Aluminum
Oxide, Al2O3 Ceramic Properties
Alumina
is one of the most cost effective and widely used material in the family of
engineering ceramics. The raw materials from which this high
performance technical grade ceramic is made are readily available and
reasonably priced, resulting in good value for the cost in fabricated
alumina shapes. With an excellent combination of properties and an
attractive price, it is no surprise that fine grain technical grade
alumina has a very wide range of applications.
.Key
Properties
|
 |
Hard, wear-resistant |
|
Excellent dielectric properties from DC to GHz
frequencies |
|
Resists strong acid and alkali attack at elevated
temperatures |
|
Good thermal conductivity |
|
Excellent size and shape capability |
|
High strength and stiffness |
|
Available
in purity ranges from 94%, an easily metallizable composition, to 99.8%
for the most demanding high temperature applications. |
.
Typical Uses
|
|
Gas laser tubes |
|
Wear pads |
|
Seal rings |
|
High temperature electrical insulators |
|
High voltage insulators |
|
Furnace liner tubes |
|
Thread and wire guides |
|
Electronic substrates |
|
Ballistic armor |
|
Abrasion resistant tube and elbow liners |
|
Thermometry sensors |
|
Laboratory instrument tubes and sample holders |
|
Instrumentation parts for thermal property test
machines |
|
Grinding media |
General Information
Aluminum
oxide, commonly referred to as alumina, possesses strong ionic
interatomic bonding giving rise to it’s desirable material
characteristics. It can exist in several crystalline phases which all
revert to the most stable hexagonal alpha phase at elevated
temperatures. This is the phase of particular interest for structural
applications and the material available from Accuratus.
Alpha
phase alumina is the strongest and stiffest of the oxide ceramics. Its
high hardness, excellent dielectric properties, refractoriness and good
thermal properties make it the material of choice for a wide range of
applications.
High
purity alumina is usable in both oxidizing and reducing atmospheres to
1925°C. Weight loss in vacuum ranges from 10–7
to 10–6 g/cm2.sec
over a temperature range of 1700° to 2000°C. It resists attack by all
gases except wet fluorine and is resistant to all common reagents
except hydrofluoric acid and phosphoric acid. Elevated temperature
attack occurs in the presence of alkali metal vapors particularly at
lower purity levels.
The
composition of the ceramic body can be changed to enhance particular
desirable material characteristics. An example would be additions of
chrome oxide or manganese oxide to improve hardness and change color.
Other additions can be made to improve the ease and consistency of
metal films fired to the ceramic for subsequent brazed and soldered
assembly.
Engineering
Properties*
|
94%
Aluminum Oxide
|
|
Mechanical
|
Units
of Measure
|
SI/Metric
|
(Imperial)
|
| Density |
gm/cc
(lb/ft3)
|
3.69
|
(230.4)
|
| Porosity |
% (%)
|
0
|
(0)
|
| Color |
—
|
white
|
—
|
| Flexural Strength |
MPa
(lb/in2x103)
|
330
|
(47)
|
| Elastic Modulus |
GPa
(lb/in2x106)
|
300
|
(43.5)
|
| Shear Modulus |
GPa
(lb/in2x106)
|
124
|
(18)
|
| Bulk Modulus |
GPa
(lb/in2x106)
|
165
|
(24)
|
| Poisson’s Ratio |
—
|
0.21
|
(0.21)
|
| Compressive Strength |
MPa
(lb/in2x103)
|
2100
|
(304.5)
|
| Hardness |
Kg/mm2
|
1175
|
—
|
| Fracture Toughness KIC |
MPa•m1/2
|
