Tribological behaviour of carbon-fibre-reinforced SiC matrix composites

Reinforcement of monolithic ceramics by carbon fibres improves the tribological behaviour of ceramic materials. The lamellar graphite of carbon fibres can act as a natural third body, leading to low friction. The tribological behaviour of carbon-fibre (M40)-reinforced SiC matrix composites under different experimental conditions (velocity, load and temperature) is discussed in this paper. C-SiC composites are tested in sliding contact using a disc-on-disc tribometer. The results show that the behaviour of the contact is highly dependent on friction conditions. Friction transitions can occur during tests. The purpose of this paper is to identify the mechanisms which lead to these transitions. The main hypothesis concerns the mechanical and thermal fatigue phenomena. Under restrictive experimental conditions the C-SiC composites can be considered as self-lubricating materials. Self-lubricating conditions are experimentally given by a curve according to test temperature and pv parameter.