Dominant parameters and mechanisms influencing the electrochemical shear-thickening polishing of 4H-SiC

Electrochemical shear-thickening polishing (ESTP) represents an innovative and highly efficient polishing method that combines the synergistic effects of anodic oxidation with shear-thickening polishing to significantly enhance workpiece polishing performance without inducing damage. To further enhance the material removal rate (MRR) and surface roughness (Sa) of 4H-SiC processed by ESTP, the effects of abrasive parameters on the rheological properties of the shear-thickening slurry were studied using rheological curves. Additionally, the influence and acting mechanisms of key process parameters on the MRR and Sa were examined and the improvements achieved by combining electrochemical anodizing with conventional shear-thickening polishing (STP) were evaluated through orthogonal experiments. The optimal ESTP process parameters were determined through process optimization, at which Sa was significantly reduced from 20.3 nm to 1.4 nm with an MRR of 321.7 nm/min after 30 min of polishing. Furthermore, surface and subsurface damage removal was confirmed through microstructural observations before and after polishing, demonstrating the effectiveness of the optimized ESTP process. Finally, the material deformation behaviors of the workpieces were investigated using indentation and scratch tests to verify the impact of anodization on their mechanical and polishing properties, demonstrating the superiority of ESTP over STP. The results of this study provide a theoretical foundation for future research on efficient, ultraprecise, and free-damage polishing techniques.