Standard Alumina (74%, 95%, 96%, 98%)

Aluminum Oxide, or alumina, is the most common technical ceramic material used today. The versatility of alumina stems from its broadly impressive material properties, ease of manufacture, wide availability, and budget-friendly cost. STC produces a range of alumina purity from 74% alumina to 99.96% alumina - these bodies are the industry work-horse materials for applications that require electrical isolation, wear resistance, high temperature resistance, and good mechanical strength.

Alumina sees application from aerospace to medical, from bearings to analytical instrumentation, from electrical standoffs to semiconductor processing. In addition, these materials lend themselves well to be hermetically sealed to metals through metallizing and brazing methods.

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Prime Features
Performs well in corrosive environments 
Typical Applications
Structural ceramic partsAerospace
Analytical instrumentation 

Materials Property Chart
 PropertyASTM MethodUnitsAL74 74%AL95 95%AL96 96%AL98 98%
GeneralCrystal Size (Average)Thin SectionMicrons131187
Color----WhiteIvoryWhite Or PurpleWhite
Gas Permeability--atms-cc/secgas tight <10-10gas tight <10-10gas tight <10-10gas tight <10-10
Water AbsorptionC 20-97%0000
MechanicalDensityC 20-97g/cc3.033.653.713.78
HardnessVickers 500gmGPa (kg/mm2)10.5 (1075)11.5 (1175)12.7 (1300)12.7 (1300)
Fracture ToughnessNotched BeamMPam1/22 - 53 - 44 - 54 - 5
Flexural Strength (MOR)
(3 point) @ RT
F417-87MPa (psi x 103241 (35)310 (45)358 (52)393 (57)
Tensile Strength @ RT--MPa (psi x 103)117 (17)151 (22)200 (29)221 (32)
Compressive Strength @ RT--MPa (psi x 103)1378 (200)1827 (265)2068 (300)2241 (325)
Elastic ModulusC848GPa (psi x 106)172 (25)303 (44)310 (45)345 (50)
Poisson's RatioC848--
ThermalC.T.E. 25 - 100° CC 372-96x 10-6/C5.
C.T.E. 25 - 300° CC 372-96x 10-6/C5.
C.T.E. 25 - 600° CC 372-96x 10-6/C6.
Thermal Conductivity @ RTC 408W/m K4192329
Max Use Temp--Fahrenheit (°F)2800300031003100
--Celsius (°C)1540165017001700
ElectricalDielectric Strength (.125" Thick)D 149-97AV/mil225250250260
Dielectric Constant @ 1 MHzD 150-98--
Dielectric ConstantD 2520-95----
@ GigahertzD 2520-95----
Dielectric Loss @ 1 MHzD 150-98--0.00120.00060.00040.0006
Dielectric LossD 2520-95----0.00090.00070.0005
@ GigahertzD 2520-95----12.510.99.8
Volume Resistivity, 25°CD 257ohms-cm< 1 x 1013> 1 x 1014> 1 x 1014> 1 x 1014
Volume Resistivity, 300°CD 1829ohms-cm4 x 10105 x 10123 x 10128 x 1011
Volume Resistivity, 500°CD 1829ohms-cm3 x 1073 x 1097 x 1092 x 109
Volume Resistivity, 700°CD 1829ohms-cm2 x 1063 x 1084 x 1082 x 108
Note: The information in this data sheet is for design guidance only. STC does not warrant this data as absolute values. Forming methods and specific geometry could affect properties. Slight adjustments can be made to some of the properties to accommodate specific customer requirements. Most of the dense materials in the table are resistant to mechanical erosion and chemical attack. STC has performed ASTM testing qualification for certain compositions, in accordance with ASTM D2442. Please consult our technical staff for appropriate material and specific test results.