Just like grinding, the materialographic polishing process using metallographic polishing agents is based on material removal by machining. However, polishing is performed using much finer grit sizes, assuring considerably lower material removal rates than with grinding.
In brief, two processes can be distinguished in polishing: pre-polishing and final polishing. Polishing with specific metallographic abrasives involves one or several steps in which remaining sample deformations are gradually considerably reduced until scratches are no longer visible on a microscopic scale. Exclusively loose abrasive grains applied to a polishing cloth are used during this process. At the end of the polishing process, the material sample has a polished surface suitable for chemical etching as well as for subsequent microstructure evaluations.
SCAN-DIA offers a comprehensive range of products to help you achieving such precise sample surfaces. Our metallographic polishing materials are exclusively manufactured from high quality constituents.
Diamond has the edge on aluminium oxide Al2O3 when it comes to hardness, sharpness, and cutting ability, making it the most frequently used polishing agent. During the materialographic polishing process, diamond is used in diamond pastes or diamond suspensions. Aluminium oxide Al2O3 (alumina) is only rarely used these days. It can be applied for softer materials during the final polishing step with a grit 1 – 0.25 ?. Silicon dioxide, SiO2, in colloidal suspension may also be used as extra-fine polishing agent.
During the sample preparation process, not only polishing agents but also appropriate polishing pads and lubricants are required. Special cloths made of synthetic fibres, felt, flock, or wool can be used as polishing pads. They are selected according to the requirements. Lubricants (Extender) are added during the polishing process for cooling and lubrication. They are applied in small amounts to obtain an optimum moisture content on the polishing cloth.
In order to ensure optimal preparation results, it is recommended to apply perfectly matched metallographic polishing materials, polishing cloths, and lubricants, such as those available in SCAN-DIA's diamond polishing system.
For more information, see the SCAN-DIA special brochure "Polishing System".
Product catalogue EN 3.20 MProduct catalogue
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