Physical Properties of metals

• State 


  Metals are solid at room temperature (Except Hg and Ga)
• Luster


  Metals can reflect light from its surface and can be polished
• Malleability


  Metals can be hammered into thin sheets (Except Zn, As, Hg)
• Ductility


  Metals can be drawn into wires (Except Hg and Zn)
• Conduction


  Metals can conduct heat and electricity. (Except Hg and Pb)
• High Tensile Strength 


  Metals can hold heavy weights. (Except Na, Hg, Zn)
• Sonorous


  Metals can produce a ringing sound when strike. (Except Hg)
• Hardness


  Metals cannot be cut easily (Except Na and K)
• Density


  Metals are high in density and heavy. (Except Al, Mg, Ti, Be)
• High Melting and Boiling Point


  Metals have specific high melting and boiling point. (Except Na, K, Hg, Ga, and Cs)
• Mechanical properties

  Strength

  Hardness

  Toughness

  Elasticity

  Plasticity

  Brittleness

  Ductility

  Malleability
• Electrical Properties

  Conductivity

  Resistance

  Magnetic
• Compression stress - develop within a material when forces compress or crush the material. supports overhead beam
• Tensile stress - this stress developed when a material is subject to a pulling load. For example, when a wire rope is used to lift a load or when using it as a guy to anchor an

  antenna .
• Shearing stresses

  when external forces are applied along parallel lines in opposite

  directions.
• Fatigue - is the tendency of a material to fail after repeated

  bending at the same point.
• Chemical Properties

  Reaction with water, oxygen, acid, base and displacement reaction.
• Metalloids - have properties between metals and nonmetals. useful in the semiconductor industry.

  •all solid at room temperature.

  •can form alloys with other metals.

  •Some can act as electrical conductors under the right conditions; thus they are called semiconductors (e.g., silicon and germanium)
• Ferrous Metallurgy (Black Metallurgy)

  -involves processes and alloys based on iron

  -95% of world metal production

  -iron class and magnetic in nature

  -metals consists of iron, steel and alloys related to them
• Ferrous metals – only encompasses iron, chromium, manganese and their alloys
• Non-ferrous metallurgy (Colored Metallurgy)

  -involves processes and alloys based on other metals

  -divided into aluminum, magnesium, lead, similar groups.
• Alloying 


  Mixture of two or more elements in solid solution; main element is metal.
• Why we alloy? Pure metals are either soft, brittle of chemically reactive for practical use.
• Iron Alloys


  Steel, stainless steel, cast iron, tool steel, alloy steel)s

  •Make up the largest proportion of production (both quantity and commercial value)

  •Alloyed with carbons (low-, mid-, high-carbon steels)

  •Alloyed with silicon (cast irons)

  •Alloyed with chromium, nickel, molybdenum (stainless steels)
• Conductive Alloys


  •Aluminum, titanium, copper, magnesium alloys

  •Significant in commercial value

  •Al, Ti, Mg = high strength to weight ratios; useful in aerospace and automotive applications

  •Copper alloys –electrical wiring
• Corrosion


  •a natural process that causes the transformation of pure metals into undesirable substances when they react with substances like water or air.

  •the reaction causes damage and disintegration of the metal
• Factors affecting corrosion

  • Exposure of the metals to air containing gases like CO2, SO2, SO3 etc.
  • Exposure of metals to moisture, especially salt water (which increases the rate of corrosion)
  • Presence of impurities like salt (For example, NaCl)
  • Temperature: An increase in temperature increases corrosion
  • Nature of the first layer of oxide formed: Some oxides like Al2O3 form an insoluble protecting layer that can prevent further corrosion. Others, like rust, easily crumble and expose the rest of the metal
  • Presence of acid in the atmosphere: Acids can easily accelerate the process of corrosion
• Corrosion Resistance


  property that enables a material to resist entering into chemical combination with other substance from attacks by atmospheric, chemical, or electrochemical conditions.
• Rusting of iron = ?

  Oxidation
• High CR


  very desirable in all metals exposed to weather elements
• Metals are easily corroded.
• Corrosion-Proof Metals

  Stainless steel

  •Aluminum alloy

  •Copper

  •Bronze

  •Brass

  •Galvanized steel