Materials > Ceramic Materials > Aluminum Oxide

Aluminum Oxide

Aluminum Oxide (Alumina) & Alumina Products

Alumina, also commonly referred to as sapphire ceramic material, is one of the most versatile ceramic materials because of its high temperature service limit along with its chemical, electrical and mechanical properties. It is also relatively low cost, is easily formed and finished using a number of fabrication methods including injection molding for low cost, high volume production runs. It is often compounded with silica or trace elements to enhance its properties or fabrication and commonly will range from 92% to 99.8% Al2O3. Higher purity, gel cast material can be found under our REPTON brand.

Alumina machined ceramic components can be formed by single axis pressing, isostatic pressing, injection molding, slip casting, or extrusion. Parts can "green machined" to near net size before firing and then "hard" ground using diamond tooling to tolerances less than 0.0002" (0.005 mm). Special grades of alumina can be metallized and/or brazed to metal parts.

For special grades of isopressed alumina for plain and metallized tubes see our ISO ALUMINA Data Sheet and for very large gel cast shapes and ultra high purity (99.99%) see our REPTON and SEMICONDUCTOR pages.

Alumina Oxide (Alumina) Properties

Properties Condition Units 960P 975P 998P 96S IP-95 IP-99
Mechanical
Al2O3 Minimum - % 96.0 97.6 99.8 96.0 99.5 95.0
Bulk Density 20°C g/cm3 3.67 3.72 3.96 3.77 3.65 3.85
Tensile Strength 20°C MPa 205 205 220 nd 160 240
Flexural (Bending) Strength 20°C MPa 375 375 410 295 300 350
Elastic Modulo 20°C GPa 300 355 375 nd 300 350
Hardness 20°C MPa 10 12 14 nd nd nd
Fracture Toughness 20°C MPa-m1/2 4-5 4-5 4-5 nd nd nd
Porosity 20°C % 0 0 0 0 0 0
Thermal
Max. Working temperature

Coef. Thermal Expansion
- °C 1600 1650 1700 na 1500 1700
25-300°C 10-6 /°C 7.1 7.2 7.8 6.7 7.1 7.8
25-1000°C 10-6 /°C 7.4 7.7 8.1 7.4 8.1 8.0
Thermal Conductivity 20°C W/m°K 24 26 28 28.6 20 25
Electrical
Dielectric Strength 2.5mm tk ac-kv/mm 9.2 9.2 10 30 20 20
Dielectric Constant 1 MHz - 9.0 9.4 9.7 9.8 9.0 9.2
Volume Resistivity 20°C Ohm-cm >1014 >1014 >1014 >1014 >1014 >1015
300°C Ohm-cm 109 109 1010 1012 nd nd
1000°C Ohm-cm 106 106 106 107 nd nd
Loss Tangent 1 MHz - 0.028 0.012 0.009 0.0015 0.0003 0.0002
Dissipation Factor 1 MHz - 0.0003 0.0002 0.0001 - - -
Electrical IP,DP,CIM,SC,EX TC IP
IP= Isopress DP= Dry press SC= Slip cast CIM= Ceramic injection molding TC= Tape cast EX= Extrusion
Chemical names and formulas:
formula  Al2O3
name  aluminum oxide
IUPAC name  oxo-oxoalumanyloxyalumane
alternate names  alumina | keto-ketoalumanyloxy-alumane |
   oxo-oxoalumanyloxy-alumane |
   oxo-oxoalumanyloxyalumane
mass fractions  Al (aluminum) 52.9% | O (oxygen) 47.1%
   
Structure Diagram
structure.gif
Basic Properties
Molecular Weight  101.9613 g/mol
Phase  solid (at STP)
Melting point  2040° C
   
Thermodynamic properties
Specific heat of fusion  1.09 kj/g
   
Chemical identifiers
GAS number  1344-28-1
PubChem CID  14769
   
Toxicity properties
Odor odorless
Short-term exposure limit  20 mg/m3

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