Abstract
Nickel electrodeposits are widely employed in industrial applications owing to their excellent resistance to corrosion, wear, and elevated temperatures.They serve in decorative coatings, functional coatings, and electroforming, with the final performance strongly influenced by deposition parameters.Among these, the electrolyte bath composition, typically based on chloride, sulfate, sulfamate, or Watts bath, plays a critical role.The incorporation of additives into these baths is critical for tailoring the properties of nickel coatings, as they modulate nucleation, growth and surface evolution during deposition.Additives are broadly categorized as brighteners, grain refiners, levelers, surfactants, and hardeners, each contributing distinct effects on microstructure, morphology, mechanical performance, and corrosion behavior.This review systematically examines the role of additives in nickel electrodeposition, emphasizing their mechanism of action, the resulting deposit characteristics, and their applications.Particular attention is given to saccharin, the most widely employed additive, which functions as both a grain refiner and brightener, and to surfactants such as sodium dodecyl sulfate (SDS) and polyvinyl pyrrolidone (PVP).Which significantly enhances corrosion resistance.The discussion also highlights critical considerations regarding sulfur-containing additives where excessive incorporation can compromise coating integrity.By integrating insights from recent literature, this review provides a comprehensive framework for understanding how additive selection and optimization enable the design of nickel coatings with tailored functional and aesthetic properties.