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In the current study, electro-deposition of hybrid coatings consisting of Cr simultaneously reinforced with nano-scale 3 mol% yttria-stabilized zirconia (YSZ) along with hexagonal boron nitride (Cr-YSZ-BN), graphene (Cr-YSZ-Gr), and diamond (Cr-YSZ-D) was performed using an environmentally-benign trivalent Cr bath. Abrasive wear with ploughing for scratch test is recognized as the dominant wear mechanism in coatings; on increasing the scratch speed, gross spallation occurs in the BN reinforced coatings. While graphene and diamond were strongly adherent to the substrate with no signs of delamination. During fretting, oxidative and three-body abrasive wear in wedge formation mode with severe crack networking was observed in Cr-YSZ-BN. Micro-ploughing was active with intermittent cracking in Cr-YSZ-Gr coatings, indicating lower wear (via solid-lubrication by graphene). Diamond added coating, on the other hand, exhibits fewer cracks with ploughing. High hardness and elastic modulus with a maximum of ~26 GPa and 245 GPa, respectively, were obtained for Cr-YSZ-D coating with a minimum wear rate of ~3.5×10−11 m3/Nm (fretting) and 3.8×10−5 mm3/Nm (scratching). Further, rigid sp3 hybridization of carbon atoms in Cr-YSZ-D leads to the strong interlocking between Cr matrix and diamond, thereby lowering the wear damage of the coating system. The unique combination and uniform dispersion of YSZ and diamond particles displayed enhanced friction and wear resistance (k ~ 1.4×10−3), primarily due to the inherent high hardness of diamond and matrix strengthening by nano and micro-scale particles. Therefore, Cr-YSZ-D coating system emerges out as a highly robust coating capable of providing enhanced damage tolerance towards wear for various tribological applications. • Synergistic YSZ reinforcement with BN, graphene, and diamond in Cr-matrix. • Reduced crystallite size (~15 nm) and high dislocation density (~1011 cm-2) in reinforced coatings. • High compressive residual stresses (~720–1230 MPa) in hybrid coatings. • High fretting damage tolerance (wear rate of ~3.5 × 10–11 m3/Nm) in Cr-YSZ-D hybrid coating. • Low micro-scratch damage (wear rate of 3.8 × 10-5 mm3/Nm) in Cr-YSZ-D hybrid coating. [ABSTRACT FROM AUTHOR]

The objective of this article is to examine the influence of different weight percentages (wt%) of graphene nanoplatelets (GNPs) on the behavior of mechanical and abrasive wear. Furthermore, the influence of operating parameters, such as, different degrees of applied loads and abrading distance (5‐20 N and 100‐250 m, respectively) at a rotational speed of 200 rpm (1.047 m/s) against SiC paper of 400 grit size was studied. From the present study, it was possible to establish that performance of the glass fabric‐reinforced epoxy composite materials can be improved with incorporation of GNPs. Moreover, incorporation of a large amount (1 wt%) of GNPs was found to noticeably enhance the tribo‐performance, ILSS, and hardness of the composite materials. However, the tensile strength was noted to increase negligibly with incorporation of 1 wt% of GNPs as compared to 0.5 wt% of GNPs. To get an insight into the wear mechanisms, the abraded surface of the tribological samples was examined by scanning electronic microscopy and energy dispersive X‐ray. Their morphology was correlated with wear volume and specific wear rate data trends. Worn surface features analysis indicated that incorporation of GNPs mainly improved the fiber‐matrix interface, which resists easy pullout of fibers from matrix/fillers and enables higher wear resistance. [ABSTRACT FROM AUTHOR]