Have you ever heard about
the galvanic series and wondered what it is or how it affects you? Luke Stone,
Technical Service Engineer at Cortec® Corporation, recently shared valuable
insights on that topic.
What Is the Galvanic
Series? Luke pointed to the hierarchy of metals as the main culprit for
galvanic corrosion. Different types of metals are considered more or less noble
and are arranged accordingly in the galvanic series. Platinum and gold are at
the top (more noble, less reactive) while aluminum and zinc (less noble, more
reactive) are near the bottom. Yellow metals are somewhere in the middle, with
iron and steel less noble than bronze and copper but more noble than aluminum
and zinc.
Why
Does Galvanic Corrosion Occur?
When different types of
metal that are far apart on the galvanic series come in contact with each
other, the corrosion potential of the more noble metal will be shifted to the
less noble metal. Luke explained that, in such cases, “things like copper are
going to preferentially cause things like steel to corrode. Things like steel
are going to preferentially cause things like aluminum to corrode….” He noted
that metal contact points, such as fasteners with different metals, are a good
“canary in the coal mine” to identify galvanic corrosion concerns.
How
to Avoid Galvanic Corrosion Surprises
Galvanic corrosion can take
people by surprise when they are only protecting one type of metal (e.g.,
steel) in a multi-metal system. While they may have thought that the brass or
aluminum in the system did not need corrosion protection due to higher
corrosion resistance, Luke explained that this can do a “severe disservice” by
pushing corrosion attack down the line to the less noble metal. Instead, the
key to preventing galvanic corrosion (when it is not possible to electrically
isolate dissimilar metals) is to choose a corrosion-preventative
product—whether paint, VpCI® packaging, or a liquid rust preventative—that
protects all types of metals in the system.
The comments above barely
scratch the surface of galvanic corrosion, but they offer a major step forward
in preventing it. If you have more questions, don’t hesitate to contact our
team at https://www.cortecvci.com/contact-us/ today to get started in your
fight against galvanic corrosion!
