Effect of load on tribological behaviour of carbon-carbon composites

The effect of load on the tribological behaviour of three different two-dimensional carbon-carbon composites, including polyacrylonitrile (PAN) fibre-pitch matrix, PAN fibre-chemical vapour infiltrated (CVI) matrix, and pitch fibre-resin/CVI hybrid matrix composites has been compared. Results indicated that friction and wear rate variations with slide distance depended on load and the type of composite. The worn surface morphology was categorized into three types (I, II and III). The friction coefficient, wear rate and temperature all increased sharply when the transition from type I to type II occurred. When the powdery type II debris was compacted to form the lubricative type III debris, the friction coefficient and wear rate declined, although never approached their initial type I levels. For all composites, a higher load can accelerate the transition from type I to type II, but impedes the transition from type II to type III. Under 2.4 MPa, the type II morphology was never observed to transform into type III morphology in this study.