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Aluminum Oxide Alumina Ceramic
Aluminum Oxide (Al2O3) is commonly known as alumina. It is a wear-resistant technical ceramic that exhibits an outstanding combination of mechanical and electrical characteristics. It is suitable for a wide variety of industrial applications.
Alumina ceramic has characteristics of high hardness, wear resistance, low erosion levels, high-temperature resistance, corrosion resistance, and bio-inertness. It is especially well suited for high temperature applications. Unipretec Ceramic provides an extensive selection of advanced ceramic products. Advantages of alumina ceramics are as below:
● Excellent electrical insulation
● High hardness and mechanical strength
● Wear and abrasion resistance
● High thermal conductivity and thermal shock resistance
● Low density
● Resistant to strong acid and alkali attack at high temperatures
● Transparent to microwave radio frequencies
● High compressive and dielectric strength
● High thermal conductivity and low thermal expansion
Alumina Material Grades
Unipretec Ceramic offers three types of Alumina: 95 alumina, 99 alumina, and 99.7 alumina. The varying methods employed to manufacture these materials resulted in slightly different characteristics and features.
99 Alumina Ceramic
It’s one of the high performance grades in this material category. It features a 99% purity alumina raw material, providing an excellent combination of mechanical and electrical properties while maintaining a reasonable cost. It is an extremely wear-resistant technical ceramic that is well-suited to various industrial applications where the material must function under demanding conditions.
Furthermore, 99 alumina can be machined in the "green state"--that is, before sintering--to ensure various shapes and sizes.
99.7 Alumina Ceramic
It is a very high purity (99.7%) grade of Alumina (Aluminum Oxide) with remarkable mechanical and electrical properties. In addition to corrosion resistance and chemical inertness, it has very high hardness, great electrical resistivity, mechanical stability at high temperatures, and high strength.
95 Alumina Ceramic
It is a normal purity grade and is one of the mainstays of the technical ceramics sector. It has a 95% purity Alumina raw material, which provides a balanced "cost to quality" ratio. This durable technical ceramic provides an exceptional combination of mechanical and electrical characteristics, making it the perfect choice for various industrial uses where cost is critical but the material must still perform well in mechanical and electrical properties.
Alumina Ceramic Properties
| Item | Unit | Alumina丨A950 | Alumina 丨A990 | Alumina 丨A997 |
| Main Content | - | 95% Al₂O₃ | 99% Al₂O₃ | 99.7% Al₂O₃ |
| Colour | - | White | Ivory | Ivory |
| Density | g/cm³ | 3.65 | 3.85 | 3.90 |
| Water Absorption | ％ | 0 | 0 | 0 |
| Vickers Hardness | Gpa | 14 | 17 | 17.5 |
| Flexural Strength | Mpa | 310 | 360 | 370 |
| Compression Strength | Mpa | 2,200 | 2,500 | 2,600 |
| Electrical Resistivity | Ω · cm | ≥1014 | ≥1014 | ≥1014 |
| Dielectric Strength | KV/mm | 15 | 17 | 17.5 |
| Dielectric Constant | 1MHz | 8 | 9 | 9.5 |
| Thermal Conductivity @20℃ | W/(m · K） | 25 | 29 | 30 |
| Max. Working Temperature | ℃ | 1,500 | 1,650 | 1,700 |
| Resistance to Thermal Shock | ΔT/(℃) | 210 | 230 | 235 |
| CTE (25-1,000℃) | 10-6/K | 7-9 | 7-9 | 7-9 |
Applications of Alumina Ceramic
Alumina is a very hard ceramic that can withstand abrasion and is suitable for wear-resistant inserts or products. It is frequently employed as an electrical insulator at high temperatures, with the higher purity grades providing superior resistivity. Furthermore, it exhibits excellent resistance to strong acids and alkalis, making it an ideal material for applications requiring resistance to corrosive substances. Some common applications include:
● Electronic components & substrates
● High-temperature electrical insulators
● High voltage insulators
● Vacuum Furnace components
● Setters for MIM sintering
● Machine components
● Mechanical seals
● Precision shafts and axles in high wear environments
● Roller and ball bearings
● Seal rings
● Semiconductor parts
● Pump tubes
● Thermocouple protection tubes
● Valve seats
● Wear components
Alumina Machining
Alumina can be made in different purity levels, with additives designed to enhance its properties. Although Unipretec Ceramic usually offers 95%, 99%, and 99.7% alumina material, typical purities range from 90% to 99.9%.
It can be made through extrusion, injection molding, die pressing, isostatic pressing, and slip casting. It can only be machined using diamond grinding techniques after it has been sintered. Unipretec's advanced green and biscuit machining techniques make it possible to fabricate more complex components using traditional machining methods. Furthermore, metals or other ceramics can be easily joined with alumina after brazing and metalizing processes.
Alumina ceramic has three states: green, biscuit, and fully dense. When it is in the green or biscuit state, it's relatively easy to make into intricate geometries. However, the alumina body shrinks by around 20% as a result of the sintering procedure, which is necessary for fully densify the material. Because of this shrinkage, very tight tolerances cannot be maintained when conducting alumina pre-sintering. Diamond tools must be used to mill or grind the fully sintered material in order to attain extremely tight tolerances. During this process, material is ground to achieve the desired shape using a very precise diamond-coated tool or wheel. As a result of the material's inherent durability and hardness, this procedure can be both laborious and expensive.
Unipretec Ceramic specializes in tight tolerance and highly complex work. Our in-house machining facilities include sawing, tapping, threading, drilling, grinding, milling and polishing. Thus, we can provide alumina components that meet strict mesurment requirements.
We are always happy to offer guidance on materials, design, and application based on our many years of experience. We would be pleased to help you if you would like to purchase alumina plates, rods, tubes, or custom machined components. Welcome to contact us and one of our experts will help you.
Typical Products
contact information
If you have any questions about products or services, please contact us immediately and we will reply to you within the first time
No.153, Yuehua Road, Huli District, Xiamen, China
86 18650119402
info@unipretec.com
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