What are the methods for determining the original grain size of alumina ceramics
What are the methods for determining the original grain size of alumina ceramics
Alumina ceramics are calcined at high temperature to obtain alumina ceramics, and the particle size value generally refers to the particle size of the alumina ceramic body. The original crystal particle size and particle size of alumina ceramics are two different terms. In recent years, some colleges and universities and research units have done some research on their own in order to determine the essentials. Of course, there are related reports, but the technical details have not been disclosed. So what are the methods for determining the original grain size of alumina ceramics?
1. Electron Microscopy
The method of combining chemical corrosion and scanning electron microscopy to determine the grain size is intuitive and strong. It is an effective method that can reflect the morphology and size of the crystal grains, but the equipment investment is large and the analysis cost is high.
2. X-ray diffraction method
The most important thing is the spectral line broadening method, which can measure the grain size of pseudo-boehmite, but the diffraction spectrum of a alumina ceramic series products is narrow and sharp, and experiments show that there is no effect; even Because of the influence of mineralizers, the intensity of the diffraction peaks is inconsistent with the JCPDS card, which in turn affects the correctness of the quantitative analysis of α alumina.
3. Nitrogen adsorption ratio nominal method
It is more suitable for porous active materials, but because the a alumina ceramic sintered body obtained from high temperature is dense, there are few open and closed pores, and it is difficult for liquid nitrogen molecules to enter the gaps of crystal grains, so the scope of measurement is limited. , The error in the determination of grain size is also large, and the principle of this method limits its industrial use value.
4. Infrared spectroscopy structure analysis method
Because the size of the spectrum receiving band is related to the size of the grain size, an adsorption band area integrator can be introduced into the structure of the infrared spectrometer to calculate the uniform grain size. The amount of supplies analyzed by this method is very small. For samples with a wide range of grain size dispersion, how to obtain representative samples is still objectively difficult.
5. Grinding method
In the early years when Alcoa's colleagues came to China, they mentioned this method. In a specific volume, with a certain ratio of material to ball and a fixed grinding time, the particle size analyzer was used to measure the grain distribution and median of the crushed material. Diameter D50, and use this method to achieve macro control.
Alumina ceramics, also called alumina ceramics, are made from aluminum hydroxide raw materials or industrial alumina after high-temperature firing. It is widely used in refractory materials, abrasives, ceramics and many other industries.
