1. Primary Chemical Components
Most ceramics are based on metal oxides, carbides, nitrides, or silicates. Common elements include:
* Oxygen (O) – Found in oxides (e.g., Al₂O₃, SiO₂, ZrO₂).
* Silicon (Si) – Key in silicates (e.g., clay, mullite, cordierite).
* Aluminum (Al) – Present in alumina (Al₂O₃), mullite (3Al₂O₃·2SiO₂).
* Magnesium (Mg) – Used in magnesia (MgO), cordierite (2MgO·2Al₂O₃·5SiO₂).
* Zirconium (Zr) – Found in zirconia (ZrO₂).
* Carbon (C) & Nitrogen (N) – In non-oxide ceramics (SiC, Si₃N₄, TiC, BN).
2. Traditional Ceramics (Clay-Based)
These are typically silicate-based and include:
* Clay minerals (Kaolinite, Montmorillonite) – Provide plasticity when wet.
* Silica (SiO₂) – Adds structure (e.g., quartz, flint).
* Feldspar (KAlSi₃O₈, NaAlSi₃O₈) – Acts as a flux to lower melting temperature.
* Chalk (CaCO₃) – Used in porcelain and whiteware.
Example: Porcelain = Kaolin (clay) + Silica + Feldspar.
3. Advanced (Engineering) Ceramics
These are high-purity, synthetic ceramics with superior properties:
Ceramic Type Main Components Key Properties
Alumina (Al₂O₃) Aluminum + Oxygen High hardness, electrical insulation
Zirconia (ZrO₂) Zirconium + Oxygen High toughness, wear resistance
Silicon Carbide (SiC) Silicon + Carbon Extreme hardness, thermal conductivity
Silicon Nitride (Si₃N₄) Silicon + Nitrogen High strength, thermal shock resistance
Boron Nitride (BN) Boron + Nitrogen Lubricity, thermal conductivity
Cordierite (2MgO·2Al₂O₃·5SiO₂) Mg, Al, Si, O Low thermal expansion
4. Additives & Secondary Components
Ceramics often include additives to modify properties:
* Binders (e.g., PVA, wax) – Help in shaping before firing.
* Sintering Aids (e.g., Y₂O₃ in ZrO₂) – Enhance densification.
* Pigments (e.g., Fe₂O₃, CoO) – For coloration.
* Porosity Controllers – To create porous ceramics (e.g., filters).
5. Glassy Phase (in Some Ceramics)
* Traditional ceramics often contain a glassy phase (vitreous silica) formed during firing, which bonds particles together.
6. Classification by Composition
Category Examples Main Components
Oxide Ceramics Al₂O₃, ZrO₂, MgO Metal + Oxygen
Non-Oxide Ceramics SiC, Si₃N₄, TiN Metal + Carbon/Nitride
Silicate Ceramics Porcelain, Brick Clay + SiO₂ + Flux
Composite Ceramics Al₂O₃-SiC, ZrO₂-toughened Mixed ceramics
Conclusion
Ceramics are made from a combination of metallic and non-metallic elements, with their properties determined by composition and processing.
* Traditional ceramics rely on clay, silica, and feldspar.
* Advanced ceramics use high-purity oxides, carbides, or nitrides for superior performance.
