Sliding wear of MAX phase composites Ti3SiC2–TiC and Ti3AlC2–Ti2AlC at 400 °C and the influence of counterface material (steel, Al2O3, and Si3N4) on wear behaviour.

This study explores the feasibility of employing MAX phase composite as impregnated solid lubricants and/or as bulk material for advanced high temperature tribological applications. The development of microstructure of Ti-based MAX phase composites Ti 3 SiC 2 –TiC and Ti 3 AlC 2 –Ti 2 AlC fabricated by spark plasma sintering and their dry sliding tribological properties against bearing steel, Si 3 N 4 , and Al 2 O 3 counterfaces were investigated using a ball on disc tribometer at 400 °C. An orientation relationship between the Ti 3 SiC 2 matrix and TiC particle was established wherein Ti 3 SiC 2 /TiC interphase is a coherent boundary from which Ti 3 SiC 2 grows epitaxially from TiC. Against steel, the MAX phase composites – in stark contrast to Si 3 N 4 and Al 2 O 3 – exhibited a negative wear behaviour due to the excessive wear and subsequent sintering of the transferred Fe particles at the sliding interface. Intrinsic lubrication mechanisms involving tribo-oxidation, tribochemical reaction, and mechanochemical reaction played a vital role in the friction and wear properties. The friction and wear properties of the Ti 3 AlC 2 –Ti 2 AlC MAX phase composite was superior to the Ti 3 SiC 2 –TiC composite owing to better oxidation kinetics governing the oxide growth and their retention. Evidently, the wear of the MAX phase is expected to proceed upon extensive deformation incorporating a range of microscale micromechanisms. • Ti 3 SiC 2 /TiC interface is a coherent interface with low interfacial energy. • Tribo-oxidation enhances tribosintering • Oxidation kinetics plays a role in tribofilm spallation. • The role of counterface material was studied. • Wear of MAX phase proceeds by deformation. [ABSTRACT FROM AUTHOR]