Preparation and characterization of lithium disilicate glass-ceramics derived from sol-gel route with varied agitation speeds

Lithium disilicate (LD) glass-ceramics were fabricated through conventional sol-gel and pressureless sintering methods, with the influence of stirring speeds (200, 400, 600 and 1000 rpm) on their microstructural evolution, phase formation, and mechanical properties being systematically investigated. The variation in agitation speed significantly affected the agglomerated sizes and morphological characteristics of the gel-derived LD powers, which in true induced noticeable differences in phase compositions and crystallinities of both the precursor powers and the final glass-ceramics. These morphological variations directly correlated with the archived relative densities of the sintered LD glass-ceramics, and the mechanical property variations were also linked with the differing aspect ratios of the precipitated LD crystals within the microstructures. Optimal performance was obtained at the stirring speed of 400 rpm, yielding glass-ceramics with exceptional properties: highest relative density (94.01 ± 0.16 %), flexural strength (182.72 ± 1.5 MPa), hardness (3.84 ± 0.20 GPa), and fracture toughness (3.07 ± 0.17 MPa·m^1/2). These finding demonstrated that mechanical stirring parameters profoundly influenced the characteristics of gel-derived LD powders and resultant glass-ceramics, suggesting potential applicability of this process control strategy to other gel-derived lithium silicate materials, including Li₂SiO₃ and Li₄SiO₄.