Ceramics

Production processes firstly involve thoroughly blending the very fine constituent material powders. After shaping them into a green body, this is high-temperature fired (1,600–1,800°C). This step is often carried out in an oxygen-free atmosphere.

The high temperature allows the tiny grains of the individual ceramic components to fuse together, forming a hard, tough, durable and corrosion-resistant product. This process is called sintering.

The common ceramic we find in the sealing industry includes:

• 95: meaning 95% aluminum oxide with the balance mainly silica.
• 5: meaning 99.5% aluminum oxide with no silica. A small amount of caesium is added to control the grain size and improve the firing characteristics.

Ceramic is a versatile seal face material that is generally inexpensive. It is a hard material & light to touch, with a white color. Ceramic offers excellent wear characteristics & chemical compatibility. Unlike other mechanical seal face materials though, it cannot handle thermal shocks. Ceramics retain heat when equipment is not operating, and general start-up procedures can easily crack this seal face material. Ceramic, like silicon carbide, will shatter/crack if contacted with force or dropped.

Classification of Ceramics are based on their:

• Oxides,
• Carbides,
• Nitrides,
• Sulfides,
• Fluorides