Calcined aluminum oxide powder, commonly known as alumina (Al₂O₃), is produced by heating aluminum hydroxide or other aluminum compounds at temperatures above 1,000 °C. This high-temperature treatment removes bound water and transforms the material into a crystalline form with superior hardness, thermal stability, and chemical inertness. As a result, calcined alumina serves as a cornerstone material in industries ranging from refractory linings to advanced ceramics.Get more news about Calcined Aluminum Oxide Powder,you can vist our website!

Production Process
The production of calcined alumina begins with the Bayer process, which refines bauxite ore into aluminum hydroxide. After purification, the hydroxide is subjected to controlled high-temperature calcination. Key steps include:

Drying at 100–200 °C to remove free moisture

Pre-heating at 400–600 °C to decompose organics

Calcination at 1,100–1,200 °C for phase transformation

Cooling under inert atmosphere to avoid moisture uptake

Precise temperature ramp rates and hold times determine the final phase composition, specific surface area, and particle morphology.

Material Properties
Calcined alumina exhibits a unique combination of properties:

Hardness: Mohs scale rating of 9, second only to diamond

Density: Typically 3.9–4.0 g/cm³ for α-phase alumina

Thermal Stability: Retains strength up to 1,800 °C

Chemical Resistance: Inert to most acids and alkalis

These characteristics stem from its tightly packed oxygen and aluminum lattice, which also imparts electrical insulation and excellent wear resistance.

Particle Characteristics Table
Below is a comparison of common grades of calcined alumina powder:

Grade Median Particle Size (µm) Surface Area (m²/g) Phase Purity (%) Typical Application
Coarse 40–80 0.5–1.0 95–97 Refractory castables
Standard 5–20 1.5–3.0 98–99 Ceramic substrates, abrasives
Fine 1–5 4.0–6.0 ≥99.5 Precision ceramics, polishing
Ultra-fine <1 8.0–12.0 ≥99.9 Electronic ceramics, catalysts Key Industrial Applications Calcined alumina powder finds its way into a spectrum of applications: Refractories: High-temperature linings for furnaces and kilns Ceramics: Substrates for electronic components, spark plugs, and cutting tools Abrasives: Grinding wheels, sandpapers, and blast media Catalysts and Supports: Substrate for petrochemical catalysts Polishing Media: CMP (chemical-mechanical planarization) slurries for semiconductor wafers Its versatility stems from the ability to tailor phase content and particle size to specific performance requirements. Quality Control and Testing Ensuring consistent performance requires rigorous quality control: X-ray diffraction (XRD) to verify α-phase purity Laser diffraction or BET analysis for particle sizing and surface area Titration or ICP analysis for trace impurity levels (Si, Fe, Na, Ti) Hardness and bulk density measurements Manufacturers often adhere to ISO 9001 systems and industry-specific standards to guarantee batch-to-batch uniformity. Environmental and Safety Considerations While alumina is chemically inert, handling ultra-fine powders poses inhalation risks. Key safety measures include: Local exhaust ventilation and high-efficiency particulate air (HEPA) filters Personal protective equipment (PPE): respirators, gloves, and protective clothing Dust suppression in bulk handling areas From an environmental standpoint, energy consumption during calcination is significant. Advances in regenerative kilns and waste heat recovery systems help reduce the carbon footprint of production. Future Trends and Innovations Research continues to expand the horizons of calcined alumina powder: Nano-engineered alumina with tailored morphologies for specialty catalysts Surface-coated alumina for improved bonding in composites Hybrid materials combining alumina with ceramics like silicon carbide for ultra-high-temperature applications Digital control systems and machine-learning optimization of calcination recipes to lower energy use and improve yield As new applications emerge, the demand for customized alumina grades with precise microstructures will only grow.