What is the corrosion resistance of ETFE anti-corrosion coating sprayed on the mixer

Source：www.dqig.cn Release date： 2025年12月29日

Information summary：ETFE anti-corrosion coating (commonly known as fluoroplastic coating) is the mainstream treatment solution for corrosion-resistant mixing equipment in industries such as chemical, metallurgical, and environmental protection. ETFE (ethylene tetrafluoroethylene copolymer) itself is a high-performance fluorine material, and the coating combines the corrosion resistance and inertness of fluorine mater

ETFE anti-corrosion coating (commonly known as fluoroplastic coating) is the mainstream treatment solution for corrosion-resistant mixing equipment in industries such as chemical, metallurgical, and environmental protection. ETFE (ethylene tetrafluoroethylene copolymer) itself is a high-performance fluorine material, and the coating combines the corrosion resistance and inertness of fluorine materials with the stability of the coating. It has excellent corrosion resistance and can be adapted to most highly corrosive media working conditions. The specific corrosion resistance, suitable media, and working conditions precautions are as follows:
1、 Core corrosion resistance: Broad spectrum corrosion resistance, resistant to strong corrosive media
The core advantage of ETFE anti-corrosion coating in terms of corrosion resistance lies in its strong chemical inertness, stable molecular structure, and resistance to reactions with acids, alkalis, salts, organic solvents, etc. The coating is dense and pore free (porosity ≤ 0.01%), which can isolate the medium from contact with the agitator substrate (carbon steel, stainless steel) and prevent corrosion from the root. The specific corrosion resistance performance can be divided into three types of core media:
Strong acid medium: It can withstand the vast majority of high-temperature strong acids without obvious corrosion and can withstand common strong acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, oxalic acid, etc. for a long time. It has a wide range of suitable concentrations and strong temperature adaptability. The core parameters are as follows:
Hydrochloric acid: at any concentration, with a tolerance temperature of ≤ 120 ℃, long-term immersion without pitting or peeling;
Sulfuric acid: concentration 0-98% (including fuming sulfuric acid), temperature tolerance ≤ 130 ℃, no corrosion, no swelling;
Nitric acid: concentration 0-68%, temperature tolerance ≤ 110 ℃, no oxidation reaction, good coating integrity maintained;
Hydrofluoric acid: concentration 0-50%, temperature tolerance ≤ 100 ℃, solves the pain point of conventional coatings that are not resistant to hydrofluoric acid, and is suitable for fluorine chemical and metallurgical stirring conditions.
2. Strong alkaline medium: Excellent resistance to strong alkalinity and high temperature strong alkaline immersion
The corrosion resistance of strong alkaline media far exceeds that of ordinary anti-corrosion coatings (such as epoxy resin, polyurethane), and can withstand strong alkalis such as sodium hydroxide, potassium hydroxide, calcium hydroxide, etc., suitable for harsh alkaline working conditions:
Sodium hydroxide: concentration 0-50%, temperature tolerance ≤ 120 ℃, long-term stirring and contact without bubbling or cracking;
Potassium hydroxide: concentration 0-40%, temperature tolerance ≤ 110 ℃, adhesion between coating and substrate does not weaken;
Weak alkali (ammonia water, sodium carbonate, etc.): any concentration, temperature tolerance ≤ 150 ℃, no corrosion reaction, suitable for environmentally friendly water treatment and fertilizer mixing conditions.
3. Salts and organic solvents: resistant to salt corrosion and solvents, suitable for complex mixed media
It can withstand the corrosion of strong oxidizing salts and heavy metal salts, as well as the immersion and erosion of the vast majority of organic solvents, and is suitable for multi medium mixing and stirring scenarios:
Salt medium: resistant to salt solutions such as sodium chloride, ferric chloride, copper sulfate, silver nitrate, etc. (at any concentration), with a temperature tolerance of ≤ 130 ℃, to prevent pitting corrosion and intergranular corrosion; Especially suitable for salt spray/salt solution mixing conditions such as seawater, brine, and electroplating wastewater, with no risk of corrosion;
Organic solvents: Resistant to common organic solvents such as methanol, ethanol, acetone, toluene, xylene, esters, and ethers, with a temperature tolerance of ≤ 120 ℃, and the coating does not swell, dissolve, or age; Not resistant to a few strong polar solvents (such as a mixture of fuming nitric acid and concentrated sulfuric acid), suitable for mixing conditions in chemical and pharmaceutical intermediates.
