Electroless Nickel‐Based Coatings for Corrosion Protection Applications: Fid-Bau Portal

Electroless Nickel‐Based Coatings for Corrosion Protection Applications

Shashikala, A. R. / Sridhar, B. S. / Mishra, Sabin

With the increase in pollution, the corrosion effect on metal structures has increased, and there is a quest for long‐lasting coatings for corrosion protection applications. The barrier coatings must also provide abrasion, wear resistance, or improved mechanical, thermal, and electrical properties, along with corrosion protection if it has to be used for industrial and marine applications. Electrochemical coatings protect by blocking the corrosive particles and prevent electrochemical reactions of base metal with the corrosive environment. Electroless coating chemistry has gained a lot of focus on industrial applications and is dawning as a major metal finishing field. The electroless coating has unique physicochemical and mechanical properties compared to electroplating or chemical conversion coatings, which are used increasingly. Electroless plating does not require current, unlike electroplating, and the plating baths have higher throwing power. Electroless plating involves the self‐catalyzed redox reaction in which metal ions get reduced to metal with the help of reducing agents in the absence of an external current. Electroless deposition of thin metal films has recently attracted the attention of many scientists and technologists interested in surface coatings. This is mainly because of this film's considerable technical potential in the area of printed circuit boards (PCBs), magnetic tapes, etc. The most expensively used electroless coating is nickel‐based coatings which involve the plating of nickel alloy on the substrate in uncrystallized form using hypophosphite‐reducing agents. Electroless nickel coatings are used in automobile, food, oil, marine, electronic, and aerospace industries as a functional coating. They also possess excellent corrosion resistance. Hypophosphite plating baths provide uniform deposits, and phosphorus concentration can be controlled depending on the application field. Electroless nickel‐based alloy coatings are more prevalent on metals and insulators as they can be applied on intrinsic parts and provide excellent corrosion resistance. Many electroless nickel‐based alloy coatings like Ni–P, Ni–Cr–P, Ni–Cu–P, Ni–Co–P, Ni–W–P, and Ni–Zn–P are being used extensively for corrosion protection applications. This chapter provides a discussion on different electroless coatings for corrosion protection applications.