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ALUMINUM
COMPOUNDS (Al)
MATERIAL
OVERVIEW
Characteristics:
Pure aluminum is a silvery white, crystalline solid. Tensile strength
(annealed) 6800 psi, coldrolled 16,000 psi. Forms
protective coating of Al2O3
about
50 thick, which makes it highly resistant to
ordinary corrosion. Attacked by concentrated and
dilute solutions of HCl, hot conc.
H2SO4
and
perchloric acid, also violently by strong alkalies.
Rapidly oxidized by water at 180 oC. Not attacked by dilute or cold concentrated H2SO4
and
concentrated nitric acid. Electrical conductivity
about 2/3 that of copper. Aluminum qualifies as both a
light metal and a heavy metal, according to their
respective definitions.
It is most widely used for kitchen utensils,
outside decoration, and in thousands of industrial
applications where a strong, light, easily constructed
material is needed.
Although its electrical conductivity is only about
60% that of copper, it is used in electrical
transmission lines because of its light weight. Pure
aluminum is soft and lacks strength, but alloyed with
small amounts of copper, magnesium, silicon,
manganese, or other elements impart a variety of
useful properties.
These alloys are of vital importance in the
construction of modern aircraft and rockets. Aluminum,
evaporated in a vacuum, forms a highly reflective
coating for both visible light and radiant heat. These
coatings soon form a thin layer of the protective
oxide and do not deteriorate as do silver coatings.
They are used to coat telescope mirrors and to make
decorative paper, packages, and toys.
Derivation:
From bauxite by Bayer process (q.v.) and subsequent
electrolytic reduction by Hall process (q.v.). There
are several processes for obtaining ultrapure
aluminum: (a) electrolytic (three-layer); (b) zone
refining (q.v.); and (c) chemical refining. Purities
up to 6N8 are possible.
More efficient processes are the Alcoa and Toth
processes (q.v.); these require much less electric
power than the Hall process (q.v.); Another method,
using no electricity, involves heating a mixture of
aluminum ores with a coal-derived fuel in a closed
furnace; this yields AlOSi alloys, which are not only
useful as such, but can be refined to pure aluminum.
Hazard:
Fine powder forms flammable and explosive mixtures in
air. Tolerance, 10 mg/m3
of
air; soluble salts, 2 mg/m3 of air. Nontoxic and
noncombustible except in powder forms.
GENERAL
PROPERTIES
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Symbol:
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Al
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Atomic
Number:
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13
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Atomic
Weight:
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26.98154
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Density:
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2.6989
gm/cc
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Melting
Point:
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660.37
oC
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Boiling
Point:
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2467
oC
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Thermal
Conductivity:
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2.37
W/cm/oK @ 298.2 oK
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Electrical
Resistivity:
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2.6548
microhm-cm @ 20 oC
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Electronegativity:
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1.5
Paulings
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Specific
Heat:
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0.215
Cal/g/oK @ 25 oC
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Heat
of Vaporization:
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67.9
K-cal/gm atom at 2467 oC
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Heat
of Fusion:
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2.55
Cal/gm mole
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TYPICAL
ANALYSES
Impurities
in ppm
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Material
/ Purity:
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4N
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5N
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6N
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Ca
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<65
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1.0
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0.1
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Cu
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<10
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1.0
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0.2
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Mg
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2
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2.0
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0.2
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Mn
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1
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2.0
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0.2
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Si
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10
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1.0
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-
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Fe
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<10
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2.2
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-
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ALUMINUM
COMPOUNDS
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Material
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Purity
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Aluminum
Antimonide, AlSb, 1/4" Pieces by Down
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5N
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Aluminum
Arsenate, AlAsO4*8H2O,
-80 Mesh
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2N
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Aluminum
Arsenide, AlAs, -20 Mesh
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2N8,
3N, 5N
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Aluminum
Bromide, AlBr3, -10 Mesh
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2N5,
5N
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Aluminum
Carbide, Al4C3,
-325 Mesh
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2N,
4N
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|
Aluminum
Chloride, AlCl3, -10 Mesh
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3N,
5N
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Aluminum
Fluoride, AlF3, 1/2"-1/8"
Pieces
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2N5
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Aluminum
Fluoride, AlF3, -100 Mesh
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2N5
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Aluminum
Iodide, AlI3, -10 Mesh
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5N
3N
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Aluminum
Molybdate, Al2(MoO4)3,
-100 Mesh
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2N5
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Aluminum
Oxide, Al2O3,
-40 Mesh
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4N
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Aluminum
Oxide, Al2O3,
1/2"-1/8" Pieces
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2N8,
4N
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Aluminum
Oxide, Al2O3,
-100, +325 Mesh
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2N6
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Aluminum
Oxide, Al2O3,
-150, +325 Mesh
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2N6
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Aluminum
Oxide, Al2O3,
-325 Mesh
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2N6
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Aluminum
Selenide, Al2Se3, 1/4"
Pieces by Down
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3N
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Aluminum
Sulfide, Al2S3, 1/4"
Pieces by Down
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Aluminum
Sulfide, Al2S3, -100 Mesh
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3N,
4N
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Aluminum
Tellurate, Al2(TeO4)3, -80 Mesh
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Aluminum
Telluride, Al2Te3, 1/4"
Pieces by Down
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Aluminum
Tellurite, Al2(TeO3)3, -80 Mesh
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Aluminum
Tungstate, Al2(WO4)3,
-100 Mesh
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Aluminum
Zirconate,Al2O3+3ZrO2, -100 Mesh
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Compounds
are packaged to order and sold by the gram or
kilogram.
For aluminum single crystals see “Single Crystals.”
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