|
BORON
(B)
MATERIAL
OVERVIEW
Characteristics:
Nonmetallic element, black, hard solid; brown,
amorphous powder; crystals.
Highly reactive. Soluble in concentrated nitric
acid and sulfuric acid; insoluble in water, alcohol,
and ether. High neutron absorption capacity. Low
toxicity. Amphoteric. A plantmicronutrient. Mohs
hardness 9.3.
Derivation:
(a) by heating boric oxide with powdered magnesium or
aluminum; (b) by vaporphase reduction of boron
trichloride hydrogen over hot filaments (800-2000 oC);
(c) electrolysis of fused salts.
Hazard:
Dust ignites spontaneously in air; severe fire and
explosion hazard. Reacts exothermally
with
metals over 900 oC;
explodes with hydrogen iodide.
GENERAL
PROPERTIES
|
Symbol:
|
B
|
|
Atomic
Number:
|
5
|
|
Atomic
Weight:
|
10.81
|
|
Density:
|
2.34
cryst. gm/cc
|
|
Melting
Point:
|
2079
oC
|
|
Boiling
Point:
|
2550
oC
|
|
Thermal
Conductivity:
|
0.274
W/cm/oK
@ 298.2 oK
|
|
Electrical
Resistivity:
|
1.8
x 1012
microhm-cm
@ 0 oC
|
|
Electronegativity:
|
2.0
Paulings
|
|
Specific
Heat:
|
0.245
Cal/g/oK
@ 25 oC
|
|
Heat
of Vaporization:
|
128
K-Cal/gm atom at 2550 oC
|
|
Heat
of Fusion:
|
5.3
Cal/gm mole
|
|
Heat
of Sublimation:
|
133
+ 4 K-Cal/mole @ 0 oK
|
|
Vapor
Pressure:
|
4.6
x 10-4
to
8.5 x 10-3
mm
@2200 oK
|
|
Heat
of Combustion with O2:
|
150.49
K-Cal/mole @ 25 oC
149.79
K-Cal/mole @ 450 oC
|
|
Crystal
Structure:
|
a-rhomohedral,
b-rhombohedral and possible other forms
|
|
Energy
Gap:
|
About
1.4 ev. @ 0 oK
|
|
Hardness,
Knoop:
|
100
gm load: 2500
|
|
Hardness,
Mohs:
|
Approx.
9.3
|
|
Coefficient
of expansion mean:
|
20-750
oC:
8.3 x 10-6
oC
|
|
Specific
Magnetic Susceptibility:
|
-0.62
x 10-6
cgs
@ 2000 oC
(Diamagnetic)
|
|
Ductility:
|
Brittle
|
|
Bending
Strength:
|
76,000
psi
|
|
Heat
Content (Enthalpy):
|
290.4
Cal/mole @ 298.16 oK
22,630
Cal/mole @ 3000 oK
|
|
Entropy:
|
1.4
Cal/deg/mole @ 298.16 oK;
16.5 @ 3000 oK
|
|
Heat
Capacity:
|
2.65
Cal/deg/mole @ 298.16 oK;
7.1 @ 1200 oK
|
TYPICAL
ANALYSES
Impurities
in ppm
|
Material
/ Purity:
|
2N5
|
2N8
|
5N5
|
6N
|
|
Fe
|
<2000
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<500
|
-
|
-
|
|
Mg
|
<100
|
<100
|
1.0
|
-
|
|
Si
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<2000
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<500
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<4
|
<2
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BORON
POWDER, SHOT, PELLETS, & INGOT
|
Material
|
Purity
|
|
Boron
Rod 3-5mm, Irregular Diameter 
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6N
|
|
Boron
Powder amorphous
|
1N2
|
|
Boron
Powder crystalline, 1mm & down 2N5
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3N,
4N, 5N
|
|
Boron
Powder crystalline, -60 Mesh
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2N7
|
|
Boron
Powder crystalline
|
5N5
|
|
Boron
Powder amorphous
|
1N2
|
Rod
is cut to order and sold by the gram.
BORON
COMPOUNDS
|
Material
|
Purity
|
|
Boron
Carbide, B4C,
-60 Mesh
|
2N5
|
|
Boron
Carbide, B4C,
-325 Mesh
|
2N5
|
|
Boron
Carbide, B4C,
5 Microns or lower
|
2N5
|
|
Boron
Iodide, BI3,
Crystals
|
3N
|
|
Boron
Nitride, BN, 1 Micron or lower
|
2N5
|
|
Boron
Nitride, BN, -80 Mesh
|
1N75
|
|
Boron
Nitride, BN Sheet & Rod .250” to 1.0”
2N5
|
2N5
|
|
Boron
Oxide, B2O3,
1/2" Pieces by Down
|
5N5
|
|
Boron
Oxide, B2O3,
-200 Mesh
|
1N8
|
|
Boron
Silicide, B4Si,
-200 Mesh
|
1N8
|
|
Boron
Silicide, B6Si,
-200 Mesh
|
1N8
|
Compounds
are packaged to order and sold by the gram or
kilogram.
|
 |
