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Materials Classification
Basic on chemical makeup and atomic 
structure, solid materials grouped into four 
basic classifications:
– Metals
– Ceramics
– Polymers
– Composite (two or more of the above 3 classes)
Metals
Metals
• Usually combinations of metallic elements
• Atoms are arranged in a very orderly manner
• Large number of nonlocalised electrons
• Many properties are attributable to these 
electrons
• Good conductors of electricity and heat
• Strong yet deformable
Examples: aluminum, steel, brass, gold.
Ceramics
Ceramics
• Compounds between metallic and non-metallic 
elements
– frequently oxides, nitrides, carbides
• Clays, Cement, Glass 
• Good heat and electricity insulators
• High temperature resistant
• Can withstand corrosive environments
• Hard and brittle
Examples: glass, porcelain, many minerals.
Polymers
Polymers
• Include plastics and rubber materials
• Organic compound chemically based on 
carbon, hydrogen and non-metallic elements
• Very large molecular structures
• Low densities 
• Very flexible
Examples: plastics (nylon, Teflon, polyester) 
and rubber
Composites
• Consist of more than one material type
• Designed to achieve a combination of the best 
properties of each of the component materials
• Wood, Bone, Fibreglass
– fibres are embedded in a polymeric matrix
– Fibreglass obtains its strength from the glass and 
the flexibility from the polymer
Density
Stiffness
Strength
Fracture Toughness
Advanced Materials
• Materials utilise in high-tech applications
• Traditional materials whose properties have been 
enhanced and newly developed, high performance
• Normally expensive
• Examples
– Electronic equipment
– Fibre-optical system
– Aircraft, spacecraft
– Military rocketry
• Semiconductors 
– Intermediate electrical properties between 
conductors and insulators
– Computer industries
• Biomaterials
– Implanted into the human body for replacement 
diseased or damaged parts
– Must not produce toxic substances
– Must be compatible with body tissues
• Smart materials
– Some type of sensor
– In helicopters to reduce aerodynamic 
cockpit noise that created by the rotating 
rotor blades
• Nanoengineered materials
– Carbon nanotube
Materials of the future
Why are the properties of some materials 
so different to that of other materials?
• Atomic Structure
• Crystal Structure
• Microstructure