High Purity Alumina (99.5%, 99.8%, 99.96%)

Alumina (Al2 O3) is a common workhorse material in the world of technical ceramics and is utilized in an extensive variety of industries and applications. Alumina’s material properties offer electrical isolation, wear resistance, high temperature resistance, and good mechanical strength. STC’s fully dense, 99.5%, 99.8% and 99.96% alumina bodies offer improved performance over lower purity alumina ceramics in demanding operating conditions.

Our High purity aluminas make for improved corrosion resistance due to lower impurity/silica content. Higher hardness, increased dielectric strength, and in some cases, superior flexural strength. Finer grain sizes also allow for smooth surface finishes. The grade of alumina is selected to best fit the application.

Of our high purity aluminas our 99.96% material exhibits superior flexural strength and dielectric strengths making them excellent candidates for thin walled parts in high-voltage applications.

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Prime Features
High Mechanical StrengthHigh Temperature Resistance
High Wear ResistanceExcellent Corrosion Resistance
Excellent Dielectric StrengthSuitable For food applications
low dielectric lossbio-inert
Typical Applications
High Strength, Thin Walled ComponentsMass Spec Components
End EffectorsPrecision Valve Seats And Seals
bio compatible partspump pistons and sleeves
high voltage dielectric partsfood compatible parts
semiconductor components 

Materials Property Chart
 High Purity Alumina
 PropertyASTM MethodUnitsAL995 99.5%AL9980 99.8%AL9996 99.96%
ElectricalDielectric Strength (.125" Thick)D 149-97AV/mil270290422
Dielectric Constant @ 1 MHzD 150-98--
Dielectric ConstantD 2520-95--9.710--
@ GigahertzD 2520-95--9.89.6--
Dielectric Loss @ 1 MHzD 150-98--0.0002< .0001< .0001
Dielectric LossD 2520-95--< .0001< .0001--
@ GigahertzD 2520-95--9.89.6--
Volume Resistivity, 25°CD 257ohms-cm> 1 x 1014> 1 x 1014> 1 x 1014
Volume Resistivity, 300°CD 1829ohms-cm1 x 10123 x 10121 x 1013
Volume Resistivity, 500°CD 1829ohms-cm5 x 10106 x 10105 x 1012
Volume Resistivity, 700°CD 1829ohms-cm2 x 1096 x 1091 x 1012
ThermalC.T.E. 25 - 100° CC 372-96x 10-6/C6.36.56.5
C.T.E. 25 - 300° CC 372-96x 10-6/C6.97.97.9
C.T.E. 25 - 600° CC 372-96x 10-6/C7.68.18.2
Thermal Conductivity @ RTC 408W/m K303035
Max Use Temp--Fahrenheit (°F)304730473100
--Celsius (°C)167516751700
MechanicalDensityC 20-97g/cc3.883.913.93
HardnessVickers 500gmGPa (kg/mm2)14.3 (1459)15 (1530)19.6 (2000)
Fracture ToughnessNotched BeamMPam1/24 - 53 - 45 - 6
Flexural Strength (MOR)
(3 point) @ RT
F417-87MPa (psi x 103338 (49)379 (55)455 (66)
Tensile Strength @ RT--MPa (psi x 103)172 (25)200 (29)275 (40)
Compressive Strength @ RT--MPa (psi x 103)2137 (310)2240 (325)2413 (350)
Elastic ModulusC848GPa (psi x 106)379 (55)379 (55)393 (57)
Poisson's RatioC848--
GeneralCrystal Size (Average)Thin SectionMicrons662
Color----Ivory - WhiteIvoryOff White/Blush
Gas Permeability--atms-cc/secgas tight <10-10gas tight <10-10gas tight <10-10
Water AbsorptionC 20-97%000
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.