The influence of nano-alumina on the properties of alumina ceramics

Aluminum oxide ceramics

Alumina ceramic is a kind of a-al2o3 based crystal structure ceramic material, because of its own high melting point, high hardness, heat resistance, corrosion resistance, electrical insulation characteristics, so it can be used in more demanding conditions.  Alumina ceramics, with low price and mature production process, is one of the largest and most widely used ceramic materials, mainly used in the field of cutting tools, wear-resistant parts and bioceramics.  In addition, it is also widely used in energy, aerospace, chemical electronics and other aspects.  

But because of the low toughness and high brittleness of ordinary alumina ceramics, its application field is limited.  In addition, the high sintering temperature is also a major reason for its limited application.  In order to obtain ceramic materials with high hardness and crystallinity, sintering must be carried out at a relatively high sintering temperature, which will inevitably lead to the increase of energy consumption.  

In recent years, because of the higher and higher requirements for material properties, people put forward various methods to improve the performance of alumina ceramics, including hot pressing sintering, discharge plasma sintering, microwave sintering and adding additives.  After adopting some new measures, the flexural strength and hardness of alumina ceramics are greatly improved.  

Nano-aluminum oxide

Since the last century, nanotechnology has developed vigorously, and various nanomaterials have been developed continuously.  Nano science and technology progress has far-reaching influence on the alumina industry, for the widely application of nanometer alumina has brought a new research direction, as a special functional material of nanometer alumina, high hardness, high strength, corrosion resistance, wear resistance, high temperature resistance, high insulation, excellent oxidation resistance and many other features,  Therefore, it is widely used in precision ceramics, bioceramics, chemical catalysts, refractories, integrated circuits, aerospace and other aspects.  

Nano alumina and alumina as the same substance, but different particle size.  Then, in alumina ceramics mixed with a certain amount of nano alumina will have what effect?  

Influence on the properties of aluminum oxide ceramics  

01  The effect on the body  

Adding a certain amount of nano alumina in the preparation of alumina ceramics, in the process of forming, nano powder can be fully filled into the alumina powder gap, reduce porosity, improve the strength of forming body, is conducive to sintering.  

02  Influence on sintering  

1)  Influence on sintering temperature  

Due to the small size and high surface activity of nano-alumina, adding a certain amount of nano-alumina can effectively improve the diffusion rate of billet surface, reduce the sintering temperature, and improve the densification degree of sintering products.  

This is because nano-alumina has a large number of interfaces, providing a short-range diffusion path and a high diffusion rate, and makes the sintering driving force of the material also increase dramatically, greatly speeding up the whole sintering process, so that the sintering temperature is greatly reduced.  

2)  Influence on crystallinity  

When the sintering temperature of alumina ceramics is decreased, the crystallinity does not decrease.  The so-called crystallinity refers to the degree of crystallization of atoms in a regular arrangement of materials in the sintering process, that is, the percentage of the mass or volume of the crystalline part to the mass or volume of the whole, in other words, the proportion of the crystalline area of the product after sintering.  The physical and mechanical properties of materials are different with different crystallinity, and the electrical and optical properties of materials are also affected by the degree of crystallization to a considerable extent.  

03  Influence on mechanical properties  

1) Improve the hardness of alumina ceramics.  

2) Improve the strength of alumina ceramics.  

3) The elastic modulus of alumina ceramics is increased and the toughness is improved.  

In comparison, the physical properties of the pure nanometer alumina ceramics is much more than ordinary alumina ceramics is excellent, but the preparation of nanometer alumina technology is complex, high cost, and alumina ceramic itself has very excellent performance, so in some cases, can be selectively adding nanometer alumina performance boost, ensure the product quality already so,  Improved production efficiency, and reduce production costs.