What is White Fused Aluminum Oxide Polishing Powder?
White Fused Aluminum Oxide (WFAA) polishing powder is a high-purity, synthetic abrasive material. It is produced by fusing calcined alumina (Al₂O₃) in an electric arc furnace at temperatures above 2000°C, followed by controlled crushing, milling, and precision grading into fine or ultra-fine powders.
Primary Composition: >99% α-Al₂O₃ (corundum crystal structure).
Key Property: Exceptional hardness (9.0 on the Mohs scale).
| Typical Chemical composition | |
| AL2O3 | 99.3%min |
| SiO2 | 0.06% |
| Na2O | 0.3%max |
| Fe2O3 | 0.05%max |
| CaO | 0.04%max |
| MgO | 0.01%max |
| K2O | 0.02#max |
| Typical physical properties | |
| Hardness: | Mohs:9.0 |
| Maximum service temperature: | 1900 ℃ |
| Melting Point: | 2250 ℃ |
| Specific Gravity: | 3.95g/cm3 |
| Volume density | 3.6g/cm3 |
| Bulk density(LPD): | 1.75-1.95 g/cm3 |
| Color: | White |
| Particle shape: | Angular |
| Available size: | |
| FEPA | F230 F240 F280 F320 F360 F400 F500 F600 F800 F1000 F1200 F1500 |
| JIS | 240# 280# 320# 360# 400# 500# 600# 700# 800# 1000# 1200# 1500# 2000# 2500# 3000# 4000# 6000# 8000# 10000# |
2. Key Characteristics & Advantages
High Hardness & Sharpness: Provides efficient material removal and generates a fine, consistent scratch pattern, leading to a superior surface finish.
High Chemical Purity (>99% Al₂O₃): Contains minimal metallic impurities (e.g., iron oxide). This makes it non-contaminating and ideal for applications where staining or chemical reaction is unacceptable.
Friability: The grains have a self-sharpening characteristic. They fracture into smaller, sharp fragments under pressure, maintaining cutting efficiency and preventing dulling.
Chemical Inertness: Highly stable and resistant to acids and alkalis, ensuring it does not react with workpiece materials or polishing fluids.
Thermal Stability: Maintains its structure and hardness at high temperatures generated during polishing.
3. Manufacturing Process
Fusion: High-purity calcined alumina is melted in an electric arc furnace.
Cooling & Ingot Formation: The molten mass is cooled slowly to form large ingots of solid, crystalline alumina.
Crushing & Milling: The ingots are crushed, ball-milled, or jet-milled into a coarse powder.
Classification & Grading: The powder undergoes rigorous sizing processes (e.g., air classification, sedimentation) to separate it into very specific, narrow particle size distributions (often from coarse grits down to micron or sub-micron levels for polishing).
Treatment: May be washed with acid to remove any residual surface impurities.
4. Primary Applications
WFAA polishing powder is the go-to abrasive for finishing hard, high-value materials where surface integrity and purity are paramount.
Optical & Precision Lenses: Polishing of glass, crystals, optical elements, and lenses due to its purity and ability to achieve excellent clarity and low surface roughness.
Semiconductor & Wafer Processing: Critical for silicon wafer back-grinding, sapphire substrate polishing, and other processes requiring contamination-free abrasion.
Technical Ceramics: Finishing of alumina, zirconia, silicon carbide, and other advanced ceramics used in medical, aerospace, and industrial components.
Metal Polishing: Used for stainless steel, titanium, hardened steel, and other alloys to achieve a high-luster, flawless finish without embedding impurities.
Stone & Gem Polishing: Final polishing stage for granite, marble, and precious gemstones like sapphires and rubies.
High-End Wood Finishing: Used in some sealed wood coatings for burnishing.
White Fused Aluminum Oxide Polishing Powder is a high-purity, high-performance synthetic abrasive prized for its hardness, sharpness, and chemical cleanliness. It is the premier choice for precision polishing of optics, semiconductors, technical ceramics, and high-grade metals, where achieving a flawless, contaminant-free surface is the primary goal. Its key advantage lies in providing aggressive yet controllable cutting action while maintaining exceptional workpiece purity.