High temperature alumina powder is made of industrial aluminum hydroxide and bauxite, molecular sieve and grinding balls as raw materials. It is calcined in a tunnel kiln for a long time at high temperature. It has a high melting point, excellent mechanical strength, hardness, high resistivity and Thermal conductivity. It can be widely used in industries such as electronic equipment, structural ceramics, refractory materials, wear-resistant materials, and polishing materials. So what effect will excessive sodium oxide content in high-temperature alumina powder have on ceramics?
The most intuitive effect of too high sodium oxide in alumina powder is the density of ceramics, so how does it affect its density?
Na2O is one of the most important indicators of high-temperature alumina micropowder, especially high-temperature alumina micropowder used for ceramic production. At high temperature, Na2O and Al2O3 combine to form a stable sodium peraluminate compound Na2O·1 I Al2O3, which is commonly referred to as β-phase alumina. Its structure is a loose layered structure. Under the conditions, the ability to combine AI2O3 is very strong, the mass ratio of Na2O and A12O3 is 1:18.096, even if a small amount of Na2O exists, a large amount of β-phase A12O3 will be formed, thus affecting the density of ceramics. Moreover, this compound has a high conductivity, reaching 10 ~ S·cnl ~ at 300°C, which affects the electrical properties of the ceramic substrate. Therefore, the high-temperature alumina powder used in the production of ceramic substrates must be low-sodium alumina products, that is, high-temperature alumina powder with a Na2O content of less than 0.1%.
