Materials & Components by YEhmBCM


									Materials & Components

      Metals & Alloys
          Basic Classification


                          ALLOYS:          NON-FERROUS:
Contain iron. Almost
                       Mixture of two or   Pure metals, don’t
all are magnetic and
                         more metals          contain iron
  corrode quickly if
      Ferrous: Production of Steel
•   Ore is mined
     – Magnetic ores (upto 65% iron – Sweden, USA, USSR)
     – Haematite ores (40-60% iron – Spain & USA, Some
       GB deposites)
•   Initial treatment
     – Washed
     – Graded (roasted to remove some of carbon, water &
     – Crushed (to usable lumps – 100mm cubes)
•   Refined
     – Iron ore, coke & limestone placed in blast furnace
     – Heated air blasted into furnace causes coke to burn
     – Limestone decomposes and separates impurities
     – Impure ‘slag’ forms at top and tapped off – ballast and
       road building
     – Heavier pig-iron forms at bottom
   Basic Oxygen Furnace for the
        Production of Steel
• Because pig iron is hard but quite brittle,
  it is not very useful in this state.
• To produce steel, most of the impurities
  are removed by blowing hot oxygen
  through the molten pig iron for a short
  time in a basic oxygen furnace. This
  process oxidizes the impurities which
  escape as gases or form slag.
• A typical basic oxygen furnace is
  charged with about 200 tons of molten
  pig iron,100 tons of scrap iron, and 20
  tons of limestone.
• The product of the basic oxygen furnace
  is carbon steel, which is strong and
  malleable and therefore much more
  useful than pig iron.
                       Iron & Steel
Steel is a combination of iron and carbon    Hard &
• Cast Iron (3% – 4%)

• High Carbon Steel (0.7% - 1.4%)

• Medium Carbon steel (0.3% - 0.7%)

• Mild Steel (0.15% - 0.3%)

• Low Carbon Steel (less than 0.15%)
                                             Soft &
         Non-Ferrous Metals
• Aluminium

• Copper

• Zinc
            Production of Aluminium
Mined as Bauxite
(USA, France, Guayana, Australia, Africa)

1.     Treated with caustic soda
       and heated under pressure
2.     Filtered and washed
3.     Heated to 1100 C in rotary
       kiln to form Alumina
       (Aluminium Oxide)
4.     Reduced by electrolysis to
       separate oxygen and
5.     Heavier aluminium sinks and
       is siphoned off and cast into
            Production of Copper
• Relatively scarce (USA, Chile, Canada,
  Zambia USSR – historically: Wales)
• Ore contains less than 4% copper
• Ore crushed
• Separated from rock by floatation
  (grains of copper float, rock sinks)
• Smelted in a reverbatory furnace, lime
  added as flux. Impurities tapped off.
• Either:
   – Remelted, impurities oxidised and
     removed as slag, followed by ‘poling’ –
     oxygen removed by combustion
   – Electrolytic refining in sulphuric acid,
     copper deposited on cathode
         Production of Zinc
• Ore Zinc Blonde
• Crushed and concentrated by floatation
• Smelted in blast furnace
• Zinc removed as vapour and condensed in
  contact with molten lead
• Electrolysis produces very pure form.
            Common Alloys
• Stainless steel
 (Medium carbon steel + 12% chromium + 8% nickel)

• Aluminium Alloys
 Duralumin (Aluminium + 4% copper + 1% magnesium)

• Brass
 (65% copper, 35% zinc)

 Close Packed         Face Centred            Body Centred
Hexagonal (CPH)        Cube (FCC)              Cube (BCC)
Weak, poor strength    Very ductile,           Hard, tough
  to weight ratio     good electrical

  Iron (below 910C    Iron (910-1400C),    Chromium, tungsten
  and above 1400C),   aluminium, copper,
  zinc, magnesium     gold, silver, lead
• Pure metals solidify at a
  fixed temp
• Crystals form in either
  cube or fixed structure
• Further cooling causes
  crystals to grow
  (dendrites) until one
  touches its neighbour
• Where dendrites meet,
  boundaries are formed to
  produce grains
          Steels worksheet
• Using the table 3.1.1

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