Physical properties of ferrite magnets
In the actual production of ferrite magnets, the raw materials with good chemical composition may not be able to obtain ferrite magnets with good properties and microstructure. The reason is the influence of physical properties. The physical properties of iron oxide listed include average particle size APS, specific surface area SSA and loose density BD. Since ferric oxide accounts for about 70% in the formula of manganese zinc ferrite magnet, its APS value has a great influence on the APS value of ferrite magnet powder. Generally speaking, the APS value of iron oxide is small, and the APS value of ferrite magnet powder is also small, which is beneficial to speed up the chemical reaction. However, the APS value should not be too small considering that the particle size of powder is not conducive to the subsequent pressing and sintering is easy to crystallize. Obviously, when APS value of iron oxide is too large, the diffusion reaction of spinel phase can only be carried out due to the large particle size during pre-firing, but the grain growth process cannot be further carried out. This will inevitably lead to the increase of activation energy required during sintering, which is not conducive to solid phase reaction.