Цзифэн Керамика
Overview of Alumina Ceramic Materials
Alumina ceramic is a ceramic material with α-Al2O3 as the main crystalline phase. It is not only inexpensive and readily available, but also possesses high mechanical properties, high electrical insulation, and low dielectric loss. In practical engineering applications, alumina ceramics generally have an Al2O3 content between 75% и 99.9%. Different Al2O3 content results in different properties and applications.
Advantages of alumina ceramics
Alumina ceramics possess high mechanical strength, high volume resistivity, excellent electrical insulation properties, высокая твердость, износостойкость, and oxidation resistance. They are widely used as structural components and functional ceramic parts, such as wear-resistant and corrosion-resistant components in mechanical and chemical industries; crucibles, protective tubes, and refractory materials; and electronic components such as substrates, изоляторы, radar radomes, and microwave dielectrics. Alumina ceramics are one of the earliest studied, widely applied, and relatively mature advanced ceramics.
Кристаллические формы оксида алюминия
Оксид алюминия (Al₂O₃) известно, что существует более чем в десяти кристаллических структурах, в том числе α, с, б, или, д, я, час, κ-Al₂O₃ и аморфная фаза. Среди них, наиболее распространенными и важными являются α-Al₂O₃, γ-Al₂O₃, и β-Al₂O₃. Эти различные формы оксида алюминия демонстрируют существенные различия в структуре и свойствах., которые определяют соответствующие области применения.
α-Al2O3 has a trigonal crystal system, the most compact structure, low chemical activity, good high-temperature stability, excellent electrical properties, and the best mechanical properties.
β-Al2O3 is a polyaluminate mineral with a very high Al2O3 content. Its chemical composition contains a certain amount of alkaline earth metal oxides and alkali metal oxides, and it can also exhibit ionic conductivity.
γ-Al2O3 has a spinel-type cubic structure. It is unstable at high temperatures and has poor mechanical and electrical properties. Однако, it has a high specific surface area and strong chemical activity, and can be used as an adsorbent material after technical improvements.
глиноземная керамика, with α-Al₂O₃ (corundum phase) as the sole main crystalline phase, possess high hardness, high-temperature stability, and excellent electrical insulation properties, making them the preferred material for wear-resistant, structural, and electronic ceramics.
Properties of Al2O3 Ceramics
Al2O3 ceramics have a wide range of applications. Due to the different Al2O3 content, their properties and uses vary accordingly.
| Al₂O₃ Purity | Material Type | Key Characteristics | Типичные применения |
|---|---|---|---|
| ≥ 99.9% | Ultra High-Purity Alumina | Extremely high electrical insulation, excellent chemical purity, superior thermal stability, low dielectric loss | Semiconductor components, электронные подложки, optical and laser components, high-voltage insulation |
| 99.5% – 99.9% | Высокочистый глинозем | High mechanical strength, excellent wear resistance, good thermal conductivity, high dielectric strength | IC substrates, electronic packages, precision insulators, medical and laboratory components |
| 99% | Engineering Alumina | Balanced mechanical strength and cost efficiency, good wear and corrosion resistance | Mechanical seals, bearings, компоненты клапана, industrial wear parts |
| 96% – 98% | Technical Alumina | High hardness, good electrical insulation, cost-effective, easy to process | Electrical insulators, ceramic tubes, втулки, structural components |
| 92% – 95% | Industrial Alumina | Moderate strength, good thermal shock resistance, economical material choice | Furnace parts, thermal insulation components, огнеупорные опоры |
| ≤ 90% | Low-Purity Alumina | Higher porosity, lower mechanical strength, improved thermal insulation | Kiln furniture, heat shields, filtration supports, non-critical structural parts |
Jifeng Ceramic Materials Performance Table
| Свойство | Единица | А-100 | А-200 | А-300 | AZ-100 |
|---|---|---|---|---|---|
| Материал | – | 97% Al2О3 | 99.5% Al2О3 | 99.7% Al2О3 | ZrO2 / Al2О3 |
| Colour | – | White ivory | Ivory White | Белый | Белый |
| Плотность | г/см³ | 3.75 | 3.9 | 3.92 | 4.2 |
| изгибная прочность | МПа | 280 | 370 | 320 | 480 |
| Прочность на сжатие | МПа | 2250 | 2300 | 2450 | 2700 |
| Modulus of Elasticity (Young’s) | ГПа | 330 | 380 | 370 | 350 |
| Вязкость разрушения | MPa·m1/2 | 3 | 4.5 | 4 | 5.5 |
| Коэффициент Пуассона | – | 0.23 | 0.22 | 0.22 | 0.24 |
| Твердость | HRA | 90 | 91 | 91 | 91 |
| Твердость по Виккерсу | HV1 | 1450 | 1550 | 1600 | 1600 |
| Коэффициент теплового расширения | 10-6/К | 7.1 | 6.8 | 6.8 | 9.2 |
| Теплопроводность | W/mk | 25 | 32 | 32 | 8 |
| Устойчивость к тепловому удару | – | 200 | 220 | 220 | 470 |
| Максимальная температура использования (Окислительный) | °С | 1200 | 1400 | 1650 | 1000 |
| Максимальная температура использования (Inert) | °С | 1200 | 1400 | 1700 | 1000 |
| Объемное сопротивление (20°С) | О·см | 1014 | 1015 | 1015 | 1014 |
| Диэлектрическая прочность | кВ/мм | 16 | 20 | 20 | 16.5 |
| Диэлектрическая проницаемость (1МГц) | – | 11.5 | 11 | 10 | 11 |
| Dielectric Loss Angle (20°С, 1МГц) | tanδ | 3×10-3 | 1×10-3 | 1×10-3 | 2×10-2 (9ГГц) |
Как производят глиноземную керамику?