2、 Advanced corrosion resistance characteristics: balancing temperature resistance and erosion resistance, suitable for special working conditions of mixers
The agitator needs to withstand medium erosion, material friction, and temperature fluctuations during operation. The corrosion resistance of ETFE coating is not a single dimension, but presents a comprehensive corrosion resistance ability based on the working conditions. The key advanced characteristics are as follows:
1. Excellent temperature resistance, corrosion resistance does not deteriorate under high and low temperature conditions
The long-term use temperature range of the coating is -60 ℃~150 ℃, and it can withstand a high temperature of 180 ℃ in the short term. Under alternating high and low temperature conditions, the coating structure is stable and will not crack or peel off due to thermal expansion and contraction, maintaining consistent corrosion resistance; Solved the pain points of freezing and expansion of low-temperature media and accelerated corrosion of high-temperature media, and adapted to alternating cold and hot stirring conditions (such as reaction kettle stirring and refrigeration stirring equipment).
2. Anti erosion+wear-resistant, dual protection against corrosion and wear
When the mixer is running at high speed (speed ≤ 300r/min), the medium and solid particles will continuously wash the surface of the coating. The ETFE coating has a hardness of 3H (pencil hardness) and an adhesion of ≥ 5MPa (grid cut method), with both abrasion resistance and wear resistance:
Corrosion resistance: It can withstand the erosion of corrosive media with a flow rate of ≤ 5m/s, and has no coating damage after long-term use;
Wear resistance: When facing solid particles with a particle size of ≤ 5mm (such as mineral powder and chemical raw material particles), the coating wear amount is ≤ 0.001mm/1000h, and it still maintains compactness after wear, without affecting the corrosion resistance effect, and is suitable for solid-liquid mixing and stirring conditions.
3. Resistant to aging, oxidation, and long-term corrosion, with a long service life
ETFE coating has strong resistance to ultraviolet radiation and ozone aging, and is resistant to strong oxidizing media such as sodium hypochlorite and hydrogen peroxide. The coating has a long service life:
Static corrosion conditions (such as tank mixing): service life ≥ 8 years;
Dynamic stirring conditions (such as high-speed stirring in reaction vessels): service life ≥ 5 years;
Adverse working conditions (high temperature+strong corrosion+erosion): service life ≥ 3 years, far exceeding ordinary anti-corrosion coatings (epoxy resin service life of 1-2 years).
3、 Corrosion resistance limitations: Clearly identify unsuitable working conditions to avoid selection errors
Although ETFE coating has excellent corrosion resistance, there may be specific unsuitable working conditions that need to be avoided in advance to avoid coating failure:
1. High temperature and strong corrosion mixed medium: When the temperature tolerance exceeds 150 ℃ and accompanied by strong corrosion (such as concentrated nitric acid+concentrated sulfuric acid mixture above 180 ℃), the coating will soften and the corrosion resistance will decrease;
2. Strong reducing metal melting medium: Not resistant to strong reducing metals such as molten sodium and potassium, which can undergo chemical reactions and cause coating damage;
3. Strong scratching of sharp hard objects: The hardness of the coating is limited. If the mixed material contains sharp metal particles (particle size>10mm) and hard impurities, the coating is easily scratched under high-speed mixing, and the subsequent medium will corrode the substrate from the damaged area.
4、 Key guarantee for corrosion resistance of ETFE coating on mixer: construction process affects corrosion resistance effect
The corrosion resistance of coatings depends not only on the material itself, but also on the construction process that directly determines the density and adhesion of the coating. The core construction requirements must meet:
1. Substrate pretreatment: The surface of the mixer needs to be sandblasted for rust removal (Sa2.5 level), to remove oil stains and oxide scales. The roughness should be controlled at 50-80 μ m to improve the adhesion of the coating;
2. Coating thickness: The dry film thickness should be controlled at 200-300 μ m, with uniform thickness and no missed coating, to avoid uneven thickness and weak local corrosion resistance;
3. Curing process: High temperature curing (temperature 200-250 ℃, insulation for 2-3 hours) is adopted to ensure that the coating is dense and pore free, and to improve corrosion resistance and stability.

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