Corrosion Resistant Coatings
Experiencing corrosion? But don’t know how it’s forming? Or how to prevent it?
The answer may be beyond your parent metal.
Yet, corrosion protection will vary among industrial coatings. Each can have unique strengths. Ready to find the best?
First, we see "corrosion" and "chemical corrosion" the same. When a surface is attacked, it is a chemical (or electrochemical) reaction occurring between the surface and the environment. And the effects on surface properties or performance are negative.
Here are some common corrosion manifestations:
Fretting-- visible through pits, grooves, or debris relating to oxidation occurring at the asperities or "peaks" of contact surfaces. An example is vibration, which is the result of load in the presence of repeated relative motion.
Galvanic-- seen by pits, holes, or local oxidation products, the result of dissimilar metal. Here, one metal corrodes faster than it would alone, while the second corrodes slower than it would alone. Often, this is confused with coupled metals exhibiting increased decay based on differences in their electromotive force potentials.
Uniform-- manifested by equal measurable material loss over a larger surface area, which continues until failure. There is often predictability there. And performance is assured, though will diminish over time.Pitting-- is a localized form. Often difficult to detect, this type is considered more dangerous to design against. Pitting is initiated by local chemical or mechanical damage of protective oxide films or non metallic inclusions, theoretically forming a “battery” between an abnormal anode or cathode site.
Other forms of corrosion, including ‘Intergranular’, ‘Exfoliation’, ‘Stress’, and ‘Hydrogen Embrittlement’, can also result in localized cracking, severe loss in ductility, and increased residual tensile stresses.
So, how do we choose industrial corrosion resistant coatings?
What is the temperature of service? Can you define the corrosive strength or time of exposure? What about the corrosive medium. Is it a liquid? A vapor? Both? Under pressure? Indoor? Outdoors?
Your best coating choice must be environmentally compatible.
Is your coating inert (non reactive) to the environment? Consider surface porosity. Also known as pin holes or holidays, those microscopic voids allow penetration of corrosives, down to the base metal. Resistance to permeation matters.
Are there moving, mechanical parts? Don't ignore your parent metal (substrate). Take away its ability to form corrosive products and you can extend coating life, dramatically. So important under dynamic load, when coating thickness is restricted.
You've established environmental and parent metal compatibility. Don't stop there. To be sure there are no quality issues after applying the coating, consider the simple "wet sponge" or "high pot" (potential) test.
Highly effective with thermoset or thermoplastics, ceramics, or other non-conductive coatings, the test will reveal quickly, destructively, bare metal (coating void) by an electrical arc discharge.
Want some ideas for corrosion resistant coatings? Take a look at the following articles. Learn more about Chemours Teflon, PFA, FEP, ETFE (TEFZEL), ECTFE (HALAR by Solvay), PVDF (KYNAR), PEEK, and other products. Be sure not to overlook advancements in Anodizing, Vapor Deposition, Plating or Thermal Spray.
Need to make a better product? Or simply, make your product faster, more reliably, with less scrap? We share your goal for corrosion protection!
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