A Comparative Evaluation and a Benefit Assessment of Sintering α-Al2O3 in Induction and Conventional Furnaces

Abstract

This work provides a quantitative comparison of induction heating and conventional resistance-furnace sintering for the processing of high-purity α-Al₂O₃ ceramics, focusing on thermal behavior, energy efficiency, and sintering quality. The study combines experimental characterization of sintering samples and analysis of thermal curves. Here is also covered an energy-based modeling to propose a microstructural development, heating behavior, and overall energy demand for induction and conventional resistance furnaces. The materials used in this work are commercial alumina (as-received) and milled powder to isolate the effect of the heating method, with a mechanically milled condition. We also examined its influence on microstructure. The samples sintered by induction heating achieved a maximum relative density of ∼98.2% and a Vickers hardness of 2060 ± 22 HV at 1500°C for milled alumina powder, compared to 1980 ± 28 HV and 97.1% relative density for conventional sintering under identical conditions. Thermal simulations in a Matlab-based finite differences methods (FDM) model reveal that resistance-furnace heating is dominated by slow radiative and convective fluxes, leading to a slower achievement of a homogeneous temperature distribution, which in practice means the system takes longer to equilibrate. In induction heating, the sintering starts in the first few minutes and the pellet edges exhibit a more pronounced temperature rise. However, this condition diminishes rapidly, and within a short time the temperature distribution becomes homogeneous, achieving uniformity significantly faster than in a conventional furnace. Energy analysis shows that induction reduces total cumulative electrical consumption by 92.37% relative to the furnace at the highest target temperature evaluated (1500°C).