Etching Is a Chemical or Electrolytic Process Used after Metallographic Grinding and Polishing Procedures.
Etching Enhances the Contrast on Surfaces in Order to Visualize the Microstructure or Macrostructure.
Etching in materialography exerts a controlled influence on the surface profile or optical properties at grain boundaries, phases, or grain surfaces, thus enabling microscopic inspection and additional use of optical filters in the microscope. Preparation before the etching process must be adapted to the investigation target.
Scratches and deformation are acceptable for both methods. Depending on the preparation target, however, scratches and deformations can overlay or influence the phase or structur e that should be visible after etching.
Using an incorrect electrolyte or etchant means it will not be possible to verify a surface structure according to the required parameters.
Voltage and Exposure
In the case of electrolytic etching, the voltage and exposure times are critical to revealing t he correct surface structure for a valid verification. Exposure time, and sometimes temperature, are important parameters when using chemical (wet) etching.