Aluminum Oxide, Alumina (Al2O3)
Alumina (Al₂O₃) is the most widely used technical ceramic. With a melting point of 2072°C, high electrical insulation, good thermal conductivity (20–35 W/m·K), excellent wear resistance, and strong chemical resistance, it is an indispensable material across industries.
Its low thermal expansion and mechanical strength allow components to endure extreme conditions and mechanical stress. From electronics to mechanical systems, alumina's multifaceted performance makes it a key material in modern industry and technological innovation.
We offer alumina in four purity grades: 95%, 99%, 99.5%, and 99.7%. Use the table below to compare their properties, or browse our product list to find the right part for your application.
Need a specific purity? Check the comparison table for 95% / 99% / 99.5% / 99.7% below, then scroll to Products to find ready-to-buy or custom parts.
More Info About Alumina
Products | Specification | Applications | FAQs | Brochure
| Material | Alumina | ||||
| Properties | Units | AL997 | AL995 | AL99 | AL95 |
| %Alumina | - | 99.70% | 99.50% | 99.00% | 95.00% |
| Color | - | Ivory | Ivory | Ivory | Ivory & White |
| Permeability | - | Gas-tight | Gas-tight | Gas-tight | Gas-tight |
| Density | g/cm3 | 3.94 | 3.9 | 3.8 | 3.75 |
| Straightness | - | 1‰ | 1‰ | 1‰ | 1‰ |
| Hardness | Mohs Scale | 9 | 9 | 9 | 8.8 |
| Water Absorption | - | ≤0.2 | ≤0.2 | ≤0.2 | ≤0.2 |
| Flexural Strength(Typical 20℃) | Mpa | 375 | 370 | 340 | 304 |
| Compressive Strength (Typical 20℃) |
Mpa | 2300 | 2300 | 2210 | 1910 |
| Coefficient of Thermal Expansion (25℃ to 800℃) |
0-6/℃ | 7.6 | 7.6 | 7.6 | 7.6 |
| Dielectric Strength (5mm Thickness) | AC-kv/mm | 10 | 10 | 10 | 10 |
| Dielectric Loss 25ºC@ 1MHz |
- | < 0.0001 | < 0.0001 | 0.0006 | 0.0004 |
| Dielectric Constant | 25º C@ 1MHz | 9.8 | 9.7 | 9.5 | 9.2 |
| Volume Resistivity (20℃) (300℃) |
Ω·cm³ | >1014 2*1012 |
>1014 2*1012 |
>1014 4*1011 |
>1014 2*1011 |
| Long-term Operating Temperature | ℃ | 1700 | 1650 | 1600 | 1400 |
| Thermal Conductivity (25℃) | W/m·K | 35 | 35 | 34 | 20 |
Alumina ceramics stand out for their versatility across a broad spectrum of applications, from high-tech engineering and semiconductor manufacturing to traditional industries and medical prosthetics.
Read more: Everything You Need to Know about Alumina Ceramics
ACM's product formulations are developed to address varied application problems. Many industrial applications push the envelope on specific requirements, leading to the development of new formulations.
| Properties | Unit | Fused Alumina | Reactive Grade Alumina | Ready To Press Alumina (RTP Alumina) | Activated Alumina | |||||||
| Al2O3 Content | % | 95.5 | 99.8 | 98 | 96 | 94 | 92 | 90 | ||||
| Bulk Density | g/cm3 | 3.95 | ~600 | ~1000 | ~600 | ~1100 | ~900 | ~1200 | ~1100 | – | ||
| Grain Size | μm | Customized | Customized | ≈130 | ≈170 | ≈100 | ≈200 | customized | ||||
| Color | – | White | White | White | White | |||||||
| Melting Point | ℃ | 2000 | – | – | – | |||||||
| Hardness | Mohs | 9 | – | – | – | |||||||
| Specific Surface Area | m2/g | – | 0.2-0.5 | 3.5-5 | 2-3 | 6-9 | 6-10 | – | 200-260 | |||

Advanced Ceramic Materials (ACM) is a leading supplier of high-quality alumina ceramic products for various applications. We are happy to provide advice on materials, design, and application. Feel free to contact us with questions about Al₂O₃ or other ceramic materials not listed on the website.
| Chemical Formula | Al2O3 |
| Mechanical | |
| Density | 3.9 g/cm3 |
| Hardness | 17.2 GPa |
| Modulus of Elasticity | 380 GPa |
| Flexural Strength | 380 MPa |
| Compressive Strength | 2450 MPa |
| Poisson's Ratio | 0.23 |
| Fracture Toughness | 4 MPa m½ |
| Electrical | |
| Dielectric Strength | 15 ac V/mm |
| Dielectric Constant | 9.9 (@ 1 MHz) |
| Volume Resistivity | 10^14 ohm-cm |
| Thermal | |
| Coefficient of Thermal Expansion | 7.2 x 10^-6/°C |
| Thermal Conductivity | 37 W/(m*K) |
| Specific Heat | 780 J/(Kg*K) |
| Shock Resistance | 250 °C Diff. |
| Maximum Working Temperature | 1700 °C |