The final boss: corrosion
Even on vacation, some things remind you of the antenna system at home. Like here in the picture the corrosion formation at a stainless steel railing. Wait a minute - stainless steel and corrosion? Shouldn't stainless steel be rust-free? Yes, it is, but it sometimes helps other metals rust even faster. What's actually happening here?
Each element's chemical properties are largely defined by its outer electron shell. There are elements that readily give up electrons (base metals), and others that readily accept electrons (noble metals). One speaks of the oxidation states of an element or also molecule. The interesting aspect about this is - if you combine two materials with very different oxidation potentials, you can measure an electrical voltage between the two materials (admittedly, this is a very simplified representation of the processes). This property is extremely important in chemistry and physics because it is the basis for electric accumulators and batteries.
Through many experiments, chemists (especially Volta and Pfaff) already in the 18th century found out which combinations of materials produce particularly strong opposites of these properties, i.e. which combinations of substances produce the highest possible voltages. Hydrogen was taken as a reference, against which all elements had to have their potential measured. This resulted in the so-called electrochemical voltage series, i.e. a list of chemical elements with their voltage potentials to H (hydrogen). At one end there is fluorine with +2.89 volts, at the other end lithium with -3.04 volts. This exchange of electrons between two elements is called a "redox reaction", a combination of reduction (acceptance of electrons) and oxidation (release of electrons).
In practice, such redox reactions between two materials do not take place entirely by themselves; a medium such as water is usually still required. In the case of a rechargeable battery, this is referred to as an electrolyte. And that brings us to the rusting stainless steel railing. Here, the designers used a stainless steel tube as a railing, in itself - especially near the sea - a sensible decision. But then the safety inspection came and said that the railing must also be grounded. So they put a galvanized (base) steel clamp over the stainless steel pipe and connected it to the pipe next to it.
What happens now? The moist and salty sea air serves as an excellent electrolyte between the two electrodes made of different metals. A voltage potential is formed. The less noble metal (the zinc on the clamp) gives off electrons - it corrodes very strongly. The strong oxidation potential causes the oxygen in the air to combine with the zinc, and zinc oxide is formed. And zinc oxide (like many metal oxides) is brittle and unstable, it breaks down into small components when lightly stressed.
What could have been done better?
Either use clamps and screws made of the same material as the railing itself, i.e. stainless steel. But this is more expensive than galvanized steel goods. Alternatively, the metal parts could have been painted very heavily. Galvanizing is a good rust inhibitor in itself, but in an electrolytic compound to a precious metal, even that galvanizing won't resist. And salty sea air is a very good electrolyte, so it promotes this redox reaction.
The same thing happens with acid rain on our antennas. Sometimes even the slightly sulfurous exhaust air from the heating system in the neighboring chimney is enough. Together with the rainwater, an excellent electrolyte is formed at the antennas. If you now connect strongly different noble metals (different oxidation potentials) with each other, voltage potentials are formed, which can corrode almost any metal.
Therefore - always use similar metals for mast clamps and connecting elements. Either uniform stainless steel or otherwise exclusively well galvanized steels. If different metals have to be connected, always protect them well against the electrolyte, i.e. grease or paint them. And regularly check, inspect and replace. Then the antenna will last for several decades without corrosion.
And matching the topic of corrosion, we offer you these aluminum masts and tripods at a special price! So you can relax and leave your antennas outside and not worry, because these sliding masts and tripods are made of weather-resistant aluminum alloy, so they are rust-free. In addition, they are also very easy to transport and assemble!
The special offer is valid up to and including 19.03.2023.