What is electroplating?
Electroplating is the process of depositing a metal onto another by hydrolysis, primarily to prevent metal corrosion or for ornamental purposes. An electric current reduces dissolved metal cations, resulting in a thin, coherent metal coating on the electrode. Electroplating is frequently used in the electrical oxidation of anions on a solid substrate, such as producing silver chloride on silver wire to make silver chloride electrodes.
Electroplating is mainly used to change the surface properties of an object (for example, corrosion resistance, lubricity, and abrasion resistance). Still, it can also be used to add thickness or create objects by electro shaping.
Plating on polymers and ceramics has several advantages. A layer of gold, silver, nickel, or copper on these brittle materials will make them stronger and more durable and increase their corrosion resistance. The electroplating technique can also add a metallic appearance to a ceramic or plastic product, making it more appealing to the eye.
Although Electroplating these fragile materials is possible, it is a more complex procedure than metal-on-metal coating. As a result, many issues can arise, lowering the quality of the end product. Flaking is one of the most common — and preventable — problems.
IN ELECTROPLATING, WHAT IS FLAKING?
When metal does not cling well enough to the surface of a ceramic or plastic substrate, flaking happens. The coating will lift, detach, and peel away from the surface, leaving bare patches. Flaking will not only leave the goods vulnerable, but it will also detract from their attractiveness.
WHAT CAUSES CERAMICS AND PLASTICS PLATING TO FLAKE?
Flaking can happen for a variety of causes, including:
Metal coatings do not cling as well to plastics and ceramics as they do to other metals due to insufficient surface preparation. To metalize the material, increase adhesion, and reduce the possibility of flaking, sufficient surface preparation is required. In addition, surface preparation will remove machine oils and other contaminants from the substrate and “activate” it. Because no two plastic or ceramic goods are identical, the preparation process will differ based on the material.
Electroless plating was not implemented: Electroless plating, which provides a metal coating without the use of electricity, is a step in the surface preparation process. For example, nickel or copper electroplated base coat might help the top layer stick and avoid flaking.
Contaminated plating bath: Failure to monitor the electrolyte solution during plating might accumulate various impurities. These foreign substances can impede the metal ions, preventing the coating from adhering properly. Many of these things may generally be removed by filtering the bath.
Excessively thick coating: Some metal finishing businesses believe that plastic and ceramic materials require a thicker coating to safeguard them due to their comparatively fragile composition. On the other hand, an overly thick covering might become brittle and eventually “flake off” the product. Each material type requires a different thickness, which an experienced plater can determine.
Poor adherence is a typical issue that can compromise an electroplated coating’s effectiveness and lifetime. Flaking is a common sign of poor adherence, which happens when the coating lifts, separates and peels away from the substrate’s surface. This leaves vast, naked or virtually bare areas that the covering can no longer adequately protect. In addition, flaked coating pieces are often brittle in nature and have long defined edges.
Flaking Identification Tests
Several tests may be used to detect flaking in plated parts. The bend test, for example, involves placing a sample in a vice and repeatedly bending it over a mandrel until the base metal fails. Any flaking or peeling will be seen if the part is examined under magnification. Another alternative is the heat-quench test, which involves baking the item in an oven and then chilling it in room-temperature water. A visual inspection of the cooled part will reveal flaking, blistering, or other adhesion difficulties.
Smart Microns has the metal finishing experience and skills to choose and apply the best coating process for preventing flaking and other typical adhesion issues.