Role of fluxing agents

The role of fluxing agents in hot dip galvanizing mainly includes the following aspects:

Author: Anna

The role of fluxing agents in hot dip galvanizing mainly includes the following aspects:

1. Cleaning the steel surface: fluxing agents can remove iron salts, oxides and other dirt from the steel surface, ensuring a clean steel surface and facilitating the subsequent galvanizing process.
2. Purification of liquid zinc: fluxing agents can purify the liquid phase zinc at the point where the steel piece is immersed in the zinc solution, so that the steel piece and the liquid zinc can be quickly infiltrated and reacted to form an iron-zinc alloy layer.
3. Air barrier: The fluxing agent deposits a salt film on the surface of the steel piece, isolating the surface of the steel piece from the air and preventing further oxidation.
4. Reduce surface tension: fluxing agent can reduce the tension on the steel surface when it is decomposed by heat, so that the zinc liquid can be better attached to the steel substrate and the alloying process can be carried out smoothly.
5. Improvement of wettability and adhesion: fluxing agent can improve the activity and wettability of the steel surface, so that the zinc liquid can be smoothly attached and reacted to form a high-quality alloy layer.

The main components of fluxing agents and their mechanism of action:

• Zinc chloride (ZnCl₂): easy to absorb moisture, heat decomposition can reduce the surface tension, and promote the reaction between the zinc liquid and the steel matrix2.
• Ammonium chloride (NH₄Cl): volatile, reacts when in contact with hot zinc liquids, helps to purify steel surfaces and prevents oxidation2.
• Mixture: A mixture of zinc chloride and ammonium chloride is usually used to bring out the advantages of both and to improve the effect of the plating aid2.

Methods and precautions for using fluxing agents:

• Dipping or spraying: dipping or spraying fluxing agent after pickling and descaling of plated parts to facilitate galvanization2.
• Control temperature and time: the dipping time should be as short as possible to reduce the solvent dissolution of iron parts and the production of iron salts, the drying temperature should be properly controlled to avoid solvent volatilization affecting the effect2.

Through the above measures, the fluxing agent plays an important role in the hot dip plating process to ensure the quality and corrosion resistance of the coating.