Preparation and characterization of silicon nitride (Si-N)-coated carbon fibers and their effects on thermal properties in composites

This study investigates the effect of silicon nitride (Si-N)-coated carbon fibers on the thermal conductivity of carbon-fiber-reinforced epoxy composite. The surface properties of the Si-N-coated carbon fibers (SiNCFs) were observe using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy, and the thermal stability was analyzed using thermogravimetric analysis. SiNCFs were fabricated through the wet thermal treatment of carbon fibers (Step 1: silane finishing of the carbon fibers; Step 2: high-temperature thermal treatment in a N-2/NH3 environment). As a result, the Si-N belt was exhibited by SEM. The average thickness of the belt were 450-500 nm. The composition of Si-N was the mixture of Si-N, Si-O, and C-Si-N as confirmed by XPS. Thermal residue of the SiNCFs in air was enhanced from 3% to 50%. Thermal conductivity of the composites increased from 0.35 to 0.59 W/mK after Si-N coating on carbon surfaces. (C) 2015 Elsevier B.V. All rights reserved.