Zirconium corundum is a mixed material of zirconia and alumina, but it does not simply mix zirconia and alumina, but uses alumina and zirconia as raw materials to smelting at high temperature above 1900℃ in an electric arc furnace. The eutectic formed by melting and then rapidly cooling. Finding a eutectic is what we often call zirconium corundum.
According to the content of zirconium oxide, zirconium corundum is divided into 25 Zironia(AZ25) and 40 zirconia (AZ40).
AZ40 is zirconium corundum with 40% zirconia content. According to theoretical calculations, only when the content of zirconia is 40%, the eutectic of zirconia and alumina can achieve a perfect homogeneous structure. When the zirconia content is greater than 40%, the zirconia separation phase accounts for a larger proportion. When the zirconia content is less than 40%, the alumina separation phase accounts for a larger proportion.
Here are properties of Zirconium corundum:
1. Microcrystalline structure and crystal size
The smelting and production of zirconium corundum requires rapid cooling to obtain abrasive particles with smaller crystals. Therefore, compared with traditional abrasives such as white corundum and brown corundum, it has the characteristics of high wear resistance. The microcrystalline structure and crystal size are also the main indicators that determine the quality of AZ-40 zirconium corundum. Through the microstructure, we can observe the homogeneous structure in the eutectic and how much the separated phase is. At the same time, we can also see the separated phase is zirconia or alumina. The smaller the crystal size, the more units involved in grinding, and the more duarble the grinding is.
How tiny of the crystal size of zirconia alumina depends on the cooling speed after abrasive smelting. If the cooling process is fast, the eutectic structure of the abrasive is better and will get less phase separation is small. Thus the crystal size will be smaller.
2. Zirconia content
There are many zirconium raw materials for the production of zirconium corundum. Raw material usually goes zircon sand and other zirconium materials. AZ25 has low zirconia content and relatively economical. It is suitable for making heavy-duty grinding wheels, blasting on steel castings & super-hard steel & stone, and wear-resistant products manufacturing. AZ40 has high zirconia content and high bulk density. It is suitable for the production of cutting discs and coated abrasive tools such as steel paper sand discs, fiber wheels, nylon polishing wheels and other products.
3. Particle Distribution
The bulk density of zirconium corundum is also closely related to the production process. The grain size of zirconium corundum produced by the Barmac ball mill is more rounded, the bulk density is high, and the wear resistance is better reflected.
4. Bulk density
| Item | AZ25 | AZ40 |
| Specific Gravity | 4.30g/cm3 | 4.60g/cm3 |
| Bulk Density | 1.90-2.30g/cm3 | 2.15-2.45g/cm3 |
The toughness of Zirconia Alumina is 14-18 times that of brown corundum. Especially for high pressure grinding, the toughness and wear-resistance are key factors in the application. According to the feedback from Haixu Abrasives customers, the grinding discs produced by zirconium corundum can significantly improve the grinding of super-hard steel.
The high-quality zirconium corundum produced by Haixu Abrasives uses desiliconized zirconium and alumina as the main raw materials. The cooling process is improved on the basis of the original traditional cooling, which is conducive to the rapid formation of small crystals. The crystallite size of the high-quality zirconium 40 abrasive can reach 11um. The quality of our Zirconia corundum can rival with famous brand in the world.
