As friends know, the final process of preparing metallographic samples is to use polishing solution for fine polishing. The purpose of using polishing solution is to remove the surface deformation layer of the sample that is not visible to the naked eye. Especially when using high-power objective lenses, polarized light, differential interference contrast to evaluate samples, or when using EBSD technology, it is essential to remove this deformation layer on the surface of the sample.
At present, the commonly used polishing fluids are basically divided into two categories, namely alumina polishing fluid and silicon oxide polishing fluid, both of which belong to suspension. There are differences in the application of these two types of polishing fluids, and friends in the metallographic industry must understand them in order to choose and use them correctly in practical applications.
Aluminum oxide polishing solution contains sol-gel aluminum oxide, which can efficiently remove materials through pure mechanical polishing, achieving excellent surface treatment effects. Non crystalline silica gel polishing solution, which has weak alkalinity, forms a reaction layer with the material surface through chemical mechanical polishing methods. Soft silica gel can remove the reaction layer to obtain a high-quality surface. Therefore, different types of metallographic polishing fluids use different polishing mechanisms. The different types of materials determine whether to choose alumina polishing solution or silicon oxide polishing solution.

Scope of application of alumina polishing solution:
Non agglomerating alumina polishing solution with a pH value of 8.5 is suitable for the preparation of material samples that use pure mechanical methods to remove surface deformation layers and scratches, including steel, stainless steel, cast iron, copper, precious metals, polymers, minerals, microelectronics, etc.
Scope of application of silicon oxide polishing fluid:
Amorphous silicon oxide polishing solution with a pH value of 10.5 can achieve excellent scratch free surface effect, suitable for the preparation of material samples that generate reaction layers through chemical reactions and then remove the reaction layers through mechanical means. It includes: ceramics, aluminum, Refractory metals, silicon in microelectronics, etc.
In the following examples of brazing layers, alumina polishing solution and silicon oxide polishing solution are suitable for different analyses.

From the comparison of the above two figures, it can be seen that pure mechanical polishing with aluminum oxide polishing solution can make the sample surface flat, but it cannot guarantee that copper will not occur. Therefore, aluminum oxide polishing solution is more suitable for coating measurement and Boundary layer analysis. Using silicon oxide polishing solution, chemical mechanical polishing can cause corrosion on the solder and slight polishing protrusion, but it will not damage the sample. Therefore, silicon oxide polishing solution is more suitable for microstructure analysis and EBSD of copper.
Through the above explanation and case analysis, I believe that friends have a clear understanding of the practical applications of aluminum oxide polishing fluid and silicon oxide polishing fluid. It is my wish to provide you with work assistance. If friends have any further questions that need to be resolved, please feel free to contact us.