Tribological characterization of magnesium matrix nanocomposites prepared by spark plasma sintering

This study investigated the effect of short SiC nanofiber content on the microstructure, microhardness, friction behavior, tribofilm stability, and wear mechanisms of magnesium composites prepared by spark plasma sintering.Unreinforced Mg (H1) was compared with Mg--3 wt.% SiC nf -1 wt.% GNP (H3) and Mg-6 wt.% SiC nf -1 wt.% GNP (H6) composites.Prior to tribological testing, a temporary graphite layer was mechanically applied to the polished surfaces.Reciprocating sliding tests against a 6 mm diameter ZrO2 ball were performed under normal loads of 3 and 5 N at a frequency of 1 Hz, a stroke length of 5 mm, and a total of 1000 complete cycles.The microstructure, wear-track morphology, and elemental distribution were examined by optical microscopy, SEM/EDS, and 3D profilometry.The composites exhibited a network-like distribution of reinforcing constituents, predominantly along the interfaces of Mg-rich regions.The highest microhardness, 65.6 ± 4.7 HV0.1, was measured for H3.At 3 N, H3 and H6 maintained a stable coefficient of friction of approximately 0.15-0.17throughout the entire test, whereas H1 exhibited an increase above 0.30 after approximately 450 s.At 5 N, failure of the low-friction regime occurred after approximately 270 s for H1, 680 s for H3, and 920 s for H6.The lowest wear rates were recorded for H6, reaching 4.9 × 10 -6 mm 3 N -1 m -1 at 3 N and 1.72 × 10 -4 mm 3 N -1 m -1 at 5 N.The improved tribological performance of the composites was associated with the mechanical support of a heterogeneous carbon-oxide tribofilm by the SiC nanofibers.H3 exhibited the most favorable friction behavior at 3 N, whereas H6 provided the highest load-bearing capacity and the lowest wear rate under both applied loads.