What is the difference between metals, ceramics, polymers, and composites?

Difference between Metals, Ceramics, Polymers, and Composites

Property	Metals	Ceramics	Polymers	Composites
Bonding	Metallic bonding (sea of electrons)	Ionic & covalent	Covalent + van der Waals	Combination (matrix + reinforcement)
Structure	Crystalline (FCC, BCC, HCP)	Crystalline / amorphous	Long-chain molecules	Mixture of 2+ materials
Strength	High strength & toughness	Very hard but brittle	Low strength, flexible	High strength-to-weight ratio
Density	High (heavy)	Medium to high	Low (lightweight)	Depends on constituents
Ductility	Ductile & malleable	Brittle	Flexible/elastic	Can be tailored
Conductivity	Good conductor (heat & electricity)	Poor conductor (insulators)	Poor conductor	Depends on matrix (e.g., CFRP may be conductive)
Corrosion resistance	Prone to corrosion (unless treated)	Excellent	Excellent	Good (depends on constituents)
Melting point	High	Very high	Low	Depends on constituents
Examples	Steel, Aluminum, Copper	Glass, Porcelain, Alumina	PVC, Nylon, Teflon	Concrete, Fiberglass, Carbon Fiber
Applications	Construction, machinery, vehicles	Bricks, ceramics, insulators	Plastic goods, textiles, medical devices	Aircraft, sports equipment, automotive, buildings

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✅ Short Exam Revision (3–4 lines):

• Metals → Strong, ductile, and good conductors.

• Ceramics → Hard, brittle, high-temperature resistant, electrical insulators.

• Polymers → Lightweight, flexible, corrosion-resistant, poor conductors.

• Composites → Combination of materials giving tailored, high strength-to-weight properties.

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