The finer the alumina ceramic powder, the more defects and the more active it is.Small particles can also disperse stress concentration caused by different linear expansion coefficients of corundum and glass phase at grain boundary, reducing the risk of cracking.
Fine grain will also hinder the development of microcrack, not easy to cause transgranular fracture, is conducive to improving fracture toughness.In addition, it can also improve the wear resistance of the material.Therefore, it is important to reduce the particle size of Al2O3 powder to prepare Al2O3 products with high performance.At present, there are two kinds of methods to prepare superfine active easily sintered alumina powder: mechanical method and chemical method.
The mechanical method is to refine alumina powder under the action of mechanical external force.The commonly used crushing technologies are ball grinding, vibration grinding, sand grinding, gas grinding, etc.
Wet chemical method is an important method for the preparation of ultrafine and high purity powders, among which sol-gel method is more mature.Wet chemical method can reach nanoscale powder particle size and narrow particle size distribution, high chemical purity, crystal defect, so the chemical powder surface energy and reactive powder is much higher than that of mechanical method, is made of super fine powder as raw material, not only can significantly reduce the sintering temperature of the alumina ceramics (reduce), and can obtain high microcrystalline high-strength aluminum material
