Detailed explanation of galvanizing steps

Step 1: Surface Cleaning

The first step in galvanizing is to clean the surface to be plated, removing dust, oil, and rust so that the surface can be effectively plated with zinc. For cleaning, alkaline cleaners are the best cleaners that will not degrade the surface. However, it is possible to acid-wash before using alkaline cleaners.

Before micro-cleaning with alkaline cleaners, a water bath at 100 to 180 degrees Celsius can help remove dirt. After cleaning with alkaline cleaners, immediately rinse the area with distilled water to avoid damaging the main surface of the material, which alkaline solutions can do. If the surface is not cleaned correctly, it may cause the zinc coating to flake or become damaged.

Step 2: Acid Washing

There may be many oxides on the surface, including rust that has already formed. Therefore, it is crucial to use an acid solution to remove these oxides and scale before galvanizing. The two most typical solutions used in the process are sulfuric acid and hydrochloric acid. The product is immersed in this acid solution. The immersion time, temperature, and acid concentration depend on the type of metal and the thickness of the scale.

After the parts are dipped into the acid solution for pickling, they are immediately rinsed with distilled water to avoid violent reactions and degradation of the surface.

Step 3: Preparation of the plating solution

The next step is to prepare the electrolyte for the electroplating process, also known as the plating bath. The plating solution is an ionic zinc solution that helps to simplify the electroplating process. It can be either acidic zinc or alkaline zinc.

1.Acidic zinc

High efficiency, fast deposition rate, excellent coverage, but poor deep plating ability and weak thickness distribution.

2.Alkaline zinc

Excellent thickness distribution, excellent throwing power, but low plating efficiency and low electrodeposition rate.

Step 4: Electrolysis setup and introduction of current

After selecting the electrolyte according to the product requirements and specifications, the actual deposition process starts with the introduction of current (DC). Zinc acts as an anode and couples to the negative terminal (cathode) of the substrate. When the current flows through the electrolyte, the zinc ions connect to the cathode (substrate), forming a thin zinc barrier layer on the surface.

In addition, there are two methods of electrolysis: rack plating and barrel plating.

1.Rack

Immerse the substrate in the electrolyte while fixed on the rack, suitable for large parts

2.Barrel

Place the substrate in the barrel and rotate it to obtain a uniform coating.

Step 5: Post-treatment

In order to eliminate any potential contaminants on the surface, the parts must be washed several times with distilled water after electroplating. After the plated products are washed, they must be dried before being sent to the warehouse. If necessary, passivators and sealants can also be used according to the standards required for surface treatment.