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Mechanical Grinding and Polishing

A fine mechanical (or chemical) polish is required for specimens that will be analyzed using optical microscopy or certain SEM techniques (EDS elemental analysis and EBSD phase and orientation characterization in particular). Flat surfaces are also needed for accurate results XRD of solids and GDS.

Mechanical grinding and polishing consists of removing material from a specimen with increasingly fine grit grinding paper or polishing compounds (typically performed on a rotating wheel platen). Common practice is to hold a specimen at one orientation per grinding/polishing step to keep scratches in a uniform direction. Between steps, the sample is rotated 90º so that it is apparent when all scratches from the previous step are removed. Failure to remove large scratches from early steps will likely result in a poorly polished specimen.

Over-polishing can also damage a specimen, particularly for soft materials, or if there is a large hardness difference between phases present in a material. Consult polishing guides (made available by consumables companies) for a guide on polishing your material.

Clean, uncontaminated grinding paper and polishing pads are crucial to good specimen preparation. Keep your workspace clean for you and your fellow researchers.

Determining ideal polishing time, pressure applied to the sample, platen rotation speed, and other important considerations are up to the researcher to determine for their specimen. Pay attention and take notes; a careful, quality polish and a rushed, poor polish is often the difference between good data and poor data.

Grinding and polishing consumables are included with the lab key fee and provided by the department. Lab staff works hard to ensure that the labs are fully stocked at all times; however, if you notice the lab is running low on a consumable, notify a lab administrator. Note: excessive use of consumables like diamond polishing pastes wastes lab supplies and makes it more likely for the facility to run out of necessary items. Conscientious use of lab materials is part of proper lab use.

Safety Requirements for Entry into the Polishing Lab (2132)

Safety Training Level 3: Click this link for more information.

Electronic Submission of the Hazardous Materials Pickup Request Form to MSE-lab-admin@ecn.purdue.edu.

From the Laboratory Safety page:

  • Go to the REM link for "Waste Disposal including pickup procedures"
  • Click on the Pickup Procedures
  • Read the instructions and fill out the Hazardous Materials Pickup Request Form
  • Click on the PDF Submission option
  • Save the PDF as a separate document, fill it out, and email it as an attachment to to MSE-lab-admin@ecn.purdue.edu (PHYSICAL COPIES WILL NOT BE ACCEPTED)
  • Note: Fill out the room the waste is located in. The department code is NOT NECESSARY
  • If you have questions, call REM at 765-494-6371

Equipment

Grinding Belts

Grinding Wheels

Polishing Wheels

Pace GIGA900 Vibratory Polisher