The Effect of Preparation Technology on Properties of Zirconia Ceramic Materials

The performance of zirconia ceramic materials depends on their internal structure. Only by changing the internal structure of zirconia ceramic materials can the purpose of changing or controlling their performance be achieved. The preparation and processing technology of zirconia ceramic materials often play a decisive role in the material's performance. The relationship between material structure, preparation and processing technology, and performance is represented by a tetrahedron. The vertices of the tetrahedron represent the composition, structure, preparation and synthesis/processing technology, inherent performance, and usability of the material. In the process of advanced ceramic preparation, among many factors that affect the performance of ceramic products, the quality of ceramic powder plays a decisive role.

The particle size of zirconia ceramic powder determines its application range, and different industries have different requirements for the particle size of the powder. Powder materials used in industries such as civil engineering and water conservancy generally have a particle size above LCM; Departments such as metallurgy, gunpowder, and food use powder with a particle size of 40Um~1cm; The particle size of the powder used in the glass industry is O· 15~()· 8mm; The particle size of powder in the cement industry ranges from 0.08 to 0.2nlrTl; The particle size of the raw material powder for refractory materials is 0· Below 088mm; The powder used in ceramic production is finer, approximately below 0.06mm; In recent years, research on nanomaterials has been very hot, with particle sizes ranging from a few nanometers to several tens of nanometers. This shows the importance of powder preparation technology.

Zirconia ceramic powder mainly affects the performance of the material through the following aspects.

(1) The presence of impurities in pure powders can greatly affect the performance of products. For example, the oxygen content in non oxide ceramic powders can seriously affect the high-temperature performance of materials. Some trace impurities in functional ceramics can greatly improve or worsen their performance, such as alkali metal oxides (Naz()) that can reduce the electrical insulation of ceramics.

(2) The particle size of the powder has a significant impact on the sintering process and the performance of the product. Due to the fact that the driving force of sintering is the surface energy of the particles. At a certain sintering temperature. The finer the powder, the greater the surface energy, and the faster the sintering rate. On the other hand, if the raw materials are very fine, have high surface activity, have a short diffusion path during sintering, and have many grain boundaries, it will promote the diffusion of pores, increase the densification speed, and ultrafine powder can be sintered at lower temperatures, thus obtaining high-density and fine-grained ceramic materials. However, if the powder is too fine, it often brings new problems, such as the finer the particles, the more serious the phenomenon of powder agglomeration. In addition, it can also lead to low powder stacking density and difficulty in forming.

(3) If there is a significant difference in particle size during sintering, it will cause abnormal growth of the product particles, which will seriously affect the performance of the material. However, spherical or equiaxed ceramic powders with narrow particle size distribution can avoid the occurrence of these defects.

(4) Due to the different densification behaviors of powders with different crystalline forms, or the different requirements for the crystalline form of sintered ceramic materials, the powder is often required to have a specific crystalline form. For Si3N4 powder, the more a phase is required, the better.

(5) Agglomeration conditions: Agglomeration will lead to uneven density of the formed material. During sintering, agglomeration takes precedence over other particles to densify, resulting in poor ceramic performance and inability to obtain highly uniform and dense ceramic materials. Therefore, high-tech ceramics require powders to contain no or less aggregates, especially hard aggregates.

The above requirements for zirconia ceramic powder are idealized, but in reality, they are difficult to fully meet. Some requirements sometimes constrain each other, and people can only continuously innovate and improve powder preparation techniques and methods in practice, strive to approach these idealized requirements, and find their equilibrium points in complex mutual constraints. Therefore, learn and master the characteristics of special ceramic powders, and

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