Influence of pulse frequency on physical and mechanical properties of Ni-GO composite coating

Coating serves as an effective and reliable barrier that protects surfaces against wear and less friction. Among the various deposition techniques, the pulse electrodeposition method has gained significant attention owing to its capability to generate tailored fine-grained, dense and uniform coatings. The properties of these coatings are highly influenced by several process parameters. This work explored the influence of pulse frequency on the physical and mechanical properties of fabricated nickel-graphene oxide (Ni-GO) composite coatings. The coatings were deposited on carbon steel with GO platelets concentration of 0.05 g/L through a 45-minute deposition at a temperature of 45 °C by pulse electrodeposition method. The pulse current frequency was varied from 200 Hz to 500 Hz. Surface morphology, surface roughness, coating thickness, microhardness, and phase structures were examined using Scanning Electron Microscope, Alicona InfiniteFocus, Micro-Vickers Hardness Testing Machine, and X-ray Diffractometer respectively. The highest coating hardness of 245.4 HV was obtained at the highest pulse frequency of 500 Hz. Surface roughness was drastically reduced to 0.3 µm as the pulse frequency increased to 500 Hz. The thickness of coatings increased with increasing pulse frequency, from 17.2 µm to 27.1 µm before decreasing to the lowest thickness of 14.0 µm at 500 Hz. The XRD spectrum revealed that increasing pulse frequency resulted in the formation of a refined granular coating structure exhibiting a prominent orientation along the Ni (220) crystal plane. In conclusion, the physical and mechanical characterisations of the coatings are notably associated with pulse current frequencies used in deposition process.