The metallographic specimen preparation of thermal spray coatings is affected by the specimen composition and deposition conditions. Microstructural features of interest include: porosity, flow, thickness and inclusions. Proper metallurgical preparation takes into account that the microstructure may be porous and perhaps somewhat brittle because of inadequate processing. Following proper cutting to avoid creating undue damage, the specimen is generally mounted in either a castable epoxy or acrylic.
SECTIONING
Not required
MOUNTING
Castable mounting acrylics or epoxies
POLISHING