Dear Rakibul Hassan,

I am not expert on sintering process.

But , I think , several times sintering at same temperature and following the same time profile will not give any new change of the electric and magnetic properties of the material.

Thanks

N Das

Typically, ceramic technology uses double sintering: pre-sintering, in which the solid-phase reaction of the components occurs, and most of the raw materials are converted to the ferrite phase. The pre-sintered billet is then ground into a fine powder, pressed, and subjected to second sintering, which finally forms the properties of the ferrite material.

The properties of ferrites are very sensitive to changes in the parameters of the microstructure (porosity, grain size, the nature of their boundaries, etc.), which is largely determined by the technology of their manufacture. So, for example, to increase the coercive force, it is necessary to have small (single-domain) grains. In this case, the processes of magnetization and demagnetization by moving the domain walls will be difficult. Therefore, such factors as the parameters of ferrite sintering and the use of special impurities that provide the required values of the coercive force and residual induction are important. The introduced fine component, at the second stage (during grinding), effectively inhibits the growth of grains, contributing to the production of dense, homogeneous, fine-grained ferrite materials.

If all the chemical reactions and diffusion processes during sintering have been completed, the repeated processing cycle should not lead to any significant changes in the characteristics of the sample.

Thank you sir (@N Das) for your valuable reply.

As pointed out by A T Morchennko, the idea of presintering is to achieve partial chemical reaction. Generally the ingredients are loosely packed in the form of a cake but not loose powder. This is to ensure the particles to bring to bring closer which allows the chemical reaction to take place. In the final sinertering complete reaction will be over. After that even if the process is repeated no significant changes in the physical properties can be noticed. But if one doors with glass forming agents they will change the properties.

if you sintered your material for the same temperature , you will not see any tangible in its electrical and magnetic properties

Thank you sir (Kota Venkata Sivakumar) for your helpful comment.

Thank you sir (Nadir Fadhil Habubi) for your helpful comment.

Thank you sir (Nityananda Das) for your helpful comment.