Wear Behavior of Ni-Based Composite Coatings with Dual Nano-SiC: Graphite Powder Mix

Abstract

This work explores the surface protection against wear provided by electroplated metal matrix composite coatings containing hard and lubricant particles. The second phase mix was selected to provide wear resistance by hardening the material and decreasing the friction coefficient. In this study, the capacity of providing wear protection by nano-SiC and self-lubrication by submicron graphite was addressed. Nickel-based composites with a dual powder mix of SiC 60 nm and graphite 400 nm, combined on a 10:10 g L−1 ratio, were produced by electrocodeposition. In addition, to better understand their synergy, mono-composites with SiC 60 nm or Graphite 400 nm with a powder load of 10 g L−1 were also produced. Pure nickel was also electrodeposited under the same conditions as a benchmark. Electron backscatter diffraction (EBSD) maps and chemical composition analysis were used to correlate the results from microhardness, wear resistance, and friction to the microstructure and particle incorporation rate. The wear rate tested by pin-on-disc decreased when the codeposition fraction and microhardness increased. Three main factors were determined to contribute to the coating hardness: Intrinsic hardness of the particle type, strengthening by grain refinement, and dispersion strengthening. The composites containing SiC provided the best wear protection due to the highest microhardness and grain refinement.