White fused alumina is also called white fused alumina. It is an artificial abrasive material made by the fusing process. WFA is a high-grade refractory raw material and a commonly used wear-resistant material. The main crystal phase of fused white corundum is α-Al2O3 (Alpha Aluminum oxide), the color is white and flawless.
The production process of white fused alumina:
The production process of white fused alumina is a process of melting and recrystallizing high-purity industrial alumina powder at high temperatures up to 2250 °C. Unlike brown fused alumina, whose electrofusion is a process of oxidation and reduction to generate alumina. Industrial alumina powder is also made of bauxite. The content of Al2O3 is generally 98.5-99%. In addition, there are a small number of impurities such as Na2O, SiO2, and Fe2O3 in the alumina powder. The electro-fusing smelting can refine the powder to get white-fused alumina. However, the impurities cannot be completely removed. In the molten process, sodium oxide and aluminum oxide will generate β-Al2O3 (Na2O·11Al2O3). And it will increase as the content of Na2O increases. β-Al2O3 has a low melting point, low bulk density, and low hardness. When the white fused alumina blocks are cooled and crystallized, β-Al2O3 will precipitate in the upper part of white fused alumina lumps. That will seriously affect the refractory performance and hardness of the white-fused alumina material.
Thus, the production of fused white corundum must strictly control the content of sodium oxide. Selecting low-sodium alumina powder as the raw material can improve it. Furthermore, adding auxiliary materials that promote the volatilization of Na2O for smelting is also a general method to reduce Na2O.
The properties of white fused alumina:
High hardness: Mohs hardness is 9.0, Vickers hardness(HV) is 2000-2200.
Excellent toughness: TakeWFA F120 for example, the compressive strength of white fused alumina is 100KN/cm2.
High self-sharpening ability: the crystal shape of white fused alumina is Angular shape. The particle can get a new sharp edge after grinding. So WFA has a very aggressive grinding ability.
High-temperature resistance with low thermal conductivity and low coefficient of linear expansion. So it can resist thermal shock.
