The Role of Tribofilm Evolution on Tribological Behaviour of Ti3SiC2 Ceramic

The Ti3SiC2 compound is a thermodynamically stable nano-layered ternary carbide, that belongs to a family of over 50 ternary carbides and nitrides, so-called MAX phases. These phases are a new class of solids that possess a unique combination of properties: they are readily machinable, relatively soft for ceramics, but elastically stiff, and electrically and thermally conductive. However, only very few studies are dedicated to their tribological behavior. This paper presents some results on the tribological behavior of Ti3SiC2. During dry sliding on a Ti3SiC2 plane, a first regime of low friction and mild wear can be observed, with the build-up of a tribofilm on the counterface. Then, while in an apparently steady state, the tribological behavior suddenly turns to higher friction and severe wear of both counterfaces. Combining friction experiments and topographical observations of contacting surfaces during the first regime, we propose some explanations for such drastic transition in tribological behavior. While tribofilm thickness and roughness stabilize in the mild wear regime, the covering of the ball surface still increases. Thus, matter accumulation on the ball finally leads to seizure of the contact.