UNIT1-2

UNIT1-2

1. The types of materials

   • Which materials we are going to use?
   • Should they be natural or man-made?
   • SELECTING MATERIALS
     • Raw materials
     • Funtion: creating a pleasing appearance
     • Durability: How long should the solution last?
     • Cost of materials: What is our budget
     • The kinds of additional elements that need to be included:Which tools must be used? Are joints needed?
     • The techiques to be used:CAn we learn the techniques we need to work with the materials and tools available to us in a reasonable period of time?

2. RAW MATERIALS

   • are products extracted directly from nature. They may be of plant,animal or mineral origin.Air and water are also considered raw materials and are essential for crops and life in general.

3. NATURAL AND PROCESSED MATERIALS

   • Industrial processes are applied in raw materials,also known as natural resources, to turn them into processed materials. a technological product is an object made using materials, designed by humans to meet a specifit need
   • the materials used to make more complex objects : the wood for trees is made in to planks, that we used to build furniture. Once the materials have been processed, they may be classified as either artificial or synthetic.

4. PROPERTIES OF MATERIALS

   • Mechanical properties
     • Hardness: resistance of a body to being pierced or scratched by another body
     • Mechanical resistance: ability of a body to resist the forces applied to it without breaking or changing in shape
     • Toughness; a body´s resistance to being changed, deformed or broken
     • Brittleness: ability of an object to break easily, without being deformed hardly at all
     • Elasticity: ability of a material to return to its original shape after being deformed under external forces after the stop
     • Plasticity: ability of a body to become permanently deformed without breaking, once its elastic limit has been exceeded
   • THERMAL PROPERTIES
     • Expansion: increase in size observed in a body when its temperature rises
     • Thermal conductivity: ability to transmit heat
   • ENVIRONMENTAL PROPERTIES
     • Toxicity: how strong a poison or toxin is
     • Environmental hazard: level of toxic effect a contaminant has on an ecosystem
     • Recyclability: possibility of reusing a material for either the same purpose it was made for or a different one
     • Biodegradability: a material´s ability to naturally decompose