The metals used for various industrial products are exposed to the action of the environment, so they can undergo physicochemical transformations that can degrade them, reduce their useful life and, in the worst case, destroy them. The springs are also susceptible to this damage, which is why they are required to have some type of coating that, depending on the application, protects them against corrosion, provides them with properties that they do not have, or fulfills a decorative function.
Coatings are usually applied to protect another metal from corrosion, using metals such as aluminum, zinc and cadmium, which are the most effective for protecting iron, and can also sometimes cover pores, scratches or edges.
On other occasions, to provide them with greater hardness and resistance to mechanical wear, a metal such as nickel, tin, copper, or a stainless steel alloy can be used to resist corrosion. In these cases it is important that the metal to be covered does not have pores or other defects.
The materials that will be used for the manufacture of springs are chosen based on the required mechanical characteristics, such as electrical conduction, operating temperature, work environment, type of force to resist, among others. Carbon steel is one of the most widely used metals for springs, and while it is very strong and reliable, it is prone to corrosion, so it is often electroplated zinc plated or a non-metallic finish such as oil is used. For their part, copper or bronze alloys are used for applications in which the spring requires conductivity, in addition to being effective in humid atmospheres.
Phosphate coatings use layers of iron, zinc and manganese to provide a coating that increases mechanical resistance and reduces friction when in contact with other mechanical parts, which is why they are frequently used in iron or steel springs for different industries. .
This coating consists of immersing the pieces to be treated in aqueous solutions of phosphated chemical compounds to produce a series of chemical reactions that transform the surface into a non-metallic layer of phosphates.
