Ceramics and Composite Materials
Ceramics cover a very wide range of materials from structural materials like concrete to technical ceramics like PZT – a piezoelectric. Usually they are defined as solids with a mixture of metallic or semi-metallic and non-metallic elements (often, although not always, oxygen), that are quite hard, non-conducting and corrosion-resistant. The most useful technique for finding the composition of a ceramic is energy dispersive x-ray spectroscopy (EDS). Ceramics are mostly made by powder processing techniques, for example sintering. Composites are often used in applications that require specific ‘conflicting’ properties such as a high strength and high toughness. The properties may be conflicting because having a high yield stress sometimes relies on trapping and tangling dislocations, but these reduce the ductility and toughness of the material. Composites often consist of a matrix and fibres or particles that affect the properties.