Dry sliding wear behaviour of metal toughened nanoceramics: A case study of aluminium-alumina nanocermets

Abstract

Sliding wear experiments were performed on the set of six Al–Al2O3 nanocermets, which were optimally designed with a tuned volumetric concentration of 20% Al and 80% Al2O3 to achieve a tailored cocooning of Al2O3 particles with thin Al film in the cermet structure. A combination of cryo-milling and room temperature-ball milling was carried out to prepare Al0.2-(Al2O3)0.8 powder mixtures and the nanocermets were prepared by spark plasma sintering (SPS). Pure Al, Al2O3 and nanocermet samples were subjected to a dry sliding wear test against a steel counter-body with the contact diameter of 1 mm to estimate their relative wear behaviour. The results suggest that the wear behaviour of nanocermets is comprised of both abrasive and adhesive losses. An increase in the milling duration of powder mixtures improved the wear resistance of the sintered nanocermets. Abrasion, adhesion, fracture, delamination and ploughing were found to be the major material removal mechanisms from the wear tracks. SEM was utilized to understand the morphological features of the wear tracks and wear debris, while XRD was used for the phase evaluation of the samples. HRTEM was used to observe the distribution of phases in the sintered nanocermet structure.