酸化ニッケル(NiO)添加α SiC焼結体の導電特性

概要

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Temperature dependence of electrical receptivity has been investigated for a SiC ceramics added with transition metal oxides in order to develop a heating element, whose electrical resistively is positive or constant against temperature up to 400℃ electrical receptivity of a SiC with no addition is 1×10^3Ω cm at room temperature, and decreases by raising the temperature. The a SiC samples added with Cr_2O_3, CoO or NiO at 5 wt% show a receptivity less than 5Ω cm at room temperature. Electrical receptivity of a SiC added with Cr_2O_3 or CoO at 5 wt% decreases by raising the temperature. On the other hand, the a SiC sample added with NiO at 5 wt% shows a constant receptivity in the temperature range from room temperature to 400℃. Electrical receptivity of the a SiC samples added with NiO at less than 3 wt%. is more than 10^2Ω・cm at room temperature, and decreases by raising the temperature. Electrical receptivity of the α-SiC samples added with NiO at more than 5 wt% is less than 5 Ω・cm at room temperature, and its temperature coefficient is constant or positive up to 400℃ The added NiO reacts with SiC to form Ni_3Si_2 at high temperature during the sintering process. The Ni_3Si_2 product remains at grain boundary with a metallic property of positive temperature coefficient, and compensates the negative property of the a SiC matrix resulting in the constant receptivity of α-SiC/NiO against temperature.
1994-02-01