The Most Well-known Oxide Ceramic Material
Alumina or aluminum oxide (Al2O3) in its various levels of purity is used more often than any other advanced ceramic material. CeramTec offers a wide range of material types with different property profiles that can be adjusted via a targeted matrix design.
Aluminium oxide Related Data
| Main component | 99%Al2O3 | S-SiC | ZrO2 | Si3N4 |
Physical
Property | Density | g/cm3 | 3.9 | 3.1 | 6 | 3.2 |
| Water Absorption | % | 0 | 0.1 | 0 | 0.1 |
| Sinter Temperature | °C | 1700 | 2200 | 1500 | 1800 |
Mechanical
Property | Rockwell Hardness | HV | 1700 | 2200 | 1300 | 1400 |
| Bend Strength | kgf/mm2 | 3500 | 4000 | 9000 | 7000 |
| Compression Intensity | Kgf/mm2 | 30000 | 20000 | 20000 | 23000 |
Thermal
Property | Maximum working
temperature | °C | 1500 | 1600 | 1300 | 1400 |
thermal expansion
coefficient
0-1000°C | /°C | 8.0*10-6 | 4.1*10-6(0-500°C) | 9.5*10-6 | 2.0*10-6(0-500°C) |
| 5.2*10-6(500-1000°C) | 4.0*10-6(500-1000°C) |
| Thermal Shock resistance | T(°C) | 200 | 250 | 300 | 400-500 |
| Thermal Conductivity | W/m.k(25°C | 31 | 100 | 3 | 25 |
| 300°C) | 16 | 100 | 3 | 25 |
Electrical
Property | Resisting rate of Volume | ◎.cm | | | | |
| 20°C | >1012 | 106-108 | >1010 | >1011 |
| 100°C | 1012-1013 | – | – | >1011 |
| 300°C | >1012 | – | – | >1011 |
Insulation Breakdown
Intensity | KV/mm | 18 | semiconductor | 9 | 17.7 |
| Dielectric Constant (1 MHz) | (E) | 10 | – | 29 | 7 |
| Dielectric Dissipation | (tg o) | 0.4*10-3 | – | – | – |
Aluminum oxide (Al2O3) has an exceptional set of properties:
- high hardness;
- good heat conductivity;
- excellent corrosion resistance;
- low density;
- stability in a wide range of temperatures;
- electrical insulation properties;
- low cost relative to other ceramic materials.
All these combinations make the material irreplaceable in the manufacture of corrosion-resistant, wear-resistant, electrical insulating and heat-resistant products for a variety of industries.
There are two main types of aluminum oxide:
- Dense Aluminum Oxide (Al2O3)
- Refractory Alumina (Al2O3)
Dense Aluminum Oxide (Al2O3)
This material is used in production of responsible and mechanically loaded products, i.e. mainly as engineering and structural ceramics. The material has excellent corrosion-resistant, wear-resistant, electrical insulating and heat-resistant properties, in addition to resistance to thermal shock. If a thermal shock is present during operation, it is recommended to use refractory materials.
There are several modifications of dense aluminum oxide depending on the content of the main phase and admixtures, which differ in strength and chemical resistance (ALOX-AP, ALOX-HP).
Basic properties of the material
| Properties | Brand of material |
| ALOX-AP | ALOX-HP |
| | Al2O3
94-96% | Al2O3
99,7% |
| Density, g/sm3 | 3,6-3,7 | 3,8-3,9 |
| Isolated porosity, % | 0 | 0 |
| Hardness, GPa | 12-13 | 15-17 |
| Flexural strength, MPa | 300-330 | 350-400 |
| Compressive strength, MPa | 2000-2200 | 2000-2400 |
| Thermal conductivity at 20-100°С, W/mK | 20-25 | 28-33 |
| Coefficient of linear thermal expansion at 20-1000°С, 10-6К-1 | 7,0-8,0 | 7,0-8,0 |
Maximum operating temperature
Oxidative environment
A reducing or inert environment | 1500
1500 | 1750
1750 |
The main applications are:
- bearings for pumps and compressors;
- rings of mechanical seals;
- ceramic plungers;
- elements of valves and stop valves;
- lining for protection from wear and corrosion;
- grinding bodies;
- lining for cyclones and calciners for cement plants;
- nozzles;
- crucibles, boats;
- covers and tubes of thermocouples, rods;
- burners;
- electro technical ceramics;
- products for the glass industry;
- furniture and lining of furnaces;
- positional and welding pins for the automotive industry;
- products for the paper and printing industry;
- drags, eyes, dies, thread guides;
- substrates, plates;
- products for the metallurgical industry;
- abrasive and building materials, tools, welding ceramics;
- products for chemistry and petro chemistry.
