1. The influence of raw material powder
The most important raw material for alumina wear-resistant ceramics is high-purity alumina powder. Its performance and content have a great influence on alumina wear-resistant ceramics. The ceramic powder will inevitably introduce impurities during the preparation process, and the organic impurities will be burned during the sintering process, forming irregular pores during the densification process; the inorganic impurities will react with the ceramic powder at high temperature or in the matrix Formation of microcracks. These impurities have a significant effect on the densification of alumina ceramics. The particle size of the raw material powder also has a great influence on the performance of the product. Only when the raw material is fine enough, the final sintered product can form a microcrystalline structure, which makes it have good wear resistance. Therefore, high-purity, fine-grained alumina powders are an important prerequisite for the preparation of wear-resistant alumina ceramics.
2. Influence of molding method
Production practice and a large number of studies have shown that low-porosity, high-density alumina ceramics have excellent structural properties. High density means that the crystal grains in the ceramic body are closely arranged, and it is not easy to develop a destructive breakthrough point when subjected to external environmental loads or corrosive substances.
In order to obtain high density ceramic body molding method is crucial. Alumina wear-resistant ceramics can generally be formed by dry pressing, isostatic pressing, hot die casting and other methods. Different sintering methods have different characteristics and have different effects on the sintering properties and microstructure of alumina ceramics.
Products with miscellaneous shapes are generally processed by grouting or hot-press casting, and products with simple shapes are formed by dry pressing.
3. Sintering effect
Sintering is a key stage in the preparation of ceramics, and the sintering atmosphere has a great influence on the preparation of ceramic materials. Excessively high firing temperature or excessively long holding time will promote the growth of crystals, making fine raw materials develop into coarse grains at high temperature, and the liquid phase content will increase. This not only reduces strength, but also reduces wear resistance. Of course, if the temperature is too low, the sintered body will not be dense, and the wear resistance of the product will not be good.
Excellent electric sintering furnace sintering can precisely control the heating, holding and cooling process, which plays an important role in improving the wear resistance of ceramics, but the sintering cost and refractory material consumption of electric kiln are higher than those of coal mines.
4. Combustion accelerant
Appropriate sintering aids reduce the temperature during sintering, improve the microstructure of ceramics, and improve the mechanical properties, thereby effectively improving the wear resistance of alumina wear-resistant ceramics.
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Post time: May-28-2023