Metallographic Preparation Procedures - Glass

Alumino-silicate Glass Ceramic

Glass ceramics are unique materials that have very samll crystalline structures. The primary advantage of glass ceramics is that they produce very interesting thermochemical properties because they are impervious to thermal shock.

Proper microstructural preparation of these materials requires minimizing damage during cutting or sectioning. Therefore, the most important step in the preparation of glass ceramics is sectioning. If the glass ceramic is chipped or excessively cracked during sectioning, it may be impossible to remove this damage. Wafer sectioning with a fine grit diamond wafering blade is essential.

Planar grinding is accomplished with diamond on a metal mesh cloth to minimize cracking and subsurface damage. For rough polishing, the use of a low-napped polishing pad with polycrystalline diamond and colloidal silica eliminates most of the surface and subsurface damage. Final polishing is accomplished with a resilient porous urethane polishing pad such as BLACKCHEM 2 using SIAMAT colloidal silica.

SECTIONING
Diamond Wafering blade - fine grit / low concentration

MOUNTING
Castable Mounting with Epoxy or Acrylic resins

POLISHING

Figure 1. Fine grit diamond cut of glass		Figure 2. Medium grit diamond cut of glass

Alumino-silicate glass ceramic, 400X (Polarized light) as polished