White Aluminum Oxide is a high-purity, synthetic mineral valued in the ceramic industry for its exceptional hardness, chemical inertness, and thermal stability.
| 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: | |
| F8# F10# F12# F14# F16# F20# F22# F24# F30# F36# F46# F54# F60# F70# F80# F90# F100# F120# F150# F180# F220# F230 F240 F280 F320 F360 F400 F500 F600 F800 F1000 F1200 F1500 | |
Its primary roles can be categorized into two main areas: 1) As a functional additive in ceramic bodies and glazes, and 2) As a key abrasive for processing and finishing ceramic products.
1. As a Functional Additive in Ceramic Bodies and Glazes
In this role, white aluminum oxide is incorporated into the ceramic formulation itself, where it acts as a multi-functional performance enhancer.
| Application Area | Primary Function | Benefits and Details |
|---|---|---|
| Reinforcement Filler | Increase Mechanical Strength | White Aluminum Oxide particles act as a reinforcing agent, creating a composite material. They hinder crack propagation, significantly increasing the flexural strength and abrasion resistance of the final ceramic product. |
| Wear-Resistant Ceramics | Enhance Hardness & Wear Resistance | This is critical for ceramics used in demanding applications like industrial liners, nozzles, cutting tools, and tile in high-traffic areas. White Aluminum Oxide drastically improves the product’s lifespan under abrasive conditions. |
| Refractory Ceramics | Improve Thermal Stability | Due to its very high melting point (~2050°C), White Aluminum Oxide is added to refractory bricks, kiln furniture (shelves, posts), and crucibles. It enhances thermal shock resistance (resistance to cracking from rapid temperature changes) and increases the PCE (Pyrometric Cone Equivalent) value, allowing the refractory to withstand higher temperatures. |
| Technical Ceramics | Control Thermal Expansion & Insulation | In advanced technical ceramics (e.g., substrates for electronics, insulators), White Aluminum Oxide’s controlled coefficient of thermal expansion and excellent electrical insulation properties are crucial for reliability and performance. |
| Glaze and Engobe Matting Agent | Create Satin or Matte Finishes | Finely milled White Aluminum Oxide is used in glazes and engobes. By remaining in suspension and not fully dissolving, the fine particles scatter light, creating a desirable satin or matte surface texture instead of a high-gloss finish. |
2. As an Abrasive for Processing Ceramic Products
This is a very widespread and critical application. White Aluminum Oxide’s sharp, blocky grains are ideal for shaping, finishing, and preparing ceramic surfaces at various stages of production.
| Application Area | Process and Details |
|---|---|
| Grinding & Lapping | Precision Machining of Technical Ceramics: White Aluminum Oxide bonded grinding wheels and lapping compounds are used to machine advanced ceramics (e.g., alumina, zirconia) to precise dimensions and tight tolerances. Its hardness allows it to effectively cut these tough materials. |
| Abrasive Blasting (Sandblasting) | Surface Preparation: Used to clean and roughen the surface of ceramic tiles, sanitaryware, or technical components before gluing, painting, or coating. This creates a “anchor profile” that ensures superior adhesion. It can also be used for creating decorative etchings or matte finishes. |
| Polishing | Achieving a High-Gloss Finish: While harder abrasives like diamond are used for coarse polishing, very fine grades of White Aluminum Oxide in polishing compounds are excellent for the final lapping and polishing stages to achieve a mirror-like finish on ceramic substrates, insulators, and decorative items. |
| Tumbling & Deburring | Smoothing Edges: In mass production, ceramic components are placed in vibratory or rotary tumblers with White Aluminum Oxide media. This process smoothly removes sharp edges (deburring) and refines the surface finish. |
Key Properties of White Aluminum Oxide
High Hardness (9 on Mohs Scale): Harder than most ceramic materials themselves, making it effective for grinding and reinforcing.
High Purity (>99% Al₂O₃): Low iron and silica content prevents contamination and unwanted color changes in white or brightly colored ceramics.
Chemical Inertness: Does not react with other ceramic components or glazes at high temperatures, ensuring process stability.
High Melting Point (~2050°C): Remains stable and solid even in high-fire ceramic processes.
Controlled Particle Size: Available in a wide range of precisely graded grit sizes (from coarse grits like F24 to fine powders like F1000), allowing for tailored performance in both additive and abrasive roles.
Good Thermal Shock Resistance: Performs well in the rapid heating and cooling cycles typical of ceramic kilns.