A new sinter-forging process based on a 915 MHz solid-state microwave source for sintering of oxides ceramics

This study presents the development of a fully instrumented sinter-forging process using a 915 MHz solid-state microwave source for the rapid and controlled sintering of dense oxide ceramics. Compared to conventional magnetron-based systems, the solid-state microwave source enables precise frequency tuning for optimal impedance matching and resonance conditions. Modeling and experimental characterization of the microwave applicator have enabled us to position the sample correctly in the cavity, ensuring efficient energy transfer and homogeneous heating. Sintering experiments carried out on alumina powder, both with and without applied pressure, revealed that the pressure-assisted process significantly improved densification, yielding near-complete density and increased hardness (21.6 GPa), while maintaining fine microstructures. This method highlights the potential of microwave-assisted sinter-forging for producing advanced ceramics with improved properties.