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Science Materials Science & Engineering

Ceramics

Grey concrete surface

All of us have dropped drinking glasses and mugs before and seen them break into many pieces on the floor. This begs the question: how can such brittle materials be used in engineering? Ceramics have been used in civil structures for centuries. They are used in many ancient structures that have survived to the present day - the great pyramid of Giza, the great Wall of China. These structures show that ceramics are very resistant to corrosion and wear, and can be used in many applications, even though they may be brittle.

Introduction

All of us have dropped drinking glasses and mugs before and seen them break into many pieces on the floor.

Structure and form

Before we discuss ceramics and their structures it may be useful for you to review theory on atomic bonding.

Ceramic types

Many common ceramics such as bricks and tiles are based primarily on clay. These are pressed or extruded into shape while in a wet plastic state and then dried and fired.

Properties

In this section we will consider the typical properties of ceramics. Ceramics are typically hard and brittle. While their strength in compression is very high, they are not suitable for loading in tension.

Glass

Glasses are a unique range of ceramic materials defined principally by their atomic structure. Glasses do not exhibit the ordered crystalline structure of most other ceramics but instead have a highly disordered amorphous structure. This gives them very different properties to other crystalline ceramics.

Concrete

Concrete is the most widely abundant engineering material in the world today in terms of volume used. Concrete is not officially a ceramic but is rather a composite made up of sand, aggregate, and cement. With the addition of water the cement reacts to form a ceramic like structure around the sand and aggregate particles.

Forming methods

We have already seen a few of the principle processes that are involved in forming glass products. Of equal significance, however, is the fabrication of crystalline ceramic products.