Electrodeposition and tribological properties of self-lubricating Ni–BaCr2O4 composite coatings

Abstract

In the present work, Ni–BaCr2O4 composite coatings were electrodeposited on superalloy Inconel 718 from a Watts type electrolyte containing BaCr2O4 particles, which were dispersed in suspension with the aid of a cationic surfactant cetyltrimethylammonium bromide (CTAB). BaCr2O4 particles were synthesized by solid state reaction method and had a size range of 0.8–2 μm. The content of BaCr2O4 incorporated into composite coatings depended mainly upon the BaCr2O4 powder concentration in bath, cathode current density and temperature condition in the electrolyte. Microstructure and microhardness of Ni–BaCr2O4 composite coatings were investigated with scanning electron microscope (SEM), X-ray diffractometer (XRD) and microhardness tester. The friction and wear properties of Ni–BaCr2O4 composite coatings containing various amounts of BaCr2O4 particles were studied with a ball-on-disk friction and wear tester in sliding against alumina ball. Ni–BaCr2O4 composite coatings exhibits a distinctly low friction coefficient and a small wear rate as contrasted with pure nickel coating and the substrate. The wear resistance of Ni–BaCr2O4 composite coating electrodeposited on superalloy Inconel 718 increases with increasing BaCr2O4 content. The wear mechanisms of Ni–BaCr2O4 composite coatings were proposed as contrasted with pure Ni coatings and the superalloy substrate at identical wear conditions.