Ceramics

Philip signed up for a pottery class, and this is his first project. He uses wet clay, which is soft and moldable, and he shapes it into a plate. Once Philip's happy with the shape of his plate, he puts it into a special hot oven, called a kiln. The heat dehydrates and hardens the clay, turning it into ceramic. Humans have been making ceramics this way for thousands of years.

In the last few hundred years, we’ve developed new ways of making ceramics, too. Today, ceramics is a very broad term that refers to many solid, human-made materials. In material science, ceramics are defined as a group of materials that are non-metallic and inorganic. This means that chemically they are not metals, and they do not contain carbon-based organic compounds. But they might contain atoms of metallic elements or carbon.

In fact, many ceramics are compounds of a metallic element, for instance aluminium or magnesium, combined with another non-metallic element, such as oxygen, carbon, or nitrogen. Many types of ceramics are made from naturally occurring raw materials, such as different types of clay and minerals. Ceramics are manufactured by mixing and shaping raw materials, and then heating them up to a very high temperature. In this process of firing, atoms are rearranged, often forming a regular crystalline structure, and the material hardens. The chemical composition and structure of ceramics determine their properties.

Ceramics are generally very hard and stiff. That makes them good for many different applications, from industrial tools, to mugs and plates. At the same time, ceramics might be very brittle. Ceramics are also great as building materials, for example in bricks and roof tiles. This is because ceramics are strong and withstand compressive forces very well, so they can carry large weight.

They can also withstand harsh conditions, because they do not corrode easily, most are easily penetrated by water — they are porous. But these are often covered with glaze before firing. This creates a water-resistant coating, like the one on kitchenware or bathroom tiles. Ceramics are also heat-resistant, and have a very high melting point. For this reason, many pans and baking dishes are ceramic.

In fact, ceramics can withstand temperatures much higher than temperatures inside a regular oven. Ceramics are used in the protective shields of space shuttles to prevent them from burning up in the atmosphere. Most ceramics conduct electricity very poorly or not at all, so they are also often used in electrical insulation. But others are semiconductors. These types of ceramics are used to make parts for electronic devices.

Ceramics have gone a long way from simple fired clay objects to advanced engineering materials. And scientists and engineers continue to develop better ceramics and experiment with their different properties. Who knows what new exciting applications they will find in the future!