Electrical conductivity of gelcast alumina sintered under inert atmosphere

Electrically conductive alumina ceramic has been successfully fabricated by sintering of dried gelcast alumina in an inert atmosphere. The process was developed similar to the conventional gelcasting method except for varying the amount of monomer in the premix solution. The sintering treatment was carried out in argon gas from 1100 °C to 1700 °C. Van der Pauw's method was used to measure the electrical resistivity. The results showed that increasing monomer addition and sintering treatment were significantly affecting in lowering electrical resistance. Using the lowest monomer addition and increased sintering treatment, the measured electrical resistivities were in the range from 1.94 Ω-cm to 0.37 Ω-cm. The material exhibited ohmic behavior and rendered two regimes of Arrhenius profile in the plot of electrical conductivity against increasing temperature from 20 °C to 600 °C. All conduction processes were governed by the presence of carbon that caused the alumina grains in polygonal morphology typical of densification. Furthermore, physical tests were conducted to describe the electrical conduction behavior of the material.