Based on product performance requirements (such as mechanical strength, изоляция, and thermal conductivity), alumina powder of the appropriate purity and specifications is selected. Through ball milling and mixing, adding trace amounts of performance modifiers, and then spray granulation, free-flowing spherical particles are obtained, preparing them for subsequent molding.
- The forming technique is selected based on the product shape and requirements, including dry pressing, изостатическое прессование, injection molding, and tape casting.
- The core objective is to ensure uniform green body density and prevent cracking or deformation during sintering due to stress concentration.
- This is a crucial step in achieving the final performance of the material. The process involves debinding to remove organic binders, followed by sintering at high temperatures. This process requires precise control of the heating curve, holding time, and cooling rate to densify and bond the powder particles, forming a robust microstructure.
- Advanced techniques such as hot isostatic pressing or spark plasma sintering can further suppress grain growth, resulting in a nearly pore-free, highly dense structure.
- The sintered blanks require high-precision processing through diamond tool grinding, притирка, полировка, and even laser cutting to meet strict dimensional and surface finish requirements.
- The final product undergoes comprehensive testing, including density, porosity, microstructure (SEM), and mechanical properties.
Jifeng Ceramics offers alumina materials with purity ranging from 92% к 99.9%. We utilize various forming methods, including dry pressing, slip casting, изостатическое прессование, injection molding, and gel casting, to meet diverse customer needs and the technical requirements of complex parts.
Jifeng Ceramics possesses atmospheric sintering, hot pressing, and internationally advanced hot isostatic pressing and pressureless sintering furnaces, as well as various precision ceramic processing and testing equipment, to meet the needs of manufacturing complex structures and high-precision parts.
With advanced processing equipment and extensive technical expertise, we can provide customers with a full range of solutions, from material selection and design optimization to customized processing, helping them obtain high-quality alumina ceramic products.
If you need to purchase alumina plates, стержни, tubes, or custom-machined parts, please contact us. Our experts will be happy to assist you.
Часто задаваемые вопросы о глиноземной керамике
Is alumina ceramic brittle?
Alumina ceramic is harder than most metals, but it is also more brittle by nature. This does not mean it is unreliable. In most industrial applications, proper thickness, backing design, and installation greatly reduce the risk of cracking or chipping. For high-impact areas, ceramic-metal composite designs are often used.
What alumina purity should I choose for my application?
The right purity depends on working conditions. 92% alumina is commonly used for general wear protection. 95% к 97% alumina offers a good balance of strength, износостойкость, and cost. 99% alumina is preferred for high-temperature or electrical insulation applications. Selecting the right grade helps avoid overdesign and unnecessary cost.
Can alumina ceramics replace steel or rubber liners?
Alumina ceramics can replace steel or rubber in many wear applications, especially where abrasion is the main failure mode. In systems with extreme impact or vibration, a hybrid solution combining ceramic and metal is often more effective. Material selection should always consider the full operating environment.
Where are alumina wear ceramic liners most commonly used?
Alumina wear ceramic liners are widely used in mining, power plants, bulk material handling, химическая обработка, and cement industries. Typical applications include chutes, бункеры, pipelines, elbows, and areas exposed to continuous abrasive flow.
How long do alumina ceramic components typically last?
Service life depends on material grade, installation quality, and operating conditions. In many abrasive environments, alumina ceramics last three to ten times longer than traditional steel liners. This extended lifespan often reduces maintenance and downtime costs.
Are alumina ceramic parts resistant to corrosion and chemicals?
Alumina ceramics show excellent resistance to most acids, щелочи, and chemical media. This makes them suitable for corrosive environments where metal parts would suffer rapid degradation. Однако, compatibility should still be verified for extreme conditions.
Can alumina ceramic parts be customized?
Да. Alumina ceramic components can be customized in material grade, размер, thickness, форма, and mounting method. Customization ensures the ceramic fits the equipment correctly and performs reliably under real operating conditions.