News

What Should You Pay Attention To When Buying White Fused Alumina

When purchasing white corundum, the customer often encounters various white corundum products with different prices, models, and processes. So it is necessary to understand the characteristics of white corundum. Today, we will let you know the 10 points you need to pay attention to when purchasing white corundum based on common uses and processes.

1. Granularity of white corundum:

The general particle size requirements of segment sand white corundum used for refractories are relatively simple. However, with the improvement of the refractory technology, many companies will make more detailed particle size distribution requirements in the section sand interval.

The purchase process of white corundum for abrasives generally only pays attention to the corresponding national standard model and should pay more attention to the particle distribution within the specific particle size range. The same type of white corundum feels too coarse or too fine in actual use. It is related to the particle size distribution control of different factories. Specific reference standards: “GBT 2481.2-1998 National Standard for Micro powder Particle Size F230-F1200″, “GBT 2481.1-1998 National Standard for Coarse Abrasives F4-F220″, “National Standard for Particle Size GBT 9258.3-2000 Micro powder P240-P2500″, “GBT 9258.2-2008 Coarse Abrasive P12～P220》.

2. The Alumina content of white corundum:

The alumina α-Al2O3 in white corundum is the main substance that reflects its high-temperature resistance, wear resistance, hardness, and other properties, so it can be said that the alumina content is the most important indicator of white corundum, and the alumina content is mainly related to the raw material alumina. The quality of the powder is related to the smelting time. “GBT 2479-2008 Ordinary Abrasive White Corundum” stipulates that the Al2O3 content should be above 99.0%.

3. The sodium content of white corundum:

The alumina α-Al2O3 in the white corundum mentioned above is the main material that reflects its high-temperature resistance, wear resistance, hardness, and other properties, while the sodium oxide in the white corundum will produce high sodium aluminum acid during smelting. Reduce the formation of α-Al2O in white corundum and affect the performance of white corundum. Controlling low sodium requires increased smelting time, power consumption, and the use of low-sodium alumina, so the cost will increase. “GBT 2479-2008 Ordinary Abrasive White Corundum” stipulates that the Na content is below 0.40%, while the daily low sodium alumina Na content is below 0.20%.

4. The smelting process of white corundum:

The main smelting methods of white corundum are two methods: dumping furnace smelting and fixed furnace smelting. The essence of the two smelting industries is the process of electro-melting and recrystallization of white corundum, but different processes will cause different characteristics. The white corundum frit produced by the dumping furnace has a high degree of industrialization and a relatively uniform quality; the white corundum frit produced by the fixed furnace has the characteristics of good central quality and unstable external quality, but the long-standing cooling time makes the white corundum in the center. The body density is higher, and fixed furnace white corundum is used exclusively for some special purposes.

5. Bulk density of white corundum:

The bulk density of white corundum can reflect the particle bulk density, porosity, particle shape, particle size composition, and other indicators to a certain extent. In simple terms, white alumina powder with high bulk density has high bulk density, low porosity, rounded particle shape, and dispersed particle size composition. On the contrary, white corundum with low bulk density has low bulk density, high porosity, sharp particle shape, and concentrated particle size composition.

6. The whiteness of white WA

The whiteness of white corundum is measured by a special instrument whiteness meter, but the application has high requirements on the color and gloss of the product, which can be specially proposed. The whiteness of ordinary white corundum is about 90.

7. The cleanliness of WFA

The cleanliness of white corundum corresponds to the turbidity of white corundum, which is measured by a special instrument turbidity meter, which mainly reflects the amount of fine dust attached to the particles. For simple visual inspection, pure water can be poured into the white corundum and stirred to see the turbidity of the water and then make a rough judgment. Washing and pickling processes can improve the cleanliness of white corundum.

8. Hardness of WFA:

The hardness indicators of white corundum are: Mohs hardness (scratch method), microhardness (indentation method), Mohs hardness is about 9, and the microhardness range is 2200-2400kg/mm2

9. The melting point of white corundum:

The melting point of white aluminum oxide is 2250°C, and the maximum operating temperature is 1900°C. Generally speaking, the higher the alumina content of white corundum, the lower the sodium content, the higher the corresponding melting point. It is worth reminding that some factories add aluminum fluoride AlF3 when smelting white corundum to reduce the melting point of alumina in order to save power consumption costs, which will reduce the melting point of the product and other properties.

10. White fused aluminum oxide particle shape:

Different applications will use various shapes such as sharp or rounded or flat particle shapes. It’s related to the crushing process of white corundum, such as tube mill crushing, jet mill crushing, etc. Generally speaking, coated abrasives require sharp particles, sandblasting and consolidation molds require round particles.

Last, you will find that it is not correct to only care about the price in usual. Due to the existence of recycled waste and secondary materials of defective products in production, some factories will give a pretty low price. If you want to know the cost of the factory, the price and power consumption of raw material industrial alumina powder are basically the main cost of white corundum. If the price is lower than this cost, it is impossible to buy real quality white corundum.