Study on the structure and properties of trivalent Cr-ZrC composite coatings with ZrC content regulated by current density

In this study, Cr-ZrC composite coatings were fabricated for the first time via trivalent chromium (Cr(III)) electrodeposition, and the influence of current density on the microstructural evolution, microhardness, and tribological behaviors of the as-prepared coatings was systematically investigated. The results show that the composite coatings presented an amorphous matrix with uniformly dispersed ZrC particles, and an amorphous interface was observed between the Cr matrix and ZrC particles, which ensures robust interfacial bonding. The thickness of Cr-ZrC composite coatings and the content of ZrC particles both increase as current density rises. When the current density reached 20 A/dm 2 , the ZrC content attained a maximum of 15.55 vol% along with a coating thickness of 9.81 μm, and the coating prepared under this current density exhibited the highest microhardness of 1239.8 ± 20.7 HV, which was approximately 66.4 % higher than that of the pure Cr(III) coating (without ZrC incorporation). Tribological tests indicated that the Cr-ZrC composite coatings achieved optimal wear resistance at a current density of 16 A/dm 2 , with a friction coefficient of 0.43 and a wear rate of 9.75 × 10 −6  mm 3 ·N −1 ·m −1 under this condition. Collectively, these findings provide a critical theoretical and experimental basis for optimizing Cr-ZrC composite coatings and clarify the key regulatory mechanism of current density on their structure-property correlation.