Fibre coatings for the fabrication of graphite-reinforced magnesium composites

A new fabrication technique for graphite-fibre-reinforced magnesium is presented. An air-stable silicon dioxide coating is deposited on the fibre surfaces from an organometallic precursor solution. The fibres are passed through this solution, followed by hydrolysis or pyrolysis of the organometallic compound to form silicon dioxide on the fibre surfaces. The silicon dioxide coating facilitates wetting and bonding when the fibres are immersed in molten magnesium. A modification of this coating technique was developed for coating fibres with amorphous carbon, which was found to improve the adhesion between the graphite fibres and the silicon dioxide coating. Composites containing either T300, P55, or P100 graphite fibres in pure magnesium, magnesium-1 wt% silicon, and magnesium alloy AZ91 have been fabricated. Preliminary mechanical property data are presented.