Rusting can cause an array of problems. They range from producing cracks and holes in metals to reducing metals’ magnetic properties and electrical or thermal conductivity.
Although rust is non-toxic, its presence in infrastructures can jeopardize our safety. It affects things such as bridges and cars. Since it is a natural phenomenon, all metals containing iron must be regularly checked to avoid any safety hazards.
| Materials we’ll take a closer look at | ||
| Brass | Zinc | Sterling silver |
| Tin | Titanium | Wrought iron |
| Lead | Powder-coated steel |
Summary
Because it doesn’t contain iron, brass does not rust. You will find out that Zinc doesn’t rust either, but this process will occur once other alloys are added. Tin doesn’t rost, and is often used to coat metal used for food storage.
Table of Contents
Brass
Brass is an alloy of copper and zinc, with the former usually being the main component. Depending on the proportions of copper and zinc, the color may change from bright gold up to reddish-gold or silver. Other elements may also be added depending on what is needed, non-metal or metal.
Copper is extremely ductile and has a high thermal and electrical conductivity, but it is soft and malleable by itself. The addition of zinc improves the strength and flexibility of the brass.
The resulting alloy has a low melting point and high workability and durability. It’s the perfect material for musical instruments and decorative items. It’s also great for plumbing and locks.
Brass does not contain iron unless it is an added component for certain applications. It is usually added at a very low concentration of iron, so it isn’t very important. Therefore, it does not rust.
However, brass does corrode and oxidize! The resulting oxide isn’t iron oxide, so you cannot classify it as rust. It’s more suitable to call it tarnish.
Here’s one example of how it corrodes: Selective leaching.
When the zinc in brass leaches off, it is called dezincification. And when zinc is lost, the alloy weakens because zinc is the one that contributes to the durability/strength. Copper is left behind. If copper is the one that leaches off, it’s called decuprification. Either way, the structural integrity of brass will be compromised.
Dezincification is more common since zinc is more reactive than copper. Once this happens, pink or reddish discoloration on brass appears. Exposure to moisture or water will also quicken this type of corrosion since the zinc will oxidize faster.
In musical instruments, the dezincification occurs in areas where the instruments were held. It’s caused by sweat as the source of moisture. Musicians call this phenomenon “red rot.”
What is the blue-green layer that forms on it?
Although this phenomenon is also caused by oxidation, the blue-green layer you see on brass is not a sign of corrosion! It’s called patina, a naturally-occurring film layer on most metals.
The patina is not detrimental to the alloy—it may become a shield against air and moisture. Many people even consider this color change attractive on brass. Some accelerate the oxidizing process by applying solutions for an “aged/vintage look.”
Zinc
Zinc is mostly used to galvanize steel, applied as a coating that’s metallurgically bonded to the steel. It protects it from corrosion like oxidation or rusting. Zinc acts as a sacrificial metal, reacting with oxygen to form a zinc oxide layer that prevents rusting or the formation of iron oxide.
By itself, zinc is pretty weak and brittle. It has low to moderate tensile strength and conductivity. The resulting alloy usually has high impact strength when alloyed with other metals. It also has ductility and is more corrosion-resistant.
Zinc itself doesn’t rust, but the process may occur if alloyed with iron or ferroalloys. Also, suppose the zinc layer of galvanized steel is compromised. It may occur since the underlying material that contains iron will be exposed to air and water.
| Property | Value |
| Atomic Mass | 65.38 g/mol |
| Atomic Number | 30 |
| Boiling Point | 907°C |
| Classification | Metal |
| Density | 7.14 g/cm³ |
| Discovered | 1746 |
| Electronic Configuration | [Ar] 3d10 4s2 |
| Group | 12 |
| Melting Point | 419.53°C |
| Period | 4 |
| Phase at Room Temperature | Solid |
| Symbol | Zn |
Titanium
Titanium is a strong, lustrous, and corrosion-resistant metal. Its high corrosion resistance is due to its ability to form titanium dioxide upon oxidation. Its strong oxide layer protects the titanium metal underneath from corrosion caused by most acids and saltwater.
Furthermore, other salts that would usually speed up the corrosion of some metals inhibits the corrosion of titanium. Like tungsten, titanium is one of the most durable natural metals. Despite being resistant to most corrosion-like oxidation, titanium isn’t immune to pitting and saltwater corrosion at elevated temperatures.
Titanium itself doesn’t rust. The commercially available forms of titanium are usually alloys. If iron is one of the alloy’s components, it can happen.
If you’re looking for a tool to cut this strong metal, oxy torches or plasma cutters can still do the job. But if you’re dealing with metals that are not as tough as titanium or tungsten, these engine-driven welders will be perfect for you.
| Property | Value |
| Atomic Mass | 47.87 g/mol |
| Atomic Number | 22 |
| Boiling Point | 3,287 °C |
| Classification | Metal |
| Density | 4.51 g/cm³ |
| Discovered | 1791 |
| Electronic Configuration | [Ar] 3d2 4s2 |
| Group | 4 |
| Melting Point | 1,668 °C |
| Period | 4 |
| Phase at Room Temperature | Solid |
| Symbol | Ti |
