Ceramics

Material Ceramics

Ceramics are generally characterized by a crystalline structure and an ionic bond of the atoms. The difference in the atomic bonding distinguishes them from metals, and their inorganicity from organic materials (plastics, rubbers and wood).
Most ceramics are metal oxides.

In general they are very stiff, hard but brittle, have low densities, high melting temperatures, high heat resistance, are electrical insulators, chemical and ageing resistant.

There are a number of shaping processes for ceramics, but all ceramic materials need to be sintered.

Traditional ceramics

Ceramic type	Price (DKK/kg)	Density (kg/liter)
Earthenware	-	-
Stoneware	-	-
Porcelain	-	2,5
Faience	-	-

Technical ceramics

Ceramic type	Price (DKK/kg)	Density (kg/liter)
Aerogels	(100,000)	(0.3)
Carbide, Silicon	150	3.2
Carbide, Titanium	350	4.93
Carbide, Tungsten	480	15.63
Glass-bonded mica	-	-
Nitride, Al	750	3.26
Nitride, Bo	1,200	2.28
Nitride, Si	100-700	3.44
Oxide, Al	80-160	ca. 4
Oxide, Be	-	2.87
Oxide, Mg	80-130	3.58
Oxide, Ti	35	4.26
Oxide, Zr	160-240	5.6
Telluride, Bi (thermoelectric)	-	7.7
Titanate, Al	-	3.15

Environ- mentals notes Disposal: Incineration of ceramics with high concentrations of heavy metals (e.g. lead) significantly contributes to air emissions or ash toxicity (because heavy metals volatilise from the material.)
Therefore they are rather recycled and reused.

Price Price level 2004.
Price sources are whole sale shops and the internet site of Atlantic Equipment Engineers.

These prices are only meant as guiding figures for the purchase of common powders and in industrial quantities (i.e. > 50 kg).
Prices vary significantly for different material purities and types (powder, granulate, etc.). In fact, for small amounts (from 1 g up to 1 kg) of high-tech ultra-pure raw ceramic materials, prices can be very high (up to thousands of DKK/kg.)

References Links:
Kyocera
M.O.Knudsen's Eftf.

Books:
A Concise Introduction to Ceramics
Ceramic Matrix Composites
Introduction to Fine Ceramics
Introduction to Powder Technology
Modern Ceramic Engineer
Keramisk Håndbog

For materials in general see also:
Machine Design On-line
Materials by Design

Photo Thomas Nissen (Computer graphics)