Synthesis, characterization and applications of electroless Ni-B coatings-A review

Abstract

Electroless nickel coating process has experienced remarkable modifications since its invention by Branner and Riddell in 1946. This process has proven to be very useful for applying uniform, hard, wear resistant coatings on many kinds of substrates including metals, alloys and even non-metallic materials such as plastics. Ni-B coatings have high hardness (higher than tool steels) and high wear resistance (better than hard chromium coatings) but inferior corrosion resistant properties (Ni-P coatings).The successful development of Ni-P composite coatings through electroless coating process and attractive properties of Ni-B coatings have remarkably motivated the research community to develop cost effective and high performance Ni-B coatings to fulfill the challenging requirements of chemical, oil, automobile, petrochemical, electronic, aerospace and textile industries. Since reasonable advancements have been made in the field of electroless Ni-B coatings, it warrants, reviewing their development, physicochemical properties, and deposition mechanism to have deep insight of the earlier work and to design new processing techniques to cope up their existed limitations. In this article, a comprehensive review on electroless Ni-B coatings has been under taken with an emphasize on the coating bath compositions (nickel source, reducing agent, complexing agent, bath stabilizers etc),characterization techniques (structural, chemical and mechanical), factors affecting deposit properties and post coating treatments (heat treatment etc). Finally, some examples of the industrial applications of Ni-B coatings have also been discussed to have an idea about the diversity of their utility. 2016 The Authors.