Prelay sand 99.8%-99.9% white aluminum oxide powder F80-F220 for ceramic sintering

Electronic ceramics are ceramic electronic components in the electronics and semiconductor industries. The main materials of electronic ceramics include aluminum oxide, aluminum nitride, silicon carbide, zirconium oxide, silicon nitride, etc. The precision and quality requirements for electronic ceramic structural components and functional ceramics are relatively high, and the sintering process of electronic ceramics is an important part of ensuring ceramic quality. Sintering electronic ceramics not only requires special kiln equipment, but also excellent isolation materials for assistance. High purity 99.8-99.9% white aluminum oxide powder F80-F220 are used as prelay sand in the ceramic green body sintering process.

White aluminum oxide powder with a content of 99.8-99.9% has another name micro sodium white corundum or high purity white electrofused alumina. Using the white corundum powderas an isolation prelay sand placed between the kiln furniture and ceramic green body can prevent sticking. Compared with white corundum powder with a content of 99% -99.5%, high-purity one has the following outstanding advantages:

1. High refractory temperature.

The smelting time for 99.8% -99.9% purity white aluminum oxide is as long as 10 hours. The alumina powder is fully smelted, and its crystal development is complete. The generation rate of β – phase alumina is less than 3%. Therefore, the refractory temperature can reach 1850 degrees, much higher than the 1200 degrees of sintering.

2. Refractoriness under load.

The starting temperature for refractoriness under load of fused alumina sand is 1770 degrees. In fact, the hardness of white corundum decreases with increasing ambient temperature. Normally, the hardness of ordinary corundum sand at 1200 degrees will decrease by 70% compared to at room temperature. High purity white fused aluminum oxide has a much smaller impact on hardness at high temperatures. It is beneficial for providing support to ceramic products during sintering.

3. Thermal stability.

High purity 99.8% -99.9% pure fused alumina sand, with sodium content controlled within 0.1% and low silicon iron content. This is very helpful for the thermal stability of white corundum sand. This type of corundum sand can withstand stable changes during sintering, including repeated rapid cooling and heating. At the same time, it can resist the damage and peeling of materials caused by high temperatures.

4. Excellent high temperature and chemical corrosion resistance.

When electronic ceramics are sintered, both the kiln equipment and the ceramic material itself will produce furnace gas, acidic and alkaline substances, and oxides. High purity fused alumina sand with a crystal phase conversion rate of over 97% has high corrosion resistance to acidic and alkaline substances.

5. Volume stability.

The thermal expansion coefficient of high-purity alumina powder with a content of 99.8-99.9% is very low. Thus,during the sintering process of ceramics, the volume shrinkage and expansion generated are much smaller than those of medium sodium alumina sand. This is crucial for precision ceramics in high-precision industries, as it can avoid deformation caused by the fired material and improve the dimensional accuracy of ceramic parts.

6. Chemical inertness.

High pure white corundum prelay powder has good chemical inertness and will not react with ceramic materials. Ultra low levels of impurities can also prevent adhesion or defects from reacting with ceramics.

7. Even particle size distribution.

The particle distribution of high-purity WFA powder is uniform. The shape is irregular and polygonal, resembling a spherical shape. Moreover, the particles become more round and uniform after reshaping process. Evenly spread on the ceramic firing tool, the difference in the height of the particles is very small. Beneficial for the sintering and forming of ceramics.

The particle size range of White corundum powder F80-F220 is as below:

Based on the above characteristics, high-purity aluminum oxide powder(sand) has advantages that other white corundum do not have for the application of sintered electronic ceramics.