Studies on enhancement of surface mechanical properties of electrodeposited Ni-Co alloy coatings due to saccharin additive

NiCo alloy coatings were galvanostatically electrodeposited at room temperature from sulfate bath using saccharin (0 to 12 gL(-1)) as an additive agent. These alloy coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), contact angle, microhardness, Electrochemical impedance spectroscopy (EIS), salt immersion test and tribology techniques. The XRD study confirmed the formation of Ni-Co alloy with a face centered cubic (FCC) structure. Depending on saccharin addition, the Co content varied from 27 to 7 at.% The microhardness and corrosion resistance showed enhancement due to saccharin addition. Ni-Co alloy with a 12 at% Co content obtained from 10 g L-1 saccharin addition showed reduced grain size (12 nm) and hydrophobic surface (113 degrees) with the highest corrosion and wear resistant values as compared to others. Such coating on medium carbon steel fasteners showed significant enhancement in corrosion protection during salt immersion test. (C) 2014 Elsevier B.V. All rights reserved.