High Purity Alumina is a high purity ultra-fine alumina powder (crystal phase mainly α-Al2O3) as the main raw material composed of important ceramic materials. High Purity Alumina because of high mechanical strength, hardness, high temperature, corrosion resistance and other excellent performance by the people's attention.
The preparation of High Purity Aluminas is higher than that of the original powder. It is generally the main raw material of alumina powder with purity> 99.99% crystal phase as α phase. The characteristics of high purity ultrafine alumina powder determine the properties of the final preparation of High Purity Aluminas. In the preparation of high purity alumina powder, the purity of the powder is high, the particle size is small and the distribution is uniform, the activity of the powder is high, and the degree of agglomeration is low. This allows High Purity Aluminas to be produced at relatively low temperatures. Therefore, in order to prepare High Purity Aluminas, first to prepare high purity alumina powder.
After the high purity alumina powder was obtained, it was prepared into a good green body, and the High Purity Alumina was prepared according to the requirements and cost of the product. At present, the commonly used sintering methods include: atmospheric sintering, hot pressing sintering, two-step sintering, discharge plasma sintering, microwave sintering and so on.
The use of atmospheric pressure sintering method, High Purity Aluminas usually need to be higher than 1600 ℃ in the sintering dense, high sintering temperature can lead to abnormal growth of alumina grains, sintered compact density decreased, thus affecting high purity oxidation The performance of aluminum ceramics. Reduce the average size of the powder particles, add the appropriate additives, the use of special molding methods can usually reduce the High Purity Alumina sintering temperature.
High Purity Alumina has excellent mechanical properties. High Purity Aluminas with flexural strength of about 250MPa can be prepared by atmospheric pressure sintering method. The High Purity Aluminas prepared by hot press sintering method can have a flexural strength of 500MPa and a hardness of 9GPa (Mohs hardness ). The use of these properties of High Purity Aluminas can be used as grinding wheels, ceramic nails, etc., of which the most widely used is High Purity Alumina cutting tools and High Purity Alumina balls. Due to the high fracture toughness and thermal shock resistance of high purity oxidation ceramics, it is usually necessary to introduce a second phase, such as ZrO2, into alumina to improve the toughness and thermal shock resistance of High Purity Alumina materials.
High Purity Alumina high dielectric loss is small, excellent insulation properties, can be used for the preparation of insulating devices, ceramic substrate and transparent alumina ceramic. Among them, the application of a wide range of transparent alumina ceramics, in many special optical instruments, lighting equipment and space satellite equipment, etc. are widely used.
High Purity Alumina has good biocompatibility, mechanical properties and chemical stability, can be widely used in the preparation of artificial bones, artificial teeth and artificial joints, etc., will be implanted in the human body, will not cause human rejection.
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