Alternating-current electrical behavior of carbon fiber tows exhibiting inductive reactance and resistance-dominant impedance

This work addresses the alternating-current (AC) electrical behavior (1-100 kHz) of continuous PAN-based carbon fiber tows. Resistance-dominant impedance Z and inductance-dominant reactance X occur. The resistance (R) dominance of Z is diminished by decreasing R through either coating the fiber with nickel or increasing the number of fibers per tow. Without coating, Z is slightly above R ; with coating, Z is much above R . The θ is < 45°, being higher with the nickel coating. It increases with the number of fibers per tow. The θ , X (totally inductive) and Q increase with increasing frequency. The θ decreases slightly as the distance increases. Decreasing the number of fibers per tow is more effective than nickel coating for enhancing L . The L decreases with increasing number of fibers per tow, due to partial compliance with the inductors-in-parallel model. The limited compliance is because the fiber-fiber contacts enhance L . The fractional contribution of the fiber-fiber contacts to L tends to exceed 90%, increasing with increasing number of fibers in the tow. A small number of fibers per tow is recommended for providing relatively high L . The fiber-fiber contacts do not affect the tow resistivity, but greatly enhance L , which does not comply with the inductors-in-series and inductors-in-parallel models. Nickel coating and increasing the number of fibers per tow are effective approaches for decreasing R , thereby increasing Q and θ . The coating strengthens the frequency dependence of θ and Q . Short-circuited inductive discharge does not occur for tows, but occurs for a single fiber.