Most people believe that the world they live in is a calm and comfortable place. In reality, it is more hostile than they can possibly imagine. Everything on Earth is locked in a constant battle for survival. The environment is so fragile that even the slightest shift in the balance could push life to extinction.
It is only when living things learned to adapt and evolve that the world became less hostile. Yet the fact remains that when the world can no longer support life as we know it, everything will perish and decompose. All that will be left is a barren wasteland with nothing more than dust and rocks.
The famous adage “from dust you came, and to dust you shall return,” is originally addressed to all living things. It pertains to the natural process of decomposition when a carbon-based material loses resistance against the effects of its environment. It turns out that this principle applies to inorganic materials as well. The only difference is that their decomposition takes a lot longer and is influenced by a greater variety of factors. This process is more commonly known as corrosion.
Corrosion of Metals
Corrosion takes place when a certain material is placed in an environment where it is chemically unstable. Metals are among the best examples of materials that undergo this process. Despite being tougher and more resilient than most other materials, they have their share of weakness. There are certain chemicals that they don’t react well to. If you’ve seen the film Batman vs. Superman, particularly the part where Batman was able to weaken Superman by exposing him to kryptonite, it works pretty much the same way.
Understanding corrosion is important because it affects the properties for which metals are used in a vast range of applications. By knowing which element in an alloy reacts to which substance, metallurgists can more easily determine the best way to adjust the alloy’s composition to form a more corrosion-resistant material.
Perhaps that most widely held catalyst for corrosion is oxygen because most metals react to it. This has been proven by Antoine Lavoisier, the French chemist who also authored the law of conservation of mass and played a critical role in recognizing oxygen as an element. His experiments revealed that iron, together with all other ferrous metals, reacts to oxygen by forming iron oxide or rust. If not for Lavoisier’s discovery, iron (which makes up most of today’s man-made structures) would have not been utilized for applications where air exposure is involved.
Resisting Oxygen-Related Corrosion
Metals that do not contain iron usually resist corrosion with oxygen. The best example of this type of metal is copper and all of its alloys. Instead of forming rust when exposed to oxygen, copper forms a layer of greenish material known as patina. This layer does not affect the interior of the metal and rather encapsulates it to prevent further corrosion.
Alloys of copper, such as brass and bronze, exhibit this property as well. In most cases, they resist corrosion caused by even more potent substances, including saltwater and certain acids. They also hold up to extreme temperatures, which explains why most manufacturers prefer them for making machine parts. It’s no wonder reliable bronze and brass suppliers make so much fortune.
Brass and bronze are alloyed with other metals to form even stronger and more corrosion-resistant metals. Muntz metal, a type of alpha-beta brass, for instance, is used for making cover plating for ships due to its high tolerance to saltwater corrosion. This type of brass resists fouling, too. Another popular example is silicon bronze, which essentially is bronze combined with a little bit of silicon. This metal is almost if not stronger than steel, making it a good material for making pumps and boilers or for applications where the strength of steel is needed but not its weakness to rusting.
Other Substances that Can Trigger or Accelerate Corrosion
Oxygen is not the only element that can trigger or accelerate corrosion. In fact, any solid, liquid, or gas substances can cause corrosion depending on the metal exposed to them. Acids (such as sulfuric acid, nitric acid, and hydrochloric acid) and bases (such as sodium hydroxide and potassium hydroxide) are also notorious for corroding many different types of alloy.
Some metals could also corrode when exposed to dehydrating agents, such as phosphorus pentoxide or calcium oxide; halogens and halogen salts, such as bromine and sodium hypochlorite; organic halides; and acid anhydrides.
Using Corrosion to Your Advantage
There’s no denying the destruction corrosion can bring to one’s project. If left unchecked, it can lead to construction failure, consequently endangering people’s lives. However, it does not always have to be viewed negatively. There are certain applications for which it can be beneficial, such as furniture making and metal disposal.
It takes many years for bronze to achieve a kind of patina that gives it an antique look. For those who sell bronze furniture and believe that lost time is lost money, however, waiting that long is outright counterproductive. This is why they resort to a process called patination in which they speed up the formation of patina. It involves controlled exposure of bronze to a certain corrosive substance until the beautiful brown and green color, which usually takes years to produce, emerges in a few days.
Working with metals, especially for projects that require stability and strength among other critical properties, is a high risk. You have to be able to tell which metals corrode to which substances first. It would be better, though, to use metals that you know won’t succumb to corrosion that easily. Why not go to a trusted copper sheet supplier like Rotax Metals and ask what specific types of metal supplies you need. They specialize in all kinds of copper alloy, and so you will definitely find the materials you need and get the value for your money in the end.
Chemistry of Oxygen (Z=8), chem.libretexts.org
Corrosion 101: What Is Corrosion?, eoncoat.com