Fretting wear behavior of in-situ (TiC+TiB) reinforced Ti-based composite by laser power bed fusion: Role of friction counterparts and operating frequency

Abstract

The CP-Ti alloy reinforced by whisker-shaped TiB and nearly granular TiC was in-situ fabricated through laser powder-bed fusion (LPBF) of Ti-B4C-C composite system. The influences of operating frequency and counterpart materials on fretting wear behavior of the LPBF-ed composite in 0.9 wt% NaCl solution were investigated. The results reveal that a relative density of nearly 99.1% and high-quality surface of the LPBF-ed composite are acquired as a result of the intense thermodynamics within molten pool induced by the carbon additive. For the ZrO2 counterpart, the average coefficient of friction (COF) of composite experienced an initially sharp reduction from 0.42 to 0.16 and a subsequently gradual decrease to 0.13 as successively increasing the operating frequency. The determined wear mechanism transferred from the severe abrasive wear with moderate adhesion wear to the predominated abrasive wear with a reduction of wear volume due to the formation of titanium oxide layer caused by the accumulation of increased wear debris. For GCr15 counterpart, the average COF nearly remained stable, but the wear volume exhibited a moderate increase and a subsequent reduction to 3.56 × 106 μm3, due to the partial or nearly complete covering of the accumulated wear debris on the worn surface.