Microscopic Examination
In this experiment, our aim is examining the microstructure of metals. By studying microscopic structures of metals, we determine which material fits best to a given application. We used the most common method, optical technique, to examine the microstructure.We used a small specimen cut from the metal to be examined. To be able to see the structure clearly, we first cleaned and polished the specimen. First we start polishing with emery paper no: 1 and some finer grades. One should be careful about the coa
Mounting not only protects our sample but also by making its base flat and stable helps us while we are examining the sample under the microscope. We filled the die cavity with Bakelite and then we transferred our die to a mounpress. In etching process, depending upon chemical composition, energy content and grain orientation, we determine the grain boundaries and the presence of chemically different phases. We kept polishing until we obtained a mirror like face. After we finished polishing, the crystalline structure of the specimen, any cracks, seams, non-metallic inclusions and inhomogenities, could be revealed. At this stage, the first appearance of microstructure can be observed. Before start etching we first applied mounting process. As soon as a bloom appeared we removed the mount. Finally, we polished the specimen on a rotating cloth covered with an effective abrasive like Al2O3-Water suspension. To reveal these micro structural details of the polished mount we used an etchant like 1% Nital. Cleaning and rotating the specimen 90 during the transfer can prevent these. In this step we used a matched die set. We immersed the mount with the polished face upward in a small dish of etching solution. The next step is polishing, yet washing the sample before polishing gives a more successful result.
Common topics in this essay:
EXAMINATION METALS,
die set,
polished specimen,
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Acceptance Essays
