Ni-P coatings electroplating - A review, Part I: Pure Ni-P alloy

TL;DR

This review paper comprehensively surveys the electrodeposition of Ni-P alloy coatings, discussing their properties, microstructure, process variables, and advanced fabrication techniques like pulse plating and graded structures.

Contribution

It provides an extensive overview of Ni-P electroplating research, highlighting mechanisms, properties, and innovative fabrication methods not thoroughly covered before.

Findings

Ni-P coatings offer excellent corrosion and wear resistance.

Pulse plating and graded structures enhance coating properties.

Thermal treatment can increase hardness beyond traditional coatings.

Abstract

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.