitoring, and three-dimensional (3D) X-ray micro-computed tomography (micro-CT), the mechanical response, AE signal evolution, and microstructural porosity changes of the blocks were systematically examined. The results demonstrated that prolonged electrolysis significantly reduced the peak compressive strength of the cathode blocks. The number of AE events decreased with increasing electrolysis duration, declining from 1,571 in the control group to 299 in the 3-hour group, representing an 80.97% reduction. Distinct variation trends were observed in both b-values and S-values, while the RA-AF distribution indicated that electrolysis reduced the proportion of shear cracks from 70.53% to 20.07%. Micro-CT analysis revealed that after 3 hours of electrolysis, the total porosity decreased from 13.84% to 8.16%, and the proportion of interconnected pores decreased from 87.65% to 82.13%. Meanwhile, the electrolyte permeability increased from 17.26% to 49.32%. Similar changes were observed in the contact area. These findings elucidate the damage evolution of graphitised cathode carbon blocks during electrolysis and provide a basis for online condition monitoring and service life prediction.