Effect of Boriding on the Tribological Behavior of Monel 400 Alloy

The Monel 400 alloy, composed primarily of nickel and copper, offers excellent corrosion resistance but exhibits relatively low wear resistance, limiting its durability in demanding applications such as maritime industries, pumps, and valves. To address this, boriding thermochemical treatment was applied to enhance the surface hardness and wear resistance of the alloy. The process used a boriding powder containing 90% B4C and 10% KBF4 at 900 °C for 4 hours, avoiding silicon activators to prevent the formation of less hard nickel silicides. The resulting boride layer, predominantly Ni2B, Ni3B, and Ni4B3, was characterized using X-ray diffraction (XRD) and evaluated for adhesion via Rockwell C indentation (VDI 3198 standard). Wear performance was assessed through pin-on-disk tests on treated and untreated samples, analyzing wear rates, removed volume, and surface roughness using profilometry, confocal microscopy, and SEM. The borided layer achieved a hardness of up to 1600 HV0,01, demonstrating significantly improved wear resistance while maintaining strong adhesion to the substrate. This study highlights the potential of boriding as an effective treatment to extend the service life of Monel 400 in abrasive environments.