Tribological characteristics of short glass fibre reinforced polycarbonate composites

Abstract

Polymeric composite material products are manufactured by injection moulding and are valued for their good mechanical and tribological properties. Various filler reinforcements are frequently added to the base materials to improve the wear and impact properties. The present study analyses the wear behaviour of polycarbonate reinforced with 20 wt.% short glass fibres. The specimens were prepared under different moulding conditions, with varied filling time, melt temperature, and mould temperature. Friction and wear tests were performed with a Schwingum Reibung Verschleiss (SRV oscillation friction wear) ball-on-plane tester. The worn surface was examined with scanning electron microscopy. The results indicate that the wear volume loss in the sliding direction perpendicular to the melt flow direction is usually lower than that in the sliding direction parallel with the melt flow direction. The optimum injection moulding conditions for lowest wear volume loss are a filling time of 5 s, melt temperature of 290°C, and mould temperature of 80°C, when the sliding direction is parallel with the melt flow direction. The effects of wear volume loss are influenced significantly by the thickness of the frozen layer and the fibre orientation with respect to the sliding direction. The higher the wear volume loss, the higher is the friction coefficient. The wear volume loss in the sliding direction parallel with the melt flow direction is in good agreement with the distribution of the frozen layer thickness. Grooves, cracks, cutting of fibres and debonding of fibres are the major wear mechanisms found in wear tests of short glass fibre reinforced polycarbonate.