What is corrosion and how does it affect your metal fencing? Do you know the answer to that question? Most likely you do, but just for the sake of those who might not have the answer, this is the topic we’ll discuss today.
So let’s start with building the foundation of our knowledge baggage and look into the definition of corrosion.
Corrosion is the gradual destruction of materials by chemical and/or electrochemical reaction with their environment. Therefore metal corrosion is the destruction of the metal by the chemical and/or electrochemical reaction with the environment it is in. And we all know that Melbourne’s winter can be quite harsh to its metal fencing. Rain, sometimes even hale, thank God that no snow, and then of course going to another extreme weather like very hot, hot summers. But as we are talking about corrosion, then the winter is the main season that is worrisome for us and metal fencing of course.
We know that using too many words that are very specific and don’t mean much for a person who hasn’t been interested in chemistry, and as soon as we bring in words like “electrochemical”, “sulfide”, or maybe even “oxide” your eyes and mind just drifts away as you’re probably thinking that hey, I just wanted to read a little bit about metal fencing and suddenly I am back in the chemistry class.
But we promise to explain it as gently as possible! So let’s start. Corrosion is an electrochemical reaction, like rusting – the formation of iron oxides. Just a fresh reminder that an oxide is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. This is where we stop getting too specific. Told you that it’s not going to be too complicated. But just too make sure that you won’t take corrosion same us rusting, we will remind (we already spoke about it in one of our previous blog posts) that rusting is a chemical process common with the metals containing iron. Simply put the corrosion process taking place when there is iron, is known as rusting.
Cool, now we know what corrosion is, so we can move on to see what types of corrosion there are when it comes to metal fencing. But just a second, not yet. Before we’ll mention few more things.
First is that all metals can corrode. And relying on the definition above that rusting is a corrosion process taking place where there is iron, then of course pure iron will corrode much quicker than let’s say stainless steel where iron is combined with other alloys, hence the more frequent usage of that material in construction.
And secondly there are group of metals that are called Noble metals. They are metals that are resistant to corrosion and oxidation in moist air. For example copper, mercury, silver, platinum and gold. But since they are not a metal fencing material as unlikely anyone in Melbourne will want to build a golden gate, we’ll move on.
1. General attack corrosion, and sometimes described also as a “uniform corrosion”, means that it uniformly proceeds over an exposed surface without appreciable localisation. Protective coatings like cathodic protection (CP) are effective in controlling uniform corrosion.
2. Localized corrosion. This is when corrosion attacks only part of the metal surface. Types of localized corrosion include pitting, crevice, and filiform corrosion.
- Pitting – small holes in the surface of metal as a result of corrosion.
- Crevice – occurs in stagnant locations like under gaskets.
- Filiform – occurs in surfaces where water can get under the coating. For example paint coatings.
3. Galvanic corrosion. This is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte, for example salt water. Many salts, such as sodium chloride, behave as electrolytes when dissolved in water as pure water will not behave as an electrolyte by itself.
4. Environmental cracking corrosion, meaning that when environmental conditions are stressful enough, some metal can begin to crack.
Effective corrosion prevention starts with the design stage with a proper understanding of the environmental conditions and metal properties. But this is the topic for another time. Meanwhile we hope that now you know a bit more about corrosion and its different types.
But if you have any question regarding metal fencing, and want to make sure that your new metal fence will be protected against corrosion, don’t hesitate and contact us today! Call on (03) 9753 4566, write an email on email@example.com, or just get a FREE online quote.