Microwave-enhanced densification of sol–gel alumina films

Alumina films prepared by the sol–gel method were sintered at 1160 °C and 1200 °C using a 2.45 GHz microwave/conventional hybrid furnace in order to study the influence of microwave power on the sintering process and resultant samples. Experiments were designed to ensure that each series of samples underwent an identical thermal history in terms of temperature/time profiles. Sintering was carried out using three different heating approaches: pure conventional heating and hybrid heating with 600 W and 1000 W of microwave radiation, respectively. The results obtained showed that, compared with pure conventional heating, the presence of the microwave field led to higher sintered densities and crystallinity in the samples, indicating that the microwave field enhanced the sintering of the sol–gel alumina films and supporting the existence of the microwave effect.