Hard magnetic ferriteA treasure trove of materials known as permanent magnets, including Ba ferrite, Sr ferrite, Pb ferrite in the form of magnetite, and Co ferrite in the form of spinel. This article will take you on a deep understanding of the production process of hard magnetic ferrite and how to prepare high-quality magnets through additives.
Accurate formula and high-purity raw materials - the first step in the preparation of ferrite
The preparation process of ferrite first requires high purity of raw materials and precise formula composition. High purity raw materials can reduce the impact of impurities on the properties of ferrites, so material selection is particularly important. Common raw materials include iron oxide, iron carbonate, barium oxide, calcium oxide, etc. Among them, the purity of iron oxide is the key to preparing high-quality ferrite.
Balancing grain size and rational orientation - a key step in the preparation of ferrites
The preparation of hard magnetic ferrite requires not only high purity of raw materials and precise formulation composition, but also moderate grain size, uniform distribution, reasonable orientation, and dense structure of the magnet. The size and distribution of magnetic grains determine the quality of their magnetic properties, while orientation refers to the orientation of the main magnetic grains in the magnetic grains, which has a significant impact on the magnetization behavior of the magnet. Therefore, in the preparation process, it is necessary to adjust the grain size and distribution, as well as the formation of orientation, by optimizing process parameters such as pre sintering temperature, sintering temperature, etc.
Sintering Temperature and Oxidation Atmosphere: The Mystery of Temperature in Ferrite Preparation
The pre sintering temperature of hard ferrite is generally between 1100 and 1300 ℃, and the sintering temperature is carried out in an oxidizing atmosphere of 1150 to 1250 ℃. Different types of ferrites have different preparation temperatures and conditions. Taking Ba ferrite as an example, its preparation process involves pre sintering the raw materials at a temperature of 1100-1200 ℃, and sintering at a temperature of 1150-1250 ℃ after forming. Co ferrite, on the other hand, needs to be pre fired at a lower temperature, then fired under reduced pressure at a temperature of 1100 ℃, and subjected to a magnetic field at a Curie temperature of around 300 ℃, and finally slowly cooled to form.
Control sintering density - a densification method for ferrite preparation
The sintering density of ferrite is closely related to the residual magnetic induction intensity, that is, the higher the density, the greater the residual magnetic induction intensity. However, although increasing the sintering temperature can increase the density of the magnet, it can lead to the growth of magnetic phase grains, which has an adverse effect on the magnetic induction intensity. To solve this problem, engineers introduced the concept of additives. By introducing additives, the sintering speed can be accelerated, the density can be increased, and the growth of magnet grains can be effectively suppressed. Common additives include Al2O3, AS2O3, and Bi2O3.
Conclusion:
Advanced Institute of Technology Hard Magnetic FerriteAs an important permanent magnet material, it plays a crucial role in modern technology and industrial fields. Starting from the preparation process, this article introduces key steps such as purity selection, grain control, sintering temperature setting, and density control of hard magnetic ferrite. Only by strictly controlling and optimizing every step can high-performance hard ferrite be prepared. Let us cherish this precious permanent magnet material and contribute to technological progress.
