CERAMICS

Ceramics once referred purely to pottery and to articles made by firing materials extracted from Earth.

 Ceramics are generally thought of as inorganic and nonmetallic solids with a range of useful properties, including very high hardness and strength, extremely high melting points, and good electrical and thermal insulation.

The best-known ceramics are pottery, glass, brick, porcelain, and cement.

What are ceramics?

Ceramic a nonmetallic and inorganic solid is so broad that it covers a much wider range of materials. 

 Ceramics include simple materials such as graphite and diamond, made up from different crystalline arrangements of the element carbon.

Complex crystals of yttrium, barium, copper, and oxygen make up the advanced ceramics used in so-called high-temperaturesuperconductors (materials with almost no electrical resistance)

Ceramics

ALUMINA SILICON CARBIBE SILICON NITRIDE ZIRCONIA SAPPHIRE

Types of ceramics

ALUMINA:

It offers very good performance in terms of wear resistance, corrosion resistance and strength at a reasonable price.

Alumina is the most widely used advanced ceramic material. Its high dielectric properties are beneficial in electronic

products. Armor, semiconductor processing equipment parts, faucet

disc valves, seals, electronic substrates and industrial machine components

Applications

Silicon nitride exceeds other ceramic materials in thermal shock resistance.

It also offers an excellent combination of low density, high strength, low thermal expansion and good corrosion resistance and fracture toughness.

Various aerospace and automotive engine components, papermaking machine wear surfaces, armor, burner nozzles and molten metal processing parts.

SILICON NITRIDE

Silicon carbide has the highest corrosion resistance of all the advanced ceramic materials.

It also retains its strength at temperatures as high as 1400°C and offers excellent wear resistance and thermal shock resistance.

Applications include armor, mechanical seals, nozzles, silicon wafer polishing plates and pump parts

SILICON CARBIDE

Zirconia has the highest strength and toughness at room temperature of all the advanced ceramic materials.

The fine grain size allows for extremely smooth surfaces and sharp edges.

Applications include scissors, knifes, slitters, pump shafts, metal-forming tools, fixtures, tweezers, wire drawing rings, bearing sleeves and valves.

ZIRCONIA

Single crystal sapphire offers superior mechanical properties and chemical stability coupled with light transmission.

Applications include GaAs carrier plates, POS scanner window, microwave plasma tubes and windows, fixtures for high temperature equipment and blue LED.

SAPPHIRE

They are of two types TRADITIONAL CERAMICS  include clay products, silicate glass and

cement.

ADVANCED CERAMICS  consist of carbides (SiC), pure oxides

(Al2O3), nitrides (Si3N4), non-silicate glasses and many others.

CLASSIFICATION OF CERAMICS

In general, advanced ceramics have the following inherent properties:

Hard (wear resistant) Resistant to plastic deformation Resistant to high temperatures Good corrosion resistance Low thermal conductivity Low electrical conductivity

USES OF ADV.CERAMICS

Aerospace: space shuttle tiles, thermal barriers, high temperature glass windows, fuel cells

Consumer Uses: glassware, windows, pottery, Corning¨ ware, magnets, dinnerware, ceramic tiles, lenses, home electronics, microwave transducers

Automotive: catalytic converters, ceramic filters, airbag sensors, ceramic rotors, valves, spark plugs, pressure sensors, thermistors, vibration sensors, oxygen sensors, safety glass windshields, piston rings

CERAMICS & ITS VARIOUS USES

Medical (Bioceramics): orthopedic joint replacement, prosthesis, dental restoration, bone implants

Military: structural components for ground, air and naval vehicles, missiles, sensors

Computers: insulators, resistors, superconductors, capacitors, ferroelectric components, microelectronic packaging

Other Industries: bricks, cement, membranes and filters, lab equipment

Communications: fiber optic/laser communications, TV and radio components, microphones

However, some ceramics exhibit high thermal conductivity and/or high electrical conductivity.

The combination of these properties means that ceramics can provide:

High wear resistance with low density Wear resistance in corrosive environments Corrosion resistance at high temperatures