Preparation of pulse electrodeposited Ni-B/ZrC composite coatings and investigation of their mechanical properties and corrosion resistance

ZrC particles were embedded into Ni-B metal composite coatings by pulse electrodeposition in a Watt-type bath at 50 degrees C and 400 rpm with magnetic stirring. SEM, XPS, and AFM were used to characterize the appearance, chemical state, and surface roughness of the coating. The mechanical properties of deposits were measured by Vickers hardness and reciprocating friction, and scratches caused by linear reciprocating friction were analyzed with SEM and EDS in detail. In addition, the corrosion resistance was measured by the electrochemical impedance and polarization. The test results showed that the nanoparticles were uniformly dispersed across the substrate's surface, and the successful incorporation of nano-ZrC significantly changed the property of the nickel-boron alloy coating. When the ZrC concentration in the bath was 4 g/L, the coating exhibited the best mechanical properties and corrosion resistance, the Vickers microhardness of the Ni-B/ZrC metal composite coating increased from 523 HV (pure Ni-B) to 1073 HV, the friction coefficient decreased from 0.462 to 0.218 with a linear reciprocating sliding friction of 10 mm at a speed of 50 mm/min for 20 min under a load of 20 N. In 3.5 wt% NaCl solution at 25 degrees C and pH = 7, the impedance increased significantly, and corrosion potential became less negative (E = -0.316 V vs. SCE).