Teflon Corrosion Resistant Coatings
Teflon corrosion resistant coatings, including polytetrafluoroethylene (DuPont PTFE) can be an excellent means for corrosion protection.
For chemical resistance, consider too, DuPont FEP, PFA, ETFE, other manufacturers too, including the ECTFE fluoropolymer. Absorption rates are comparatively lower than almost all other thermoplastics. They absorb practically no common acids or bases at higher temperatures (300 degrees Fahrenheit for ECTFE or ETFE). And weight increases are generally less than 1% when exposed at elevated temperatures for long periods. Aqueous solutions are absorbed little. Moisture absorption is typically less than 0.01% at ambient temperature and pressure.
Gases and vapors, too, from Teflon corrosion resistant coatings show low permeation rates than for other thermoplastics. In general, permeation increases with temperature, pressure, and surface area contact, but decreases with increased thickness.
Coating selection should be determined by the chemical environment, the time of exposure, service temperature, and mechanics. For static applications involving no moving parts, higher build coatings are ideal. This is especially true with work pieces submerged in aqueous solutions or immersed in corrosive vapors, over longer periods.
For applications involving moving parts, you may be constrained to lower coating builds from Teflon corrosion resistant coatings. Sometimes temperature, alone, will govern coating selection. So be sure your service provider fully understands your environmental requirements, or the chemical resistance of his materials.