Please enable JavaScript.
Coggle requires JavaScript to display documents.
Classification of Materials - Coggle Diagram
Classification of Materials
Ceramics
Definition
Inorganic, non-metallic
Metal + non-metal elements
Composition
Common non-metals: O, N, C
Compounds
Oxides (Al₂O₃, ZrO₂)
Nitrides (Si₃N₄)
Carbides (SiC)
Properties (from bonding)
High hardness & melting point
Excellent chemical resistance
Brittle, poor conductors
Structure
Atoms tightly bonded
Limited atomic movement
Forms
Crystalline
Non-crystalline (glassy)
Partially crystalline (glass-ceramics)
Crystalline ceramics
Unit cell → crystals
Grain structure
Grains + grain boundaries
Small grains → ↑ strength
Large grains → ↑ brittleness
Bonding
Ionic bonding
Electron transfer (e.g. NaCl)
Covalent bonding
Electron sharing (e.g. SiC)
Mixed ionic–covalent
Common in ceramics
Example: Hydroxyapatite
Metals
Definition
Elements that donate electrons
High strength, ductility, conductivity
Types
Noble metals
Corrosion resistant
Gold, Palladium, Platinum
Base metals
Higher corrosion tendency
Ni, Cr, Cu, Zn, Be, Ag
Composition
Metallic elements
Fe, Al, Cu, Au, Ti, Ni
Non-metallic elements (minor)
C, O, N, S
Modify strength, hardness, ductility
Structure
Crystalline structure
Ordered atomic arrangement (lattice)
Unit cell
Smallest repeating unit
Crystal types
FCC → high ductility (Al, Cu, Au)
BCC → high strength (Fe, Cr)
HCP → strong, low ductility (Ti, Zn)
Grain structure
Polycrystalline
Grain boundaries affect strength & corrosion
Small grains → ↑ strength (Hall–Petch)
Bonding
Metallic bonding
Positive ions + sea of electrons
Explains conductivity & deformability
Composites
Definition
Multi-phase materials
Combine properties of different materials
Composition
Resin matrix
Polymerizable organic base
Fillers
Silica, quartz, glass, zirconia
↑ strength, ↓ shrinkage
Coupling agent
Silane
Bonds filler ↔ resin
Initiators
Light-activated polymerization
Pigments & stabilizers
Structure
Polymer matrix = continuous phase
Fillers dispersed in matrix
Filler size & distribution affect:
Strength
Wear resistance
Shrinkage
Bonding
Covalent → resin matrix
Ionic/covalent → fillers
Covalent via silane coupling agent
Secondary bonds between polymer chains
Polymers
Definition
Large organic molecules
Made of repeating monomers
Composition
C, H, O, N
Dental examples
PMMA
Composite resin matrix
Adhesives
Structure
Long covalently bonded chains
Carbon–carbon backbone
Chains are flexible (coils, bends)
Molecular architecture
Linear
Flexible, thermoplastic
Example: PMMA
Branched
Lower density, more flexible
Cross-linked
Stiffer, stronger
Dental composites
Network
Highly cross-linked
Thermoset (resin cements)
Chain configuration
Isotactic
Syndiotactic
Atactic
Cis–trans
Solid-state structure
Amorphous regions
Crystalline regions
Mostly semicrystalline
Bonding
Primary
Covalent (within chains)
Secondary
Van der Waals
Hydrogen bonding
General properties
Lightweight
Moldable
Low strength vs metals/ceramics