The tribological behavior evolution of TiB2/Al composites from running-in stage to steady stage

The purpose of this study was to investigate the characteristics of a friction and wear transition from the running-in stage to the steady-state stage for an Al-based composite containing TiB2 particles and fabricated by a pressure infiltration technique. The dry sliding friction and wear behavior was investigated using a 3.98mm diameter AISI 52100 steel ball-on-disk geometry under applied loads of 1N and 3N. Microstructural characterization and element distribution were carried out using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). 3D surface topographies and roughness of the wear surfaces were measured using confocal laser scanning microscopy (CLSM). The results indicated that the formation of a transfer film and boric acid (H3BO3) was the main reason for the low friction coefficient of about 0.16 at a load of 1N. An increase of friction coefficient was caused by the abrasion of pulled-out TiB2 particles. In the running-in stage at an applied load of 3N, abrasive wear dominated and resulted in the formation of grooves and pulled-out TiB2 particles. In addition, at a steady-stage friction coefficient of 0.6, severe three-body abrasive wear and oxidative wear were the dominant wear mechanisms. An excellent correlation was found between friction coefficient and surface roughness, as measured by 3D topography.