Ultra-fine alumina powder is an indispensable important material in modern industry. After ultra-fine micronization of alumina powder, its surface electronic structure and crystal structure have changed, resulting in surface effects and small size that macro objects do not have. Effect, quantum effect and macro-quantum tunnel effect, and has excellent characteristics such as high strength, high hardness, wear resistance, corrosion resistance, high temperature resistance, oxidation resistance, good insulation and large surface area. At present, it has been used in bioceramics, precision ceramics, Chemical catalysts, rare earth trichromatic phosphors, integrated circuit chips, and aviation light source devices have been widely used.
1. Ceramic materials and composite materials
Adding ultrafine alumina powder to conventional ceramics can improve the toughness of ceramics and reduce the sintering temperature. Due to the superplasticity of ultrafine alumina powder, it solves the shortage of low-temperature plastics and limits its application range, so it is obtained in low-temperature plastic ceramic Has been widely used.
The use of ultra-fine alumina powder can also synthesize new composite ceramic materials with special functions and aluminum alloy ultra-fine composite materials. Among them, the SiC-Al2O3 ultrafine composite material is the most significant. Its flexural strength is increased from 300-400MPa to 1GPa for single-phase silicon carbide ceramics, and the fracture toughness of the material is also improved by more than 40%.
Ultra-fine alumina can also be used as a dispersion reinforcement and additive. For example, when the cast iron research tool is cast with ultra-fine alumina powder as a modified nucleus, the wear resistance can be increased by more than several times.
2. Surface protective layer material
New ultra-thin transparent material composed of ultra-fine alumina particles, sprayed on the surface of metal, ceramics, plastics and cemented carbide, can improve the surface hardness, corrosion resistance and wear resistance, and has anti-fouling, anti-fouling Dust, waterproof and other functions can solve the problems of easily wearing parts and corrosion pipes in modern industrial production that indirectly affect the service life of equipment and the accuracy of processed products. Therefore, it can be applied to the surface protection of machinery, cutters, chemical pipelines, etc.
Among them, the ultra-fine alumina ceramic coated tools combine the advantages of ceramic materials and cemented carbide materials. While having the strength and toughness similar to the cemented carbide materials, the wear resistance is greatly improved, which can reach several uncoated tools. Times to dozens of times, and the processing efficiency is significantly improved.
3. Catalyst and its carrier
Ultrafine alumina has a good pore size distribution, high pore volume, and a surface area of ​​up to 60-400m2 / g. Incomplete atomic coordination on the surface leads to a lot of mismatched bonds and under-oxygen bonds on the surface. As the particle size decreases, the surface smooth It becomes worse, forming uneven atomic steps and increasing the contact surface of chemical reaction. It is an ideal catalyst or catalyst carrier. The HDS activity of Co-Mo catalyst supported by ultrafine alumina particles is higher than that of Co-Mo supported by ordinary alumina The HDS activity of the catalyst.
The main application of the catalyst and carrier is γ-Al2O3, which is widely used in automobile exhaust purification, catalytic combustion, hydrodesulfurization, petroleum refining, polymer synthesis, etc.
4. Biological and medical materials
The ultra-fine alumina bioceramic basically does not corrode in the physiological environment, has good structural compatibility, the new tissue grows into the interpenetrating pores on the surface of the porous ceramic, and the bonding strength between the body tissue is high, and It has the characteristics of high strength, small friction coefficient and low wear rate. Therefore, it is widely used clinically. It has been used to make bearing artificial bones, joint restorations, root implants, bone splints and internal fixation devices. It has also successfully carried out alveolar ridge expansion and reconstruction of maxillofacial bone defects. , Orthodontics and repair of facial features.
At present, we are focusing on researching soft tissue materials such as artificial trachea and bioceramic materials that simulate biological body functions and artificial intelligence.
5. Semiconductor materials
Ultrafine alumina powder has a very large surface area and interface, and is very sensitive to the external environment moisture. Changes in environmental temperature quickly cause changes in surface or interface ion valence and electron transport. In the range of 30-80% humidity, the AC impedance of ultra-fine alumina changes linearly, with fast response, high reliability, high sensitivity, long anti-aging life, resistance to erosion and pollution by other gases, and can be maintained in dust and smoke environment The detection accuracy is ideal for moisture-sensitive sensors and hygroelectric thermometer materials.
In addition, ultra-fine alumina is a commonly used substrate material, with good electrical insulation, chemical durability, heat resistance, strong radiation resistance, high dielectric constant, uniform surface, low cost, etc. It can be used in semiconductors The substrate materials of devices and large-scale integrated circuits are widely used in the microelectronics, electronics and information industries.
6. Optical materials
Nano-scale alumina can absorb ultraviolet light, and under the excitation of certain wavelengths of light, it can produce light waves with wavelengths related to particle size. It can be used as a protective coating film for the phosphor layer in a compact fluorescent lamp, and can also be combined with rare earth phosphor to make a luminescent material for a fluorescent lamp tube to increase the life of the lamp tube.
Ultra-fine alumina is also an excellent ultraviolet absorber. Adding ultra-fine γ-Al2O3 powder to compact fluorescent lamps can reduce the light attenuation of the lamp and improve the qualification rate of the lamp.
A layer of high-polymer harmless to the surface of alumina particles can also be added to sunscreen and cosmetics.
It is precisely because ultra-fine alumina powder has a series of excellent electrical, magnetic, optical, mechanical and chemical macro-characteristics compared with conventional particles, so in recent years, the preparation of high-purity ultra-fine alumina powder has been the main focus of research in the field of new materials One of the directions.
Trunnano is one of the world's largest producers of nano aluminum oxide powder. Provide nanometer materials such as nanometer aluminum powder and aluminum oxide powder with various particle sizes to the market. If there is a demand, please contact Dr. Leo, email: brad@ihpa.Net.
