Differences between white corundum and brown corundum
White corundum and brown corundum are both fused aluminum oxide raw materials. They are commonly used in industries such as abrasives, refractory, blasting & grinding, and abrasion. However, there are many differences between them.
The differences between white corundum and brown corundum are in the following aspects:
Item | White corundum | Brown corundum |
| Raw material | Aluminum oxide powder produced by the Bayer process | Calcined natural bauxite ore |
| Production technology | Electro fusing | Electro fusing |
| Fusing equipment | Electric arc furnace (fixed furnace and tilting furnace) | Electric arc furnace (fixed furnace and tilting furnace) |
| Characteristics | Sharper, higher purity, better self-sharpening, smaller crystal size. | Higher toughness, lower cost. |
| Tilting furnace and fixing furnace difference | The smelting of white corundum in fixed furnaces is more complete, and the bottom or cover parts containing impurities have been removed. Fixed furnace white corundum has better toughness. All the white alumina blocks from the dumping furnace have entered the crushing and screening stage. | Brown corundum is divided into different grades based on the alumina content after being melted into blocks in both tilting and fixed furnaces. Due to the large amount and specific gravity of impurities in bauxite, the impurities in brown corundum smelted in the tilting furnace are all located at the bottom of the furnace, resulting in higher purity of the sorted primary block. The toughness and physicochemical indicators of the tilting furnace are also better than those of the fixed furnace brown corundum. |
| Chemical composition | Al2O3: 99-99.8% | Al2O3:93-96% |
| Main impurities | Na2O,SiO2 | TiO2,SiO2, Fe2O3 |
| Quality level | A grade white corundum is min 98.5% purity. Most lower-purity ones are recycled materials. | Brown corundum levels including A, B, C according to the Aluminum oxide content. |
| Color | White | Brown(coffee brown) |
| Mohs hardness | 9.0 | 9.0 ( A Grade) |
| Vicker hardness | 2200-2400 kg/mm2 | 2000-2200 kg/mm2 |
| The limit of using temperature | 1900 ℃ | 1850 ℃ |
| Melting point | 2250 ℃ | 2200 ℃ |
| Specific gravity | 3.95g/cm3 | 3.9g/cm3 |
| Volume density | 3.55-3.6g/cm3 | 3.8-3.9g/cm3 |
| Bulk density | 1.55-1.95 g/cm3 | 1.5-1.9g/cm3 |
| Uses | 1. Abrasives: mainly for bonded abrasives. 2. Sandblasting and grinding: Surface treatment passivation to increase surface roughness. Used for materials such as aluminum alloy, stainless steel, glass, etc., pollution-free. 3. Wear resistance: Wear-resistant coatings, wear-resistant powders, etc. 4. Fillers in coating and paints. 5. Alumina Ceramics. 6. Refractory and casting. | 1. Abrasive: bonded abrasives and coated abrasives. 2. sandblasting and grinding: sandblasting for rust removal, large-scale sandblasting, used for metal and iron products. 3. Anti-slip flooring. 4. Deburring the PCB boards. 5. Grade C brown corundum can be used for water jet cutting. 6. Refractories. |
| Avaible grits | 8#-220#,240#-10000#, 0-1-3-5-8mm,320F,220F,100F | 12#-220#,240#-2000#,0-1-3-5-8mm,320F,220F,100F |
