When selecting the material of the zinc pot, it is necessary to comprehensively consider corrosion resistance, high temperature resistance, mechanical strength, cost and production process requirements (such as continuous galvanizing or intermittent production).
Author: Marisa
When selecting the material of a zinc pot, it is necessary to comprehensively consider corrosion resistance, high temperature resistance, mechanical strength, cost, and production process requirements (such as continuous galvanizing or intermittent production). The following is an analysis of common materials and their applicability:
1. Mild Steel
Applicable scenarios:
Low-temperature zinc pot (such as hot-dip galvanizing temperature at 450~480℃).
Short-term use or small-batch production.
Advantages:
Low cost, easy processing, and can be repaired by welding.
Suitable for initial trial production or low-budget projects.
Disadvantages:
Fast corrosion rate: Zinc liquid reacts with iron to form a Fe-Zn alloy layer (zinc slag), causing the pot body to gradually become thinner, and the service life is usually only 3~6 months.
The zinc slag needs to be cleaned frequently, and the maintenance cost is high.
2. Heat-Resistant Steel
(1) Low-alloy heat-resistant steel (such as 16Mn, Q345R)
Short-term use (1~2 years), moderate cost, but still corrodes at high temperatures.
(2) High alloy steel (such as 316L stainless steel)
Applicable scenarios:
High temperature zinc liquid (480~550℃) or aluminum-zinc alloy (such as Galvalume).
Advantages:
Corrosion resistance is better than low carbon steel, and the service life can reach 1~3 years.
Disadvantages:
It will still react with zinc at high temperature and pitting will occur after long-term use.
High cost (3~5 times that of low carbon steel).
3. Cast Iron
Applicable scenarios:
Traditional intermittent hot-dip galvanizing (such as building parts, pipes).
Advantages:
It has better resistance to zinc liquid corrosion than low carbon steel, and the service life is about 1~2 years.
Large heat capacity and good temperature stability.
Disadvantages:
It is brittle and easy to crack (especially when the temperature changes suddenly).
It is heavy and difficult to replace.
4. Ceramic Linings
Types:
Silicon carbide (SiC): High temperature resistance (>1500℃), resistance to zinc liquid corrosion, lifespan of 5~10 years.
Silicon nitride (Si₃N₄): Higher strength, but extremely expensive.
Applicable scenarios:
Galvanizing lines with long-term continuous production (such as automotive panels, home appliance panels).
Advantages:
Almost no reaction with zinc liquid, rarely generates zinc slag.
High thermal efficiency (good thermal conductivity).
Disadvantages:
High brittleness, need to avoid mechanical shock.
High manufacturing cost (more than 10 times that of steel zinc pot).
5. Composite Materials
(1) Steel + ceramic lining
The outer layer provides strength for the steel structure, and the inner lining SiC or Al₂O₃ ceramic layer is anti-corrosion.
Lifespan 3~8 years, cost between steel and pure ceramic.
(2) Aluminized Steel
The surface aluminized layer can delay zinc corrosion, but it will still fail after long-term use.
Key factors for selection
Zinc temperature:
＜480℃: low carbon steel or heat-resistant steel.
480~550℃: high alloy steel or ceramic.
＞550℃: silicon carbide ceramic must be used.
Production mode:
Continuous production (such as plate galvanizing): ceramic or composite materials are preferred.
Intermittent production: heat-resistant steel or cast iron.
Zinc composition:
Containing aluminum-zinc alloy (such as 5% Al-Zn): aluminum corrosion-resistant materials (such as 316L stainless steel or SiC) are required.
Pure zinc liquid: lower cost materials can be selected.
Budget:
Short-term low cost: low carbon steel.
Long-term investment: ceramic or composite materials.
Maintenance and life extension suggestions
Regular slag removal: reduce the accumulation of Fe-Zn alloy layer.
Avoid temperature fluctuations: sudden changes in temperature will accelerate material fatigue.
Anti-corrosion coating: zinc corrosion-resistant coatings (such as borosilicate glass coatings) can be sprayed on the inner wall of the steel zinc pot.
If you need to further discuss the material selection for a specific process (such as galvanized aluminum-magnesium alloy), we can provide more details!