Alumina, Zirconia advanced technical ceramic materials and components
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Oxides - Alumina Oxide, Zirconia/Zirconium Oxide
Alumina, Zirconia
Alumina and zirconia are hard wearing materials used for many applications. Once fired and sintered, they can only be machined using diamond-grinding methods.Alumina's combination of hardness, high temperature operation and good electrical insulation makes it useful for a wide range of applications. Alumina is the most commonly used type of ceramic and is available in purities up to 99.9%.
Zirconia is similar to alumina in many of its properties but offers significant improvement in fracture toughness. It is particularly useful in applications where the mechanical strength of alumina is not sufficient.
Typical applications: electrical insulators; seal faces; valve seats.
Oxides Physical Properties
| name | Alumina 96% Substitute | High-Purity crystalised Alumina | High-Purity Alumina | Quartz | Sapphire | BeO | Zirconia Yttizia Stabalised | Zirconia Mgo Stabalised | Steel(mild) |
| colour | white | off-white | off-white | clear | clear | white | white | cream | grey |
| density | 3.8g/cm | 3.8g/cm | 3.5g/cm | 2.2g/cm | 4g/cm | 2.9g/cm | 8g/cm | 5.6g/cm | 7.85kg dm |
| porosity | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | |
| poissons ratio
| 0.3 | 0.31 | 0.27-0.30 | ||||||
| thermal conductivity
| 24 Wm/K | 30 Wm/K | 28-28 Wm/K | 1.48 Wm/K | 35-40 Wm/K | 260 Wm/°C | 2 Wm/K | 2.5 Wm/K | 50 Wm/°C |
| coeffcient of expansion
| 8 x 10-6/K | 10 x 10-6/°C | 11x10/°C | ||||||
| dielectric strength
| 10 KV/mm | 17 KV/mm | 10 25KV/mm | 25 40KV/mm | 15 50KV/mm | 10 KV/mm | |||
| dielectric constant
| 9.8 | 9.9 | 9-10 | 3.8 | 7.5- 11.5 | 7 1MHZ | |||
| dielectric loss tangent
| 0.0003 1MHZ | ||||||||
| flexual strength
| 200 MPa | 800- 1400 MPa | 545 MPa | ||||||
| hardness | 1500 Vickers | 9 Mohs Scale | 1650 Vickers | 1000 Vickers | 1700 Vickers | 1200 Vickers | 1350 Vickers | 910 Vickers | |
| volume resistancy
| >1013 ohm/cm | >1014 ohm/cm | 1014 ohm/cm | 1018 ohm/cm | 1014 ohm/cm | >1014 ohm/cm | >109 ohm/cm | >1010 ohm/cm | |
| max. use temp
| 1600°C | 1900°C | 1650°C | 1100-1400°C | 2000°C | 1700°C | 1000°C | 1000°C | |
| thermal expansivity
| 8.5x 10-16 | 7.5- 8.2 10-6 | 54 10-6 | 5.8 10-6 | 10x10°C | 11x10/°C | |||
| specific heat
| 800 J/KgK | 900 J/KgK | 880 J/KgK | 700 J/KgK | 750 J/KgK | 1000- 1320 J/KgK | 400 J/KgK | 400 J/KgK | 450J/kgK |
| compressive strength
| 3500 MPa | 2000- 2250 GPh | 1100 | 2100 | 1750 MPa | 2000 MPa | 1700 MPa |