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Sintering characteristics of activated alumina powder

wallpapers Industry 2020-08-18
The sintering process refers to the transfer of substances between particles when the surface tension is not neglected. The purpose is to cause the powder to bond, thereby increasing the strength of the sintered body. Figure 1 is a schematic diagram of powder sintering.
 
For a long time, alumina powder has been widely used in high-temperature fields due to its high strength, strong corrosion-resistance, and high hardness. However, because alumina belongs to the ion-bonded crystal type, the crystal type is significant. The structure is stable, so a certain amount of heat energy must be provided to achieve sintering. At present, refining raw material particles is one of the main methods to reduce the sintering temperature. This is because when the powder's size is smaller, the powder's surface energy and surface activity will be more significant. When the surface energy of the powder is greater than the grain boundary energy of the polycrystalline sintered body, the surface energy and grain boundary energy of the dust will have a gradient, which becomes the driving force for sintering. After the sintering is completed, there is only grain boundary energy inside the material. This substitution effect can keep the state of the equipment constant. Activated alumina powder is made by calcining industrial alumina. It is a superfine ground product.

The particle size D50 is generally between 0-2um and has the following properties:
(1) Smaller particles can quickly react with other chemical components inside the material, and the new mineral phase generated by the reaction is beneficial to improve the service life of the content;
(2) Smaller particle size provides high specific surface area and high activity to particles;
(3) Excellent filling performance;
(4) The smaller particle size can effectively fill the pores between large particles in different particle gradations, thereby reducing the water demand of the castable and improving the fluidity of the sample;
(5) Strengthen the ceramic bonding of the matrix to enhance the corrosion resistance, wear-resistance, and mechanical strength of the sample. Zhao Huizhong and others optimized the structure and performance of the material by adding nano-sized powders to the castable. The results showed that adding nano-Al2O3 to the corundum castable system can reduce the sintering temperature by 100-200℃. After the heat treatment at the same temperature, the average temperature flexural strength of the sample with nano Al2O3 is higher.

Trunnano is one of the world's largest alumina manufacturers. If you are interested, please contact Dr. Leo, email: brad@ihpa.net.

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Tag: alumina,Trunnano