Characteristics and Development of Electroless Nickel Plating
Introduction
Electroless nickel plating, also called as chemical or autocatalytic nickel plating, is one of the most widely used metal plating processes. It provides a uniform, corrosion-resistant coating to many surfaces from aluminum to zinc die castings and from low alloys steel to stainless steel. The process has been greatly improved since first patented in 1949. In the following sections, the characteristics, the development and an overview of electroless nickel plating will be presented.
The Characteristics of Electroless Nickel Plating
Electroless nickel plating has several distinct and desirable characteristics that are not present in other types of metal plating. First, it produces a uniform coating without needing power. This is because the deposition reactions occur as a result of a chemical reaction instead of an electrical current. Thus, holes, recesses and other irregular surfaces can all be plated evenly.
Second, due to the absence of electrical current, electroless nickel plating also does not produce hydrogen gas, which can be problematic and dangerous when plating other metals. Also, since the deposits produced through chemical reactions are much more steady and consistent, the process produces uniform particle size and plating deposits.
Third and lastly, the deposits are corrosion- and heat resistant. The nickel deposits can be further strengthened by post-treatments, such as heat treatment and chemical passivation. Together, they give the electroless nickel coating superior corrosion, temperature and wear resistance.
The Development of Electroless Nickel Plating
The history of electroless nickel plating can be traced back to 1949 when the process was first patented. Since then, the process has gone through many iterations and improvements. One of the earliest improvements was the conversion of the process from a simple chemical reaction to an autocatalytic process, which allowed for greater control of the deposition rate.
Later, the industry started to add hardeners, such as phosphorus, to the plating solutions for the extra material strength and better wear-resistance of the coating. This allowed for the use of electroless nickel plating in applications, such as industrial equipment, medical devices, and aerospace components where higher levels of wear and corrosion resistance were needed.
Moreover, the deposition rate of electroless nickel plating can be greatly accelerated by the use of a variety of additives, such as catalysts, buffer solutions, chelating agents and reducing agents. This allowed for faster processing times and further improvements in the uniformity of the deposits.
In the last few decades, there have also been improvements in post-treating processes, such as heat treatments and chemical passivations that are used on the electroless nickel deposits to further improve their properties. In combination with other plating processes, these treatments provide a durable, wear and corrosion-resistant coating with enhanced chemical and physical properties.
Conclusion
In conclusion, electroless nickel plating is an advanced metal plating process that provides uniform deposits with excellent corrosion and wear resistance. Its unique chemical and autocatalytic deposition process provide a uniform coating that can be accelerated by the use of additives. Moreover, post-treatments, such as heat treatments and chemical passivation, can further improve the properties of the deposited coating. By understanding the characteristics and development of electroless nickel plating, it can be used for a wide variety of industrial applications.
