Performance characterization and preparation technology of advanced ceramic powders

The performance of advanced ceramic materials is to some extent determined by their microstructure, which depends on the preparation process. As mentioned earlier, the preparation process of advanced ceramics includes three main steps: powder preparation, molding, and sintering. Among them, powder preparation is the foundation. If the quality of the powder used as the foundation is not high, even at a high cost during subsequent molding and sintering, it is difficult to obtain ideal microstructure and high-quality ceramic products. The so-called powder refers to a collection of a large number of solid particles. It represents a state of existence of matter, which is different from gas, liquid, or completely different from solid. Therefore, some people view powder as the fourth phase beyond the three states of gas, liquid, and solid. The quality of powder performance will directly affect the quality of molding and sintering. If the flowability of the powder is poor, severe agglomeration, and the particles are coarse, it is impossible to obtain a uniform, high-density, and defect free green body through molding. Such green bodies will inevitably have a very narrow sintering temperature, which will make it difficult to control the sintering conditions, making it impossible to produce a uniform microstructure, high density, and internal defect free green body A porcelain body with a flat surface. Therefore, as the main raw material of advanced ceramic materials, the performance of powder is crucial for advanced ceramic materials. Therefore, learning and mastering the basic characteristics and preparation methods of ceramic powders is an important prerequisite for preparing high-performance ceramic products.

Kezhong Ceramics generally divides the preparation methods of advanced ceramic powders into two types: mechanical method and synthetic method. The former uses mechanical crushing method to convert mechanical energy into surface energy of particles, and obtains fine particles from coarse particles. This method has simple process, low cost, and is suitable for industrial production. However, impurities are inevitably mixed during the crushing process, and it is not easy to produce fine particles with a particle size below LUM. The latter is a method of obtaining fine particles through the reaction, nucleation, and growth of ions, atoms, or molecules, collected and processed. The characteristics of this method are controllable purity, particle size, good uniformity, and the ability to obtain ultrafine particles. It can also achieve particle recombination and homogenization at the molecular level, making it particularly suitable for the preparation of advanced ceramic ultrafine powders. The synthesis method can usually be divided into solid-phase method, liquid-phase method, and gas-phase method, but the raw materials synthesized by solid-phase method often require mechanical crushing.

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