Application Fields of Spherical Alumina Powder
The unique physical and chemical properties of ultrafine spherical alumina make it widely used in bioceramics, surface protective layer materials, chemical catalysts and catalyst carriers, integrated circuit chips, aerospace, infrared absorption materials, and moisture-sensitive sensors.
The excellent performance of ultrafine spherical alumina products in many fields is closely related to the morphology and size of the raw powder particles. Regular morphology, small specific surface area, large packing density, good flow performance, high hardness and strength can greatly improve the application performance of the product.
Application fields of spherical alumina powder
1. Precision polishing abrasives
Alumina has gradually been widely used in industries such as precision processing and manufacturing due to its high hardness and good stability, especially in chemical mechanical polishing (CMP).
2.Special ceramic raw materials
The requirements for ceramic bodies are high density, small shrinkage deformation, and easy sintering. The size, morphology and dispersion of ceramic powder are important indicators to measure the performance of the powder. Among the many morphologies of powder, dispersed spherical micro-powder is better.
3. Other applications
Spherical alumina powder can be used as a support for porous alumina. Since the pores formed are relatively regular, it is easy to homogenize the entire support. Alumina powder for filling requires good fluidity, strong ability to combine with organic matter, and a spherical shape is preferred. Alumina is also the main raw material for three primary colors and long afterglow phosphors. In addition, it also has many applications in the fields of catalysts and catalyst carriers.
Preparation of ultrafine spherical alumina
With the rapid development of global industry, spherical alumina powder has been extensively studied in the past 10 years. The preparation of spherical alumina has become a hot topic in materials research.
Ball milling method
The ball milling method is the most common method for preparing ultrafine alumina powder. The rotation or vibration of the ball mill is usually used. The raw materials are impacted, ground and stirred by the abrasive, and the large particle size powder is refined into ultrafine powder.
Homogeneous precipitation method
The precipitation process in a homogeneous solution is a process in which crystal nuclei form, then aggregate and grow, and finally precipitate from the solution. If the concentration of the precipitant in the homogeneous solution can be reduced, or even generated slowly, it will be uniform. A large number of tiny crystal nuclei are generated, and the eventually formed fine precipitation particles will be evenly dispersed throughout the solution and will maintain an equilibrium state for a long time. This method of obtaining precipitation is called homogeneous precipitation.
Sol-emulsion-gel method
In order to obtain spherical powder particles, people use the interfacial tension between the oil phase and the water phase to create tiny spherical droplets, so that the formation and gelation of sol particles are limited to tiny droplets, and finally a spherical precipitation is obtained. Particles.
Drop ball method
The drop ball method is to drop alumina sol into an oil layer (usually paraffin, mineral oil, etc.), and form spherical sol particles by surface tension. Then the sol particles are gelled in an ammonia solution, and finally the gel particles are A method of drying and calcining to form spherical alumina.
Other methods
Spraying method: The essence of preparing spherical alumina by spraying method is to achieve phase transformation in a short time, and use the effect of surface tension to spherical the product. According to the characteristics of phase transformation, it can be divided into spray pyrolysis method and spray drying method. and injection melting.
Aerosol decomposition method: usually aluminum alkoxide is used as the raw material, and the aluminum alkoxide is easily hydrolyzed and pyrolyzed at high temperature, and the physical method of phase change is used to vaporize the aluminum alkoxide, and then contact with water vapor to hydrolyze and atomize , and then dried at high temperature or directly pyrolyzed at high temperature to achieve gas-liquid-solid or gas-solid phase transformation, and finally form spherical alumina powder.
Ultrafine spherical alumina powder has high added value and can bring greater social and economic benefits. In recent years, its demand has continued to grow. Therefore, the spheroidization of ultrafine alumina particles can greatly improve the application performance of its products and has great economic benefits. It is believed that the spheroidized alumina powder market will further expand!