Different sintering methods for different alumina ceramics
First, the sintering method of atmospheric pressure alumina ceramics: in fact, under atmospheric conditions, the whole process of sintering the body, this way in the sintering temperature will be relatively high, so the requirements for the kiln is also high, and the waste of energy is also very large.
Second, the sintering method of hot-pressed alumina ceramics: the temperature is lower than that of normal temperature sintering, and the sintered products can be obtained in the theoretical density of 99%, because the hot-pressed sintering is mainly used in preforming, or the powder is directly loaded into the mold, the whole process is relatively simple.
Third, the sintering method of electric field alumina ceramics: that is, the embryonic body of the ceramic is directly under the action of the DC electric field to complete the entire sintering process.
Fourth, the sintering method of ultra-high pressure alumina ceramics: The entire work of sintering needs to be carried out under pressure above hundreds of thousands of atmospheres.
Fifth, the sintering method of atmosphere alumina ceramics: mainly for the products that are difficult to be sintered in the air, in order to prevent its oxidation, the appropriate gas can be entered into the interior of the furnace to form the required atmosphere effect, and the sintering is completed in this atmosphere.
Most ceramic products are basically white, and the same is true of alumina ceramics. But I do not know why, these ceramic products after a long time of use, will change from white castings to light yellow, is it the alumina ceramic discoloration?
Of course not, the reason why the white alumina ceramics will gradually turn pale yellow, on the one hand, is because after sunlight exposure, its internal composition changes, and this change is irreversible, so the color will also change.
On the other hand, it may be that the alumina ceramics have delixed, resulting in the production of hydrated alumina. In fact, not only ceramic products have this characteristic, other materials will also have, so we can only overcome the phenomenon of discoloration of alumina ceramics by minimizing the influence of external factors.
About alumina ceramics, in addition to the reasons behind its discoloration to figure out, but also to master some of the basic principles of using it to make the shaft, to ensure that the product meets the requirements, can be used normally.
Considering that the material is relatively special, it is necessary to be more careful when designing the alumina ceramic core to reduce unnecessary damage. The content mainly involves the type, size and position of the installation parts, the fixing method of the parts, the nature, direction, size and distribution of the load; Type and size of alumina ceramic bearings; Alumina ceramic shaft blank, manufacturing and assembly process, installation and transportation; A series of factors such as the deformation of the shaft.
In a word, it must be designed according to the specific requirements of alumina ceramic shaft, but on the premise of saving materials and reducing weight, try to use the cross-section shape of equal strength dimension or large section coefficient; And adopt a variety of structural measures to reduce stress concentration and improve strength to further ensure product quality and performance.
