To judge the quality of brown aluminum oxide, a systematic evaluation is required based on the appearance characteristics, physical properties, chemical composition and industry specifications. The specific standards are as follows:
1. Appearance characteristics of brown aluminum oxide
Color
High-quality features: dark brown, dark brown or tan, uniform color, good light transmittance (transparent or slightly blue when observed in sunlight)
Inferior features: abnormally bright, black, rose red, may contain impurities or high iron content Particle shape The particles should be regular hexagonal or spherical, uniform in size, without lumps or impurities; the finer and more uniform the particles, the higher the grinding efficiency.
2. Brown aluminum oxide physical properties test
Hardness test
Use a hardness tester (Vickers or Rockwell) to test, and the compressive strength must meet the standard; simple test: hand-press the particles and place them on white paper. If they break easily, it means the hardness is insufficient.
Impurity adsorption
Use a magnet to adsorb the sample. The less magnetic material, the higher the purity of the alumina and the lower the impurity content (such as iron).
Wear resistance and ash content
Wear resistance can be compared with standard samples through a wear tester; ash content test: it is better if there is no white floating matter on the water surface after soaking in clean water.
3. Analysis of Chemical Composition of Brown aluminum oxide
Alumina (Al₂O₃) content
First-grade: Al₂O₃ ≥ 94-95% (some high-purity products ≥ 96%); Second-grade: about 90-80%; Third-grade: lower content
Imponents such as iron (Fe) and silicon (Si) must be strictly controlled at a low level.
4. Price Reasonability
The price of high-quality products is relatively high (reference: the market price of first-grade products is 4500-5500 yuan/ton), and low-priced products may be mixed with secondary raw materials.
Brown aluminum oxide quality grading standard reference
|
grade |
Al2O3 content |
Typical features |
|
First-class product |
94~95% |
Dark brown and translucent, uniform particles, high hardness |
|
Secondary |
90%~80% |
Slightly lighter color, slightly more impurities |
|
Third Grade |
≤75% |
Uneven color, obvious impurities |
Note: In industrial applications, first-grade products are suitable for precision grinding and refractory materials; second-grade/third-grade products are mostly used in general industrial scenarios.
5. Avoidance Guide
Beware of low-price traps: Brown aluminum oxide with black, opaque or rose red color is mostly inferior products with high loss rate.
Verify purity: Require the manufacturer to provide a third-party component test report, focusing on checking Al₂O₃ and impurity content.
