Investigation of the Influence of Hydrofluoric Acid and Temperature on the Sintering Processes and Phase Formation in Alumina Nanofiber-based Ceramics

DOI:https://doi.org/10.48084/etasr.9547

This work studies a ceramic material, synthesized from alumina nanofiber via semi-dry pressing with an average diameter of 10 nm and a high aspect ratio (>1000), with Hydrofluoric Acid (HF) used as a mineralizer. The effects of varying firing temperature and HF concentration were systematically investigated. The material was characterized using electron microscopy, X-ray fluorescence analysis, and X-ray phase analysis, while thermodynamic calculations of phase transformations were conducted. Additionally, strength, density, and open porosity were analyzed as functions of the processing parameters. The analysis revealed that an optimal HF concentration of 1% and a firing temperature of 800 °C yield the best physical and mechanical properties. Furthermore, the transition mechanism from the γ-phase to the α-phase under varying HF concentrations and firing temperatures was examined. A linear dependence of the concentration of Fluorine (F) atoms in the ceramic material on the firing temperature was established. The maximum physical and mechanical characteristics include a compressive strength of 49 MPa with a porosity of 46% and a density of 1.47 g/cm³.