Low-temperature sintering of high-alumina ceramics assisted by recycled PV glass waste: Densification, sintering behavior, mechanical, dielectric properties and microstructural characteristics

This study investigated influences of recycled photovoltaic (PV) glass waste to sintering behavior, microstructural development, and multifunctional characteristics of high alumina ceramics at a lower temperature of about 1400°C. Cold and hot pressing were used to create four compositions with 5-20 wt% PV glass, which were then pre-sintered for 30 min at 1000°C under 5 MPa and finally sintered for about 2-6 h at 1400°C. When PV glass was added to the powder system (PST), liquid-phase sintering was greatly improved. This led to densification, increased linear shrinkage (∼2.3%), and a high bulk density of up to ∼3.73 g cm⁻ 3 , along with decreased porosity and water absorption. With a flexural strength of about 381 MPa, fracture toughness (Kᵢc) of about 4.6 MPa·m 3/2 and Vickers hardness of about 1375 HV1, the optimal composition (15 wt% PV glass) demonstrated superior mechanical performance. The dielectric characteristics were stable between 5 and 15 wt% PV glass, with a low dielectric loss (tan δ < 7 × 10⁻ 3 ) and a relative permittivity (ε′ ≈ 9.8-10.3). However, due to excessive amorphous phase formation, a slight degradation in dielectric reliability was noted at 20 wt% PV glass. With an ideal composition window of 10-15 wt%, the results show that recycled PV glass efficiently functions as a liquid-phase sintering aid, enabling high densification and balanced mechanical-dielectric performance at lower temperatures.