Mechanistic Insight into Etching Chemistry and HF-Assisted Etching of MgO-Al₂O₃-SiO₂ Glass-Ceramic

The present study focuses on the etching conditions and mechanism of MgO-Al₂O₃-SiO₂ glass-ceramic (MAS) in hydrofluoric acid (HF). The results show that the amorphous phase has 218 times higher etching rate than pure cordierite crystal at room temperature. In addition, the activation energies of cordierite and amorphous phases in the HF solution are 52.5 and 30.6 kJ/mol, respectively. The time (tad) taken for complete dissolution of the amorphous phase depends on the HF concentration (CHF). Based on the etching experiments, a new model is established and refined to assess the tad evolution. In addition, a highly crystalline cordierite phase, with the high specific surface area (59.4 m²·g-1) and mesoporous structure, has been obtained by HF etching. This paper presents novel insights into the etching chemistry and opens up avenues for further research in the area of cordierite-based catalytic ceramics.