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Categories of Materials

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Categories of Materials Organics Metals and Alloys Polymers or Plastics Ceramics Composites Organics Organics are or were living organisms Composed of mostly ... – PowerPoint PPT presentation

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Title: Categories of Materials


1
Categories of Materials
  • Organics
  • Metals and Alloys
  • Polymers or Plastics
  • Ceramics
  • Composites

2
Organics
  • Organics are or were living organisms
  • Composed of mostly carbon and Hydrogen
  • Structure depends on the way cells develop, not
    by human manipulation
  • Renewable, sustainable
  • Infinite variety
  • Genetically alterable

3
Organics-Wood
  • Hardwood- Deciduous, tend to be harder and more
    expensive
  • Softwood- Conifers, tend to be softer and cheaper
  • Plywood- Much stronger and dimensionally stable
  • Engineered Beams- Construction only
  • Oriented Strand Board and MDF- Dimensionally
    stable and cheap

4
Metals and Alloys
  • Metals are pure elements which comprise about
    three-fourths of the periodic table
  • Few are used in their pure form because of
  • Hardness too hard or too soft
  • Cost scarcity of element
  • Engineers need certain characteristics that can
    only be accomplished by a blending of elements
  • Metals are malleable, reflective, and
    electrically conductive material
  • They are excellent conductors of electricity and
    heat

5
Metals
  • Possess material properties, including
  • high strength and toughness
  • high electrical conductance
  • high thermal conductance
  • luster
  • Examples
  • aluminum - copper - gold - zinc - iron - lead -
    nickel
  • silver - thorium - chromium - tin - beryllium

6
Alloys
  • Consist of materials composed of two or more
    elements, at least one being a metal
  • This combination of elements gives the material a
    combination of properties from each element
  • Examples
  • Steel- iron, carbon and impurity elements such as
    boron copper or silicon
  • Brass - copper, zinc
  • Stainless Steel - nickel,iron
  • Monel - nickel,copper

7
Types of Metallics
  • Ferrous Metallics - iron and alloys which contain
    at least 50 iron (e.g. wrought iron, cast iron,
    steel, stainless steel)
  • Nonferrous Metallics - Metallic elements other
    than iron (e.g. copper, lead, tin, zinc,
    titanium, beryllium, nickel)
  • Powdered (Sintered) Metals (ferrous or
    non-ferrous)
  • Sometimes called sintered metal. A process of
    producing small (powdered) particles which are
    compacted in a die and then sintered (applying
    heat below the melting point of the main
    component)
  • Examples

    trigger on gun, gears, bearings,
    carbide tool inserts

8
Polymers
  • Polymers
  • Chain-like molecule made of many (poly) smaller
    molecular units (monomers)
  • Chaining (polymerization) is responsible for the
    formation of natural fibers, wood, lignin,
    rubber, skin, bone and the tissues of animals,
    humans and insects

9
Plastics
  • Plastics
  • Human-made polymers
  • Plastics are workable or moldable
  • Thermosetting plastics are formable once (e.g.
    epoxy, phonelic (Bakelite), polyurethane)
  • Thermoplastics can be heated repeatedly and
  • formed into new shapes (e.g. polyethylene,
    nylon, Plexiglas)

10
Elastomers
  • Elastomer
  • amorphous (shapeless) structure consisting of
    long coiled-up chains of entangled polymers
  • can be stretched at room temperature to at least
    twice its original length and return to its
    original shape after the force has been removed
  • Process to strengthen an elastomer vulcanization
  • a chemical process used to form strong bonds
    between adjacent polymers to produce a tough,
    strong, hard rubber (automobile tires)

11
Ceramics
  • Crystalline compounds combining metallic and non
    metallic elements
  • The absence of free electrons make ceramics poor
    electrical conductors.
  • Because of the strength of the bonding, ceramics
    have high melting temperatures

12
Ceramics(continued)
  • Categories
  • Clay
  • Refractory
  • Electrical and Magnetic
  • Glasses
  • Cermets

13
Ceramics(continued)
  • Clay Products
  • Inorganic material which is shaped, dried and
    fired.
  • Examples brick, floor and wall tiles, drainage
    tile, roof tile, sewer pipe, chimney flue, china,
    and porcelain.

14
Ceramics(continued)
  • Refractory Materials
  • Ceramics designed to provide acceptable
    mechanical or chemical properties while at high
    temperatures.
  • Most are based on stable oxides such as carbides,
    nitrides, and borides.
  • An example of a refractory is the machinable
    all-silica insulating tiles on the U.S. space
    shuttle

15
Ceramics(continued)
  • Electrical and Magnetic Applications
  • Ceramics are used as resistors and heating
    elements for furnaces (silicon carbide)
  • Semiconductor properties
  • Thermistors- as they heat-up allow current to
    flow.
  • Rectifiers- allow current to flow in one
    direction
  • Clay based ceramics for high-voltage insulators

16
Ceramics(continued)
  • Glass
  • Based on silica with additives that alter the
    structure or reduce the melting point, optimize
    optical properties, thermal stability and
    resistance to thermal shock
  • Cermets
  • Combinations of metals and ceramics(oxides,
    nitrides, or carbides) bonded together in the
    same way powdered metallurgy parts are made.
  • Examples crucibles, jet engine nozzles

17
Composites
  • Laminar or Layer Composites - alternate layers of
    materials bonded together. (e.g. plywood, safety
    glass, Formica, bimetallic strips)
  • Particulate Composites - discrete particles of
    one material surrounded by a matrix of another
    material. (e.g. concrete, asphalt, powdered
    metals and ceramics)
  • Fiber-Reinforced Composites - composed of
    continuous or discontinuous fibers embedded in a
    matrix of another material. (e.g. Kevlar, rayon,
    steel reinforced tires, fiberglass,
    graphite-epoxy)

18
Review
Major Categories of Materials
  • Organics
  • Metals and Alloys
  • Polymers
  • Ceramics
  • Composites
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