  In the electroplating industry Ni-P coatings are extensively employed owing
to their excellent properties which enable substrate protection against
corrosion and wear. Depending on their composition and structure, as-plated
deposits demonstrate good mechanical, tribological and electrochemical
features, catalytic activity but also beneficial magnetic characteristics. With
subsequent thermal treatment hardness of Ni-P metal-metalloid system can
approach or be even higher than that of hard Cr coatings. The purpose of this
paper is to provide a general survey of the research work dealing with the
electrodeposition of Ni-P binary alloy coatings. Proposed phosphorus
incorporation mechanisms, Ni-P alloy microstructure before and after thermal
treatment, its mechanical, tribological, corrosion, catalytic and magnetic
properties are considered, so are the key process variables influencing
phosphorus content in the deposits and the roles of the main electrolytic bath
constituents. Findings on the merits of employing pulse plating and fabrication
of unconventional (layered and functionally graded) structures are succinctly
explored.
