Metals: Properties, Processing and Applications
Introduction to Metals
The Greek word “metallon” can be translated as “to extract” or mine from the ground. The earth’s crust does indeed contain plenty of metal. In fact, out of the 118 elements on the periodic table, three-quarters of them are metallic. Even some of the remaining elements share some characteristics with metals and are therefore referred to as semi-metals or metalloids.
The first metal to ever be discovered by mankind was copper, followed by lead, gold, silver, and tin in the millennia that followed. Today, metals are classified into several sub-groups, among them are:
- alkali metals
- alkaline earth metals
- transition metals
- post-transition metals
- lanthanides
- actinides
Characteristics of Metals
All the elements classified as metals have the following in common:
- generally opaque, silver-gray in color (with a few exceptions like gold and copper) and shiny.
- cold to touch, solid at room temperature (with the exception of mercury, a liquid) and have a high melting point.
- strong, crystalline, ductile, dense, malleable, sonorous, and they conduct heat and electricity well.
- react readily to exposure with other elements, including oxygen, which makes metals difficult to extract in their pure form from the earth’s crust.
Their chemical properties can, however, prove extremely useful in all manner of metal applications.
Production and Processing
In pure form, metals can be hard to come by – they are often buried in ore together with other metal deposits.
Metals must firstly be extracted and then refined. Large metal deposits are mined all around the world, for example, India boasts the world’s largest zinc mine, bauxite is found in abundance in countries with tropical climates, and China mines most of the world’s titanium.
Ore is extracted from the ground and refined to isolate the metal from other compounds, and then the metal is exposed to chemical, heat and/or electrical treatment.
A metal that is combined (usually melted together) with other materials is called an alloy, and here, the application possibilities are endless.
Uses
You’ll find metal just about anywhere you look, either in pure form or as an alloy. The creation of alloys has led to the ability to customize metal production for many thousands of purposes.
Structural alloys, for example, can withstand extremely large loads and repeated impact, which is why they are used to construct roads, bridges and buildings, and form parts of vehicles and aerospace applications.
Metals are also used to make tools, cables, wiring, appliances, utensils, protective coatings, packaging, ornaments, and medical equipment.