● Description
Alumina ceramics are presently classified into two types: high-purity alumina and ordinary alumina. High-purity alumina ceramics are technical ceramic materials having an Al2O3 composition higher than 99.9%. Ordinary alumina ceramics are classified as 99% Alumina, 95% Alumina, 90% Alumina, 85% Alumina, and other variations based on the amount of Al2O3. Sometimes, those containing 80% or 75% Al203 are also categorised as ordinary alumina ceramic series.
● High Purity Alumina Ceramics
Because of their high sintering temperatures of 1,650-1,990°C and transmission wavelengths of 1-6 um, high-purity alumina ceramics are often produced to replace molybdenum crucibles. Because of its light transmittance and resistance to alkali metal corrosion, it can be used as a sodium lamp. Furthermore, I t is also a suitable substrate choice for integrated circuits and a high-frequency insulating material in the electronics sector.
● The Ordinary Alumina Ceramics
99 alumina ceramic materials are used to manufacture high-temperature crucibles, refractory furnace tubes, and specific wear-resistant materials such as ceramic bearings, ceramic seals, and water valve discs in the ordinary alumina ceramic series. 95 alumina is mainly used as corrosion-resistant and wear-resistant parts. 85 porcelain is frequently mixed with talc, which improves electrical properties and mechanical strength, and can be sealed with molybdenum, niobium, tantalum, and other metals; and some are used as electric vacuum devices.
● What UNIPRETEC Makes
UNIPRETEC specializes particularly in the high series products in ordinary alumina ceramics. Our company's common alumina ceramic materials consist of 95 percent alumina, 96 percent alumina, 99 percent alumina, 99.5 percent alumina, and 99.8 percent alumina. The following are the basic performance parameters of our two main alumina materials.
ITEM | UNIT | ALUMINA | A950 | ALUMINA | A990 |
Main Content | - | 95% Al2O3 | 99% Al2O3 |
Color | - | White | Ivory |
Density | g/cm3 | 3.70 | 3.85 |
Vickers Hardness | Gpa | 14 | 17 |
Flexural Strength | Mpa | 310 | 360 |
Compressive Strength | Mpa | 2,200 | 2,500 |
Volume Resistivity | Ω·cm | >1014 | >1014 |
Dielectric Strength | KV/mm | 15 | 17 |
Dielectric Constant | 1 MHz | 8 | 9 |
Heat Conductivity | W/m.K | 25 | 29 |
Maximum Operating Temp. | ℃ | 1,500 | 1,650 |
Thermal Shock Resistance | △T(℃) | 210 | 230 |
Coefficient of Thermal Expansion (25 - 1,000 ℃) | 10-6/K | 7 - 9 | 7 - 9 |
∆ The above data is offered for reference and comparison only, exact data will vary depending on manufacturing method and part configuration.
