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Material Category:

Ceramics & Glasses

Category Summary

Ceramic is one of the four traditional material classes in material science. The other classes being composite, metal and polymer. This class of materials contains materials with a wide range of compositions, which results in only little shared characteristics and properties. Ceramics in general are very stable and can withstand the elements, high temperature, acidic or caustic environments and are very corrosion resistant. Therefore they are fit for a wide range of applications, like construction, heating or melting, chemical processing, food storage or medical implants.

Category Details

Features

In general ceramics share the following properties:

  • Hard
  • High compressive strength
  • Able to withstand high temperatures
  • Very good resistance to acidic or caustic environment

But keep the following in mind:

  • Brittle (although some ceramics can be transformed into tough materials)
  • Weak tensional strength
  • Weak flexurial strength
  • Weak resistance against shear stress
  • Limited machinabilty
  • Limited forming capabilities
  • Limited bonding capabilities

Classification

Ceramics and glasses are inorganic, non-metallic solid materials. The elements carbon and silicon may also be considered ceramics. Man-made ceramics are created by heating compounds of metallic and non-metallic materials, followed by cooling.

Based on their molecular structure 3 types of ceramics can be distinguished:

Crystalline ceramics

The largest part of ceramics have a crystalline structure. The options to process crystalline ceramics are very limited. In most cases the ceramic is kept in a mold after which a chemical reaction is invoked to create a solid body, another common way to create this solid body is to force ceramic powders into the desired shape and heating this shape below its melting temperature and the powders start to bond. This process is called sintering. A combination of these processes is also possible. Most crystalline ceramics are very hard and brittle and therefore machinability is very limited.

Non-crystalline ceramic

Ceramics with a non-crystalline or amorphous structure are generally referred to as glass. Glass can be created by completely melting a compound of metallic and non-metallic substances, pouring it in the desired shape and then cool it it down to form an amorphous ceramic solid. This method is mostly used for glass sheets or panes. Another way glass can be created is by heating a compound until it reaches a certain level of viscosity and can be manipulated in the desired shape and then cooled down to solidify and form glass. In many cases the workpiece needs to be reheated or kept at the right temperature while its being manipulated into the final shape.

Partly-crystalline ceramics

Amorphous ceramics (glass) can be (heat) treated to create a partly crystalline structure. For this reason the term ceramic glass is very common.

Raw material

Ceramic raw material is available as powder, granulae, chippings or clay.

Classification Sources

Idemat 2003

Wikipedia

Health

Known health effects for this category.

Toxicity

There is no data available on this level

Environment

Known environmental effects for this category.

There is no data available on this level