SiC fiber with low electrical resistivity and oxygen content

Abstract

A new SiC fiber was prepared by the pyrolysis of polycarbosilane (PCS) fiber cured with unsaturated hydrocarbons. The fiber, with oxygen content of 4-6 wt%, offers high tensile strength of 2.5-2.8 GPa. The electrical resistivity of the fiber is only about 0.5 Ω·cm, much lower than general SiC fiber obtained from traditional air curing process. Degradation of mechanical property in argon and air at high temperature is retarded by 200-300°C with respect to the Nicalon NL-202 fiber. The low electrical resistivity of the fiber exhibits excellent thermal stability, it almost remains 0.4-0.8 Ω·cm after thermal exposure test from the room temperature to 1600°C in argon. The low electrical resistivity mainly attribute to an excess carbon layer which is about 50 nm in the circular outer part. polycarbonsilane, SiC fiber, electrical resistivity, excess carbon layer Citation:Wang D Y, Mao X H, Song Y C, et al. SiC fiber with low electrical resistivity and oxygen content.

Design, Preparation and Microwave-Absorbing Properties of Sandwich-Structure Radar-Absorbing Materials Reinforced by Glass and SiC Fibres

“…The resistivity of the SiC fibre fabrics (resistive sheet) was sensitive to the microstructure of the SiC fibre, and slight microstructural changes may greatly vary the resistivity of the SiC fibre fabrics [22]. From our previous studies [16,17,23], it may be inferred that a pyrocarbon layer exists on the surface of the KD-I SiC fibres. The special surface characteristics will affect the electrical properties of the SiC fibres markedly.…”

Preparation and characterization of near-stoichiometric silicon carbon fibres

“…According to previous studies, cyclohexyl group can be introduced into the PCS skeleton during CVC, and it may be converted to free carbon embedded in the Si-C networks in a subsequent pyrolysis process. 26,27 Considering the characteristics of the gas-solid reaction, cyclohexyl group will be incorporated to a greater extent on the surface, generating a thicker layer with excess carbon. In contrast, a carbon layer was also observed on the surface of Hi-Nicalon Type S, with its thickness being approximately 150 nm, 19 which might be associated with the high-temperature properties of SiC bres.…”

Preparation and Properties of Pinacolborane Modified Polycarbosilane as SiC Fiber Precursor

“…One effective solution is strengthening the bulk ceramics with continuous fibers [3,4]. Hence, the manufacturing of high-performance fibers is of particular interest and value [5,6], which accounts for the wide application of SiC fibers in aerospace [7][8][9][10]. Unfortunately, the strength of SiC fibers degenerates at ultrahigh temperature because of the oxidation or decomposition of SiC x O y [11][12][13].…”