Zinc Plating Process – Rust is the worst enemy of almost all metals, and its corrosive effects can be disastrous. According to NASA, the cost of corrosion-related losses to the US industry is estimated to be at $276 billion per year, with a global amount nearing $1 trillion. Production and manufacturing, transportation, government, utilities, and infrastructure are most affected by corrosion.

Rust and its corrosive effects are the most severe hazard to metals in any sector. In every industry, corrosion can cause disruptions in production and manufacturing, transportation, utilities, and infrastructure, so what can you do to combat it? Zinc electroplating coats metals with a physical zinc layer that prevents rust from penetrating the metal beneath. The electroplating of Zinc, on the other hand, is a complicated process.

The zinc Plating process is a Bio-Friendly Alternative

The zinc plating process is a relatively new technology that did not acquire broad adoption until around 1980. Before then, cadmium was the metal of choice for electroplating in applications requiring the greatest corrosion resistance. On the other hand, cadmium is a highly toxic element that can cause cumulative poisoning over time.

While Zinc may not have the same anti-corrosion properties as cadmium, it is considered a more environmentally-friendly choice. As a result, cadmium plating is now generally limited to applications where the zinc plating process will not provide adequate corrosion protection or when additional degrees of protection are required. The use of cadmium in plating operations, on the other hand, must adhere to existing environmental requirements.

The steps in a typical zinc electroplating process are outlined below.

Cleaning the Substrate is the first step.

The first step is to clean the Substrate (the metal you want to plate); any pollution on the metal’s surface will prevent the zinc electroplating coating from adhering correctly to it. Typically, an alkaline detergent is used to clean the surface, with the metal soaking in an alkaline solution for 5–10 minutes. A temperature of 150 F is usually sufficient to remove the majority of the soil and debris. After the initial bath, the electro cleaner is used to finish the cleaning. Then, at the metal’s cathode or anode end, an electric charge is given, causing the solution to release oxygen or hydrogen, which cleans the substrate surface on a microscopic level.

Step 2: The Substrate Is Activated

To complete the Substrate’s preparation, it is submerged in various acid solutions to remove oxides and scales formed on the metal during manufacture, storage, and handling. Acids such as sulfuric acid or hydrochloric acid are frequently used in the activation process. The dipping duration, acid type, and temperature required for the zinc electroplating process are determined by the kind of metal and thickness of scale present.

Step 2:Preparation of the Plating Solution 

The zinc electroplating method necessitates the use of a specific electrolyte solution in which to submerge the Substrate. A zinc metal ionic solution and different chemicals are used in this plating bath to aid in the plating process. Acid Zinc baths are a fast and superior coating procedure. However, they have low throwing power and thickness distribution. On the other hand, Alkaline Zinc baths are less efficient and slower but generate superior thickness distribution and ductility.

Step 4: Electroplating using Zinc

Once the metal is ready for plating, it can be plated using one of two methods: rack plating or barrel plating. Rack plating is used for larger items and involves attaching them to metal racks that are then submerged in a tank containing the plating bath. Barrels plating is for smaller items, and instead of using a tank, the parts are placed in a barrel and turned to get a consistent finish. An electrical DC is delivered to a node in the bath for a predetermined amount of time, causing zinc ions to deposit on the cathode (the Substrate.) If the flow of electricity isn’t consistent, the zinc electroplating coating will be uneven.

Rinsing and drying are the final steps.

The zinc coating substrate must be washed with water and dried when the zinc electroplating is completed. If there is any remaining contamination, the surface may be cleaned many times to guarantee cleanliness. Passivates and sealers can be added after the rinsing if additional protection is necessary.

What is the Function of a Zinc Coating in Corrosion Prevention?

One of the most notable advantages of the zinc plating process is that it considerably improves the underlying Substrate’s corrosion resistance. But how does it happen? Zinc acts as a sacrificial layer in addition to producing a physical barrier. This means that the zinc coating, rather than the metal substrate it protects, will deteriorate.

Zinc also forms zinc oxide when it reacts with oxygen in the environment. After that, zinc oxide combines with water to make zinc hydroxide, which bonds with carbon dioxide to form zinc carbonate. To provide even more corrosion protection, the zinc carbonate clings to the Zinc on the coated metal.

Applications of Zinc Plating process

The zinc plating process offers a wide range of industrial applications. Zinc, for example, can be used to coat smaller metal parts like nuts, bolts, screws, and fasteners to protect them against corrosion. The majority of hardware parts are zinc-plated. In the automotive sector, a zinc plating process is commonly used to preserve brake pipes, brake callipers, and power steering components.

The zinc plating process is also utilised in manufacturing tanks, armoured personnel carriers, and other significant military equipment. The zinc plating process can also be used as a protective undercoat before painting, allowing for better paint adhesion.