Magnesium and its alloys are undeniably popular metallic options in the world of manufacturing. Long heralded for its light weight and great electrical and mechanical properties, the metal is the third most used structural metal behind aluminum and iron. However, even with such great properties, it still runs the risk of corrosion as it is highly susceptible to things like salt water. Because of this, engineers have developed plating on magnesium to give it even more beneficial properties while simultaneously negating its weaknesses.
Plating, though a complex process, is a simple idea. It’s the act of coating something in a different material for a specific purpose. Back in the early days of plating, small sheets of silver were adhered to brass and then made into silverware. These goods looked rich but didn’t cost the middle class that bought them a fortune. For modern uses, it’s a way of strengthening the current properties of a material while adding new ones. Certain coatings, for instance, increase lubricity.
As technology has advanced, so, too, have plating methods. Including electroless nickel plating, wet painting, resin powder coating and chemical conversion coatings, there are many methods to achieve the functional, protective or decorative goals manufacturers have in mind. That being said, plating on magnesium follows a pretty specific order.
As with any project, it’s best to set up everything before starting. During this stage, the magnesium product is finalized with polishing, blasting or brushing. As the metal is well known to tarnish, it typically undergoes a final bit of polishing and buffing to preserve the shine. In addition, the space where this happens is filled with suction ducts and pipes to minimize and accumulation of dust, a potential fire hazard. Employees often where special clothing to deter dust accumulation on their bodies.
Next, the magnesium is cleaned using a solvent to remove any wax or oil build up along the exterior. Then it moves onto something called acid pickling. This removes all other contaminants, such as sand particles or other residues missed by the solvent. This step is extremely important as it guarantees the surface is as smooth as possible for a perfect plating.
Now that it is fully cleaned, the magnesium can be coated without any concern of corrosion from a small remainder of contamination. This process is actually broken into two phases. The first is known as conversion coating and involves the application of a coating that will improve the adhesion of the actual component that will make up the outer coat. This layer also acts as additional protection from corrosion.
The second phase is called organic coating. The material used for this varies widely depending on what magnesium alloy is being used. This is also the layer that adds the additional benefits that make the metal such a versatile addition to most industries.