Alumina99%

99% alumina ceramic is a high-purity, high-performance advanced ceramic material with an aluminum oxide (Al₂O₃) content between 99% and 99.9%. It is considered a "high-end product" in the industrial ceramics industry and is the preferred choice when 95% alumina fails to meet stringent performance requirements. Its microstructure primarily consists of corundum (α-Al₂O₃) grains with minimal intergranular phases. This high purity and density are the root of its exceptional performance.

Composition and Manufacturing:

• Main Component: ≥99% α-Al₂O₃ (corundum phase).
• Additives: Typically, a very small amount (0.1% - 1%) of magnesium oxide (MgO) or other sintering aids is added.
• Function: Inhibits excessive grain growth and promotes sintering densification, resulting in a more uniform and dense microstructure, further enhancing the material's mechanical strength and thermal properties.
• Manufacturing Process: Similar to 95% alumina, but with stricter control requirements for raw material purity and sintering process (temperature, atmosphere) to ensure high purity and density.

99% alumina significantly outperforms 95% alumina in almost all key performance indicators.

Material Properties of 99% Alumina (Compared to 95% Alumina)

Features	99% Alumina	95% Alumina	Advantages
Purity and Density	≥99% Al₂O₃, 3.85-3.95 g/cm³	~95% Al₂O₃, 3.6-3.75 g/cm³	The denser structure and extremely low porosity hinder crack propagation and media penetration.
Mechanical Strength	Flexural Strength: 350-400 MPa	Flexural Strength: 300-350 MPa	Its higher strength allows it to withstand greater mechanical loads and stresses.
Hardness and Wear Resistance	Vickers Hardness: ~1600 HV	Vickers Hardness: ~1500 HV	Stronger and more wear-resistant, they significantly extend their lifespan in harsh abrasive environments.
Thermal Conductivity	28-35 W/(m·K)	20-25 W/(m·K)	Thermal conductivity is improved by approximately 30%, resulting in enhanced heat dissipation and suitable for high-power applications.
Electrical Insulation	Volume Resistivity: >10^14 Ω·cm Dielectric Loss: Lower	>10^14 Ω·cm	It offers more stable insulation performance and lower dielectric loss at high temperatures and high frequencies.
High-Temperature Performance	Higher high-temperature strength and creep resistance	Good	With less glass phase, it is less susceptible to softening at high temperatures, resulting in more stable performance.
Surface Properties	Can be polished to mirror-quality (Ra < 0.1 μm)	Can be polished to 0.2-0.4 μm	The smoother surface provides improved airtightness and a lower coefficient of friction when used in precision sealing applications.
Corrosion Resistance	Excellent (except for hydrofluoric acid and hot concentrated alkali)	Good	The high purity and low porosity make it more resistant to corrosive media.

99% alumina ceramics are used in applications requiring the highest reliability, durability, and performance due to their exceptional performance.

1. High-end Electronic Packaging and Semiconductors

• Applications: Ceramic packages (for integrated circuits, laser diodes, and radio frequency modules), high-power LED substrates, and jigs and carriers in semiconductor process equipment.
• Reasons: High thermal conductivity facilitates chip heat dissipation; high insulation and low dielectric loss ensure signal integrity; and high purity and density ensure vacuum sealing, preventing chip contamination.

2. High-Performance Mechanical Seals

• Applications: Advanced sealing rings for chemical pumps, heavy machinery, and automotive water pumps (often paired with silicon carbide or cemented carbide).
• Reason: Higher hardness and wear resistance provide exceptionally long life; the mirror-polished surface finish ensures excellent sealing and airtightness.

3. Precision and High-Tech Fields

• Applications: Laser discharge tubes and windows, ion source components, aerospace sensor housings, and high-power sodium lamp tubes.
• Reason: Able to withstand extreme environments (high temperature, high pressure, and corrosion); stable and reliable performance; high purity and low outgassing rates meet high vacuum requirements.

4. High-End Wear-Resistant Components

• Applications: High-quality grinding media (balls, cylinders), linings and components for ultrafine grinding equipment.
• Reason: Extreme hardness and wear resistance maximize equipment life and grinding efficiency; high purity prevents impurity contamination during the production process.

5. Biomedical

• Applications: Wear-resistant components for certain artificial joints and ceramic components for medical surgical tools.
• Reasons: biological inertness, high hardness, resistance to disinfection and sterilization, smooth surface.