2: Traditional Ceramics
Traditional ceramics are comprised of three basic components - clay, silica (quartz), and feldspar.
Clay is one of the most common ceramic raw materials. It is used widely because it is found in great quantities naturally and it is easily formed. Clay is used in structural clay products (bricks, pipes, tiles) and whitewares (pottery, tableware, china, sanitaryware). Clay makes up the majority of the ceramic body and is primarily composed of hydrated aluminium silicates, Al2O3.SiO2.H2O. Most clay products also contain an inexpensive filler, often quartz, and a feldspar, or flux, that forms a glass to bind ceramic particles during heat treatment.
The workability of clays is derived from the plate-like shape of their particles. Each particle is electrically charged on its surface. This electric charge attracts water molecules that sit between the surfaces of adjacent clay particles. When the clay is formed or moulded the water acts as a lubricating layer between the plate-like particles allowing them to slide over one another with very little friction while also maintaining an atomic bridge between the plates to hold them together.