MATERIALS

MATERIALS

1. RAW MATERIALS

   • Classified in three groups:Animal, vegetable and mineral origins.
     • Examples:Cotton->Plant origin Wool->animal origin Clay->Mineral origin

2. MATERIALS

   • Raw materials are transformed by phisical and chemical processes to be materials
     • Physical process
       • Is when a substance changes its state.The chemical composition doesn't change
     • Chemical process
       • Is when a substance is transformed into a different substance with different characteristics

3. MANUFACTURED GOODS

   • Are objects created by humans to satisfy their needs.
     • The manufacturing process
       • 1.We get raw materials from nature 2.We process them to make materials 3.We make goods with these materials
         • Trees->Logs->Planks of wood->Furniture

4. Properties of materials

   • Physical properties
     • How materials react to stimuli
       • Electrical properties
         • Electrical conductivity
           • Some materials conduct electricity. E.g.:metals
         • Electrical insulation
           • Some materials don't conduct electricity.E.g.:plastic
       • Thermal properties
         • Thermal conductivity
           • Thermal conductors are materials that conduct heat
           • Thermal insulators are materials that don't conduct heat
         • Expansion and contraction
           • When the temperature increases,the material expands.When it decreases the material contracts
         • Fusibility
           • When the temperature of a material increases and its state changes to solid
         • Welding
           • Some materials can be used to weld (soldatu) of the same or different materials together
       • Acoustic properties
         • Acoustic conductivity
           • The capacity of a material to transmit sound
         • Acoustic insulators
           • Materials that don't transmit sound
       • Optical properties
         • Opaque
           • Other objects can't be see trough them
         • Translucent
           • Allows light pass trough them but doesn't allow seen objects clearly
         • Transparent
           • Objects can see clearly trough these objects