Effect of CNFs content on the tribological behaviour of spark plasma sintering ceramic–CNFs composites

Alumina-carbon nanofibres (CNFs) and silicon carbide–CNFs nanocomposites with different volume fraction of CNFs (0–100 vol.%) were obtained by spark plasma sintering. The effect of CNFs content on the tribological behaviour in dry sliding conditions on the ceramic–carbon nanocomposites has been investigated using the ball-on-disk technique against alumina balls. The wear rate of ceramic–CNFs nanocomposites decreases with CNFs increasing content. The friction coefficient of the Al2O3/CNFs and SiC/CNFs nanocomposites with high CNFs content was found to be significantly lower compared to monolithic Al2O3 and SiC due to the effect of CNFs and unexpectedly slightly lower than CNFs material. The main wear mechanism in the nanocomposite was abrasion of the ceramic and carbon components which act in the interface as a sort of lubricating media. The experimental results demonstrate that the addition of CNFs to the ceramic composites significantly reduces friction coefficient and wear rate, resulting in suitable materials for unlubricated tribological applications.