Sample preparation process steps:
1. Sampling:
--- The size of the sample is to be easy to hold and easy to grind. Usually, the cylinder of Φ15mm×15～20mm has a length of 15-25mm. Specimens that are special in shape or small in size and difficult to hold are to be inlaid or mechanically clamped.
For details, please refer to "Metal Phase Sample Sampling Method"
2. Mounting:
---Separate cold inlay and hot inlay, the inlay material is bakelite powder, electric jade powder and so on. The bakelite powder is opaque, has various colors, is relatively hard, and the sample is not easy to chamfer, but the corrosion resistance is relatively poor; the electric jade powder is translucent or transparent, and has good corrosion resistance, but is soft. Mounting with both materials requires a special inserter to heat up to form.
Materials that are extremely sensitive to temperature and pressure (such as quenched martensite and soft metals susceptible to plastic deformation) and microcracked samples should be cold-set and washed to cure at room temperature. Will cause changes in the tissue of the sample. Epoxy resin and dental powder mosaic method are particularly suitable for powder metal and ceramic porous samples.
For details, please refer to "metallographic sample mosaic method"
3. Polishing:
--- Rough grinding: Leveling the sample and grinding it into a suitable shape, usually on a grinder.
--- Fine grinding: often carried out on sandpaper. Sandpaper water sandpaper and metallographic sandpaper. Generally, water sandpaper is SiC abrasive insoluble in water. Metallographic sandpaper abrasives are artificial corundum, silicon carbide, iron oxide, etc. It is extremely hard, has polygonal edges and has good cutting performance. It can be used as a lubricant for manual grinding after grinding. Or mechanical wet grinding, usually after polishing with five kinds of water sandpaper with particle size of 240, 320, 400, 500, 600, after polishing, for softer metal, use finer metallographic sandpaper to polish and then polish.
4. Polishing:
--- Make the micro-wear marks left by the polishing become a bright and non-marking mirror.
--- Rough polishing: Remove the polished deformed layer. The commonly used abrasive is α-Al2O3, Cr2O3 or Fe2O3 with a particle size of 10-20 μm, and is added with water to form a suspension. At present, synthetic diamond abrasives have gradually replaced abrasives such as alumina.
---- Fine polishing (also known as final polishing): remove the deformation layer produced by rough polishing to minimize polishing damage. Operators are required to have higher skills.
Matters needing attention: In the process of grinding and polishing, according to the different materials, choose the appropriate addition materials, so as not to cause improper use of auxiliary materials to produce chemical reactions on the materials, such as aluminum can not use alumina polishing powder, otherwise it will produce chemical reactions, causing materials Changes in organizational structure, which affect test data and results.
5. Chemical corrosion of metallographic samples
---- Rinse the polished sample with water or wipe off the residual dirt on the surface with alcohol, then immerse the sample surface in the corrosive agent, or use a bamboo clip or wooden clamp to clamp the cotton ball to get the corrosive agent. Wipe the surface of the sample, and the polished surface will gradually lose its luster. Immediately after the sample is corroded, rinse it off with water, blot it with filter paper or blow dry the sample with a hair dryer, and then observe it under the microscope. Corrosion is slightly shallower when observed at high magnification, while corrosion is deeper at low magnification.
1. Sampling:
--- The size of the sample is to be easy to hold and easy to grind. Usually, the cylinder of Φ15mm×15～20mm has a length of 15-25mm. Specimens that are special in shape or small in size and difficult to hold are to be inlaid or mechanically clamped.
For details, please refer to "Metal Phase Sample Sampling Method"
2. Mounting:
---Separate cold inlay and hot inlay, the inlay material is bakelite powder, electric jade powder and so on. The bakelite powder is opaque, has various colors, is relatively hard, and the sample is not easy to chamfer, but the corrosion resistance is relatively poor; the electric jade powder is translucent or transparent, and has good corrosion resistance, but is soft. Mounting with both materials requires a special inserter to heat up to form.
Materials that are extremely sensitive to temperature and pressure (such as quenched martensite and soft metals susceptible to plastic deformation) and microcracked samples should be cold-set and washed to cure at room temperature. Will cause changes in the tissue of the sample. Epoxy resin and dental powder mosaic method are particularly suitable for powder metal and ceramic porous samples.
For details, please refer to "metallographic sample mosaic method"
3. Polishing:
--- Rough grinding: Leveling the sample and grinding it into a suitable shape, usually on a grinder.
--- Fine grinding: often carried out on sandpaper. Sandpaper water sandpaper and metallographic sandpaper. Generally, water sandpaper is SiC abrasive insoluble in water. Metallographic sandpaper abrasives are artificial corundum, silicon carbide, iron oxide, etc. It is extremely hard, has polygonal edges and has good cutting performance. It can be used as a lubricant for manual grinding after grinding. Or mechanical wet grinding, usually after polishing with five kinds of water sandpaper with particle size of 240, 320, 400, 500, 600, after polishing, for softer metal, use finer metallographic sandpaper to polish and then polish.
4. Polishing:
--- Make the micro-wear marks left by the polishing become a bright and non-marking mirror.
--- Rough polishing: Remove the polished deformed layer. The commonly used abrasive is α-Al2O3, Cr2O3 or Fe2O3 with a particle size of 10-20 μm, and is added with water to form a suspension. At present, synthetic diamond abrasives have gradually replaced abrasives such as alumina.
---- Fine polishing (also known as final polishing): remove the deformation layer produced by rough polishing to minimize polishing damage. Operators are required to have higher skills.
Matters needing attention: In the process of grinding and polishing, according to the different materials, choose the appropriate addition materials, so as not to cause improper use of auxiliary materials to produce chemical reactions on the materials, such as aluminum can not use alumina polishing powder, otherwise it will produce chemical reactions, causing materials Changes in organizational structure, which affect test data and results.
5. Chemical corrosion of metallographic samples
---- Rinse the polished sample with water or wipe off the residual dirt on the surface with alcohol, then immerse the sample surface in the corrosive agent, or use a bamboo clip or wooden clamp to clamp the cotton ball to get the corrosive agent. Wipe the surface of the sample, and the polished surface will gradually lose its luster. Immediately after the sample is corroded, rinse it off with water, blot it with filter paper or blow dry the sample with a hair dryer, and then observe it under the microscope. Corrosion is slightly shallower when observed at high magnification, while corrosion is deeper at low magnification.
More metallographic cutting machine consultation:
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