Metal Nobility

Understanding Electrolysis



Is it really Electrolysis?

We can measure it. We know it exists. We can see it's effects. We call it electrolysis. Yet, it has another name. Perhaps a more proper name; Galvanic Corrosion. Science has known about galvanic corrosion for years. Technically and properly, the term electrolysis is perhaps better used when describing a controlled electro-chemical process, such as in plating or manufacturing. The term galvanic corrosion is perhaps more accurately used when describing the destructive effects of metals when exposed to an electrolyte. Ocean water is a rather good electrolyte, and big boats are made from metal. It's not surprising that the US Navy knows a lot about galvanic corrosion.

The chart below shows that all metals are not created equally.



The Galvanic Series.


Active-Anodic Magnesium
These metals are most at risk- easiest to Zinc
corrode, least resistant for an electrolysis Aluminum
 attack.  Cadmium
  Cast Iron
ñ Nickel
ò Brass
  Stainless Steel
Noble-Cathodic Gold
Metals Least at risk of electrolysis. Graphite

*Note: this is the short list of metals common in automotive applications.


As you can see in the above chart most metals used in automotive cooling systems are not chosen for their corrosion resistance, or nobility. This only makes the task of keeping voltage out of the cooling system all that much more important.


It is important to note that aluminum is quite high on the above list, which explains why there are issues with aluminum durability when exposed to electrolysis  in a cooling system. It is also important to see that Magnesium ranks even higher on the list, which is why is makes a superior sacrificial anode in a cooling system. More technical information is available on the testing of magnesium as a automotive sacrificial anode here.


Magnesium anodes can be purchased here.


More Galvanic Series Data from Military Missile testing




Further In Depth Reading...

It's The Water | Too Much Information | Reserve Alkalinity | Step up to the Plate | Anode Data | Energy | Hungry Water