What materials should be used for corrosion protection when the slurry contains Cl ions?
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Dear teachers, hello. The slurry contains more than 300 mg/l of Cl ions, its pH level is between 3 and 4, and the temperature is around 30°C. What material would be suitable for anti-corrosion purposes in this case? If carbon steel lining is used for corrosion protection, what corrosion-resistant material should be used? If stainless steel is to be used, what grade of stainless steel material should be chosen? Among engineering plastics, which one is resistant to both acids (pH value of 3–4) and Cl ions (300 mg/l)? Please share your valuable opinions and experiences; thank you! ! !
For liquids that are acidic and contain chloride ions, there are several options: 1. Carbon steel lined with glass lining, suitable for equipment with stirring at temperatures above 100 degrees. 2. Spray or roll-coat fluoroplastic on carbon steel. 3. Under low-temperature and normal-pressure conditions, PPR or PPH engineering plastics can be used. The use of ordinary stainless steel is not recommended, as the commonly used 18-8 austenitic stainless steel cannot resist chloride corrosion.
Stainless steel 316L that has been used before is definitely fine, but it might be expensive. Carbon steel with enamel, rubber lining, or PTFE are all options; cost is the main factor to consider. FRP, PPH, and PE are all acceptable.
What kind of rubber to use? There is also a mixer inside the equipment for mixing, so wear resistance must be taken into account as well.
PPH is enough! For corrosion protection, epoxy resin or glass fiber can both be used!
Under acidic conditions, in systems containing chloride ions, 316L is not corrosion-resistant; chloride ions can destroy the crystal lattice of stainless steel, leading to intergranular corrosion. This phenomenon does not occur unless in high-concentration inert solvents that prevent the ionization of chloride ions – water-based systems are not suitable for this purpose!
At normal temperatures, a carbon steel lining with PE is sufficient – it’s cost-effective and durable
The recommended process is vacuum molding using a laminate of high-strength fabric and carbon fiber along with vinyl resin; this approach has shown good results in applications such as the stirrers for polysilicon hydrolysis tanks. If you are interested, you may come by.
Below 60 degrees, there is no problem with these chloride ions; the key is to maintain stable temperatures and chloride levels, avoiding large fluctuations.