3.5
|
—
|
Maximum Use Temperature
(no load) |
°C (°F)
|
1700
|
(3090)
|
|
Thermal
|
|
|
|
| Thermal Conductivity |
W/m•°K
(BTU•in/ft2•hr•°F)
|
18
|
(125)
|
| Coefficient of Thermal Expansion |
10–6/°C
(10–6/°F)
|
8.1
|
(4.5)
|
| Specific Heat |
J/Kg•°K
(Btu/lb•°F)
|
880
|
(0.21)
|
|
Electrical
|
|
|
|
| Dielectric Strength |
ac-kv/mm
(volts/mil)
|
16.7
|
(418)
|
| Dielectric Constant |
@ 1 MHz
|
9.1
|
(9.1)
|
| Dissipation Factor |
@ 1 kHz
|
0.0007
|
(0.0007)
|
| Loss Tangent |
@ 1 kHz
|
—
|
—
|
| Volume Resistivity |
ohm•cm
|
>1014
|
—
|
|
96%
Aluminum Oxide
|
|
Mechanical
|
Units
of Measure
|
SI/Metric
|
(Imperial)
|
| Density |
gm/cc
(lb/ft3)
|
3.72
|
(232.2)
|
| Porosity |
% (%)
|
0
|
(0)
|
| Color |
—
|
white
|
—
|
| Flexural Strength |
MPa
(lb/in2x103)
|
345
|
(50)
|
| Elastic Modulus |
GPa
(lb/in2x106)
|
300
|
(43.5)
|
| Shear Modulus |
GPa
(lb/in2x106)
|
124
|
(18)
|
| Bulk Modulus |
GPa
(lb/in2x106)
|
172
|
(25)
|
| Poisson’s Ratio |
—
|
0.21
|
(0.21)
|
| Compressive Strength |
MPa
(lb/in2x103)
|
2100
|
(304.5)
|
| Hardness |
Kg/mm2
|
1100
|
—
|
| Fracture Toughness KIC |
MPa•m1/2
|
3.5
|
—
|
Maximum Use Temperature
(no load) |
°C (°F)
|
1700
|
(3090)
|
|
Thermal
|
|
|
|
| Thermal Conductivity |
W/m•°K
(BTU•in/ft2•hr•°F)
|
25
|
(174)
|
| Coefficient of Thermal Expansion |
10–6/°C
(10–6/°F)
|
8.2
|
(4.6)
|
| Specific Heat |
J/Kg•°K
(Btu/lb•°F)
|
880
|
(0.21)
|
|
Electrical
|
|
|
|
| Dielectric Strength |
ac-kv/mm
(volts/mil)
|
14.6
|
(365)
|
| Dielectric Constant |
@ 1 MHz
|
9.0
|
(9.0)
|
| Dissipation Factor |
@ 1 kHz
|
0.0011
|
(0.0011)
|
| Loss Tangent |
@ 1 kHz
|
—
|
—
|
| Volume Resistivity |
ohm•cm
|
>1014
|
—
|
|
99.5%
Aluminum Oxide
|
|
Mechanical
|
Units
of Measure
|
SI/Metric
|
(Imperial)
|
| Density |
gm/cc
(lb/ft3)
|
3.89
|
(242.8)
|
| Porosity |
% (%)
|
0
|
(0)
|
| Color |
—
|
ivory
|
—
|
| Flexural Strength |
MPa
(lb/in2x103)
|
379
|
(55)
|
| Elastic Modulus |
GPa
(lb/in2x106)
|
375
|
(54.4)
|
| Shear Modulus |
GPa
(lb/in2x106)
|
152
|
(22)
|
| Bulk Modulus |
GPa
(lb/in2x106)
|
228
|
(33)
|
| Poisson’s Ratio |
—
|
0.22
|
(0.22)
|
| Compressive Strength |
MPa
(lb/in2x103)
|
2600
|
(377)
|
| Hardness |
Kg/mm2
|
1440
|
—
|
| Fracture Toughness KIC |
MPa•m1/2
|
4
|
—
|
Maximum Use Temperature
(no load) |
°C (°F)
|
1750
|
(3180)
|
|
Thermal
|
|
|
|
| Thermal Conductivity |
W/m°K
(BTU•in/ft2•hr•°F)
|
35
|
(243)
|
| Coefficient of Thermal Expansion |
10–6/°C
(10–6/°F)
|
8.4
|
(4.7)
|
| Specific Heat |
J/Kg•°K
(Btu/lb•°F)
|
880
|
(0.21)
|
|
Electrical
|
|
|
|
| Dielectric Strength |
ac-kv/mm
(volts/mil)
|
16.9
|
(420)
|
| Dielectric Constant |
@ 1 MHz
|
9.8
|
(9.8)
|
| Dissipation Factor |
@ 1 kHz
|
0.0002
|
(0.0002)
|
| Loss Tangent |
@ 1 kHz
|
—
|
—
|
| Volume Resistivity |
ohm•cm
|
>1014
|
—
|
*All properties are room temperature values except
as noted.
The data presented is typical of commercially available material and is
offered for comparative purposes only. The information is not to be
interpreted as absolute material properties nor does it constitute a
representation or warranty for which we assume legal liability. User
shall determine suitability of the material for the intended use and
assumes all risk and liability whatsoever in connection therewith.
See also: Ceramic
Rod & Tube
See also: Ceramic Rod &
Tube > Available Aluminum Oxide Sizes
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|
