Alumina ceramics is a structural ceramic material with a-Al2O3 as the main crystal phase. Because of its high melting point, high hardness, heat resistance, corrosion resistance, and electrical insulation properties, it can be used under harsher conditions . The price of alumina ceramics is low, and the production process is mature. It is currently one of the ceramic materials with the largest output and the most widely used. It is mainly used in the fields of cutting tools, wear-resistant parts and bioceramics. In addition, it is also widely used in energy, aerospace, chemical, chemical and electronic fields.
However, due to the low toughness and brittleness of ordinary alumina ceramics, its application fields are limited. In addition, the high sintering temperature is also a major reason for its limited application. To obtain ceramic materials with higher hardness and crystallinity, sintering must be performed at a relatively high sintering temperature, which will inevitably lead to an increase in energy consumption.
In recent years, due to the higher and higher requirements for material properties, people have proposed various methods to improve the properties of alumina ceramics, including hot pressing sintering, spark plasma sintering, microwave sintering and adding additives. After taking some new measures, the performance of alumina ceramics in terms of bending strength and hardness has been greatly improved.
Since the last century, nanotechnology has developed vigorously, and various nanomaterials have come out continuously. The progress of nanometer science and technology has had a profound impact on the alumina industry, and has brought a new scientific research direction to the wide application of nanometer alumina. As a special functional material, nanometer alumina has high hardness, high strength, corrosion resistance, Many excellent characteristics such as wear resistance, high temperature resistance, high insulation, high oxidation resistance, etc., are widely used in precision ceramics, bioceramics, chemical catalysts, refractory materials, integrated circuits, and aerospace.
Nano-alumina and alumina are the same substance, but with different strengths. So, what is the effect of adding a certain amount of nano alumina to alumina ceramics?
● A certain amount of nano alumina is added during the preparation of alumina ceramics. During the molding process, the nano powder can be fully filled into the voids of the alumina powder to reduce the porosity, increase the strength of the molded body, and facilitate sintering.
● Due to the small size of nano-alumina and high surface activity, adding a certain amount of nano-alumina can effectively increase the diffusion rate on the surface of the blank, reduce the sintering temperature, and increase the degree of densification of the sintered product.
● This is because nano-alumina has a large number of interfaces, provides a short-range diffusion path and a higher diffusion rate, and makes the sintering driving force of the material also increase sharply, which greatly accelerates the entire sintering process and greatly reduces the sintering temperature.
● While reducing the sintering temperature of alumina ceramics, the crystallinity will not be reduced. The so-called crystallinity is the degree of crystallization of the material in a certain regular arrangement of atoms during the sintering process, that is, the percentage of the mass or volume of the crystalline part to the total mass or volume, in other words the proportion of the crystalline area of the product after sintering. The degree of crystallinity is different, the physical and mechanical properties of the material are different, and the electrical and optical properties of the material are also affected by the degree of crystallinity to a considerable extent.
● Improve the hardness of alumina ceramics.
● Improve the strength of alumina ceramics.
● The modulus of elasticity of alumina ceramics is increased to improve toughness.
In comparison, the physical properties of pure nano alumina ceramics are much better than ordinary alumina ceramics, but the preparation process of nano alumina ceramics is complicated and the cost is higher. Moreover, alumina ceramics themselves have very excellent properties. In some cases, some nano-alumina can be selectively added to improve performance, which not only guarantees product quality, improves production efficiency, but also reduces production costs.
