The Next Generation of Zinc Flake Coating Systems: PFAS-Free Technologies
The proposal to ban Per- and Polyfluoroalkyl substances (PFAS) is currently on everyone’s radar. New products will help fastener makers.
In the world of zinc flake coating systems, it’s all about combination. In general, zinc flake coating systems consist of two different layers that work together to ensure steel components are reliably protected against corrosion and have other functional properties such as resistance to chemicals and ease of assembly for threaded fasteners. With respect to terminology, the two individual coating layers which comprise the zinc flake system are referred to as a basecoat and a topcoat.
The basecoat and topcoat layers fulfill different functions within the coating system. The basecoat, which is applied directly to the surface of cleaned or pretreated parts, provides corrosion protection and significantly extends the life of the steel component. The basecoat layer is composed primarily of zinc in a matrix of thin “flakes” which are oriented on top of one another and aligned parallel to the surface of the component. When in contact with steel, zinc preferentially corrodes and sacrifices itself in favor of the steel. This property is commonly referred to as sacrificial corrosion protection. In addition to sacrificial corrosion protection, the basecoat will also protect the steel from corrosion even if the surface has been damaged, for example, by impact or from a scratch. This property is referred to as cathodic corrosion protection.