Effect of Fluorinated Graphite (FG) Addition on Friction Performance of FG-Ni/WC/CeO2 Cladding Layers over a Wide Temperature Range

This study fabricated fluorinated graphite (FG)-reinforced Ni/WC/CeO₂ cladding layers on 45 steel substrates using vacuum cladding technology. Their microstructure, phase composition, mechanical properties, and tribological behavior over a wide temperature range (25-800 °C) were systematically characterized. The results demonstrate that FG addition promotes the formation of a self-lubricating CeF₃ phase. The optimal CeF₃ phase formation efficiency occurred at a 1.5 wt% FG content (NWF15). The NWF15 cladding layer exhibited the smallest average grain size (15.88 nm) and the lowest porosity (0.1410%) among all samples. Mechanical testing revealed that this cladding layer possessed the highest microhardness (1062.7 ± 21.9 HV_0.2). Its H/E and H³/E² ratios, indicative of resistance to elastic strain and plastic deformation, reached 0.0489 and 0.0291, respectively. Tribological tests revealed pronounced temperature-dependent wear behavior: abrasive wear was predominant at 25 °C; adhesive wear dominated from 200 to 600 °C; and oxidative wear became the primary mechanism at 800 °C. Throughout this temperature range, the CeF₃ phase effectively reduced wear damage by suppressing groove propagation and providing effective lubrication, particularly under high-temperature conditions.