Synthesis & Characterization of Graphene Enhanced Electroless Ni-P Composite Coatings

Abstract

Electroless Ni-P coating has attracted attention since few decades due to high hardness and corrosion resistance. However, applications that demand high wear and cracking resistance require coatings to exhibit toughness along with erosion and corrosion resistance. Extending applications of Ni-P coatings are impeded by cracking under Hertzian and scratching loads as well as erosion under high velocities. Graphene is known for high hardness and impermeability, so was selected as an additive for Ni-P coating matrix to produce Ni-P-graphene coatings having enhanced properties. Coatings were characterized by Hertzian-type indentation, scratch tests along with acoustic emission monitoring. The indents and scars were characterized by microscope to investigate toughening. Wear rates, toughening and damage mechanisms were identified and discussed in detail. Corrosion, erosion and erosion-corrosion properties of the developed coatings were also addressed. Graphene addition in Ni-P coating matrix is found to significantly improve its hardness, toughness, corrosion, erosion and erosion-corrosion attributes.