Effect of Carbon Black Particle Size and Sintering Temperature on Resistivity of Carbon Ceramic Linear Resistance

A carbon ceramic linear resistor is an important component of a high-voltage circuit breaker. It converts the L-C oscillating electrical energy in the power grid into thermal energy and suppresses the closing of the overvoltage. It is widely used in power systems applications. The dispersion of conductive materials and the composition of the conductive networks determine the performance of carbon ceramic resistors. This study explores the influence characteristics and mechanisms of carbon black particle size (50 nm, 10 μm) and sintering temperature (1250 ℃, 1300 ℃, 1400 ℃, 1500 ℃) on resistivity. The experimental results showed that when the particle size of carbon black was relatively small compared to the aggregate, the more carbon black there was of the same mass, the more conducive it was to the formation of a conductive network. However, when the particle size is too small, it is prone to agglomeration during sintering, which increases the resistivity. The sintering temperature affects the phase composition and microstructure of the resistor. Between 1250 and 1400 ℃, the mullite phase was formed and gradually grew. With an increase in the sintering temperature, the resistivity first decreased and then increased significantly. At 1400 ℃, the resistivity is 1.38 Ω m. This study reveals the correlation between the microstructure and conduction mechanism, providing a theoretical basis for the performance optimization of carbon ceramic linear resistors.