How to judge the quality of brown corundum?

To judge the quality of brown corundum, it is necessary to conduct a systematic evaluation based on appearance characteristics, physical properties, chemical composition and industry specifications. The specific standards are as follows:

 

 

Appearance characteristics

 

Color High-quality characteristics: dark brown-red, dark brown or brown-brown, uniform color, good light transmittance (transparent or slightly blue when observed in the sun) Low-quality characteristics: abnormally bright, black, rose red, may contain impurities or excessive iron content.

Particle shape The particles should be regular hexagonal or spherical, uniform in size, without agglomerates or impurities; the finer and more uniform the particles, the higher the grinding efficiency.

 

Physical property test

 

Hardness test Tested with a hardness tester (Vickers or Rockwell), the compressive strength must meet the standard; simple test: press the particles on white paper by hand, and if they are fragile, it means that the hardness is not enough. Impurity adsorption Use a magnet to adsorb the sample. The less magnetic, 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 using a wear tester; ash content test: no white floating objects on the water surface after soaking in clean water are preferred

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Chemical composition analysis

 

Alumina (Al₂O₃) content Grade 1: Al₂O₃≥94-95% (some high-purity products ≥96%); Grade 2: about 90-80%; Grade 3: lower content, impurities such as iron (Fe) and silicon (Si) must be strictly controlled at a low level.

 

Reasonable price

 

High-quality products are expensive, and low-priced products may be mixed with secondary raw materials. Pit avoidance guide

Beware of low-price traps: products with black, opaque or rose red colors are mostly inferior products with high loss rates. Verify purity: Manufacturers need to provide a third-party component test report, focusing on checking Al₂O₃ and impurity content.