Raw materials play an extremely important role in the performance of ceramic products. If unqualified raw materials are used, high-quality ceramics cannot be obtained even with advanced technology. Generally, for Al2O3 ceramics (also applicable to other ceramics), the following situations should be understood:
Chemical composition: including purity, type and content of impurities, stoichiometric ratio, etc.;
Particle size: including powder diameter, particle size distribution and particle shape, etc.;
Structure: including crystal morphology, stability, cracks, density and porosity, etc.
The chemical composition of the powder is related to whether the various physical properties of Al2O3 ceramics can be guaranteed. The impurities in the material also have different degrees of influence on the sintering process. Although impurities are not necessarily harmful, there are usually certain purity requirements for powders. Powders that are not pure enough should be avoided or used with caution. Particle size and structure mainly determine the density and formability of the green body. The smaller the particle size and the more incomplete the structure, the greater its activity and the more conducive to sintering. The raw materials used in Al2O3 ceramics can be roughly divided into two categories: mineral raw materials and chemical products. Mineral raw materials mainly refer to raw ore, that is, items directly from nature, such as corundum (Al2O3) ore. Since natural minerals contain more impurities, they must undergo a set of processing processes before use, such as sorting, crushing, and panning. Panning usually uses water as a suspension, and after stirring and sinking, it can remove coarse particles and impurities with higher density, and can also remove some water-soluble impurities. Organic impurities are usually light in weight and easy to float or can be removed by high-temperature calcination. Other mineral raw materials need to be processed and refined, such as refining Al2O3 from bauxite, etc. These are often completed by specialized manufacturers, and their products are then used by ceramic factories. Chemical products are usually materials obtained by chemical refining and purification, and there are also multiple grades, and their impurity content must usually be indicated. This type of product can often be used directly, or it can be formulated after a little drying and other treatments.
It is worth noting that there should be a reasonable requirement for the purity of raw materials, and we should not blindly pursue excessive purity to cause economic waste. Inexpensive raw materials should be used as much as possible while meeting product performance requirements. Impurities are not necessarily harmful. Some are harmless, and some are even beneficial and can counteract other harmful impurities. For example, some impurities can form eutectics with Al2O3 and promote sintering, so analysis should be made according to specific circumstances, especially when changing the batch number or origin of raw materials, in addition to paying attention to its purity, you should also pay attention to the type and content of impurities, analyze the possible impact on the product, and confirm it through small batch tests.
Edgetech supplies alumina ceramic products with purities ranging from 95%~99.5%, and can also process customized products according to your drawings. We use advanced equipment and exquisite craftsmanship to make each product, and strictly inspect and control it layer by layer to provide you with the best quality ceramic products.