Materials: Non-Ferrous Metals
Zinc
Zinc is a silvery blue-grey
metal with a relatively low melting point
(419.5°C) and boiling point (907°C).
When unalloyed, its strength and hardness
is greater than that of tin or lead, but
appreciably less than that of aluminium
or copper. The pure metal cannot be used
in stressed applications due to low creep-resistance.
For these reasons most uses of zinc are
after alloying with small amounts of other
metals or as a protective coating for steel.
Uses -
One of the most useful characteristics
of zinc is its resistance to atmospheric
corrosion, and just over half of its use
is for the protection of steelwork.
In addition to its metal
and alloy forms, zinc also extends the life
of other materials such as steel (by hot
dipping or electrogalvanizing), rubber and
plastics (as an aging inhibitor), and wood
(in paints). Zinc is also used to make brass,
bronze, and die-casting alloys in plate,
strip, and coil; foundry alloys; superplastic
zinc; and activators and stabilizers for
plastics.
Mechanical and physical properties -
Tensile strength (cast)
: 28MN/m² (4,000 psi)
- (rolled - with grain)
- (99.95% zinc soft temper) : 126MN/m²
(18,000 psi)
- (98.0% zinc hard temper) : 246MN/m²
(35,000 psi)
Elongation :
- (rolled - with grain)
- (99.95% zinc soft temper) : 65%
- (98.0% zinc hard temper) : 5%
Modulus of elasticity : 7 X 104 MN/m²
(1 X 107 psi)
Brinell hardness, 500 kg load :
- for 30 sec. : 30
Impact resistance :
- (pressed zinc, elongation = 30%) : 6.5-9
J/cm² (26-35 ft-1bs/in²)
Surface tension - liquid (450°C) :
0.755 N/m
Surface tension - liquid (419.5°C)
: 0.782 N/m
Viscosity-liquid (419.5°C) : 0.00385
N/m
Velocity of sound (20°C) : 3.67 km/s
Coefficient of friction :
- (rolled zinc v rolled zinc) : 0.21
Hardness : 2.5 mohs
Zirconium
Relatively few metals besides
zirconium can be used in chemical processes
requiring alternate contact with strong
acids and alkalis. Major uses for zirconium
and its alloys are as a construction material
in the chemical-processing industry.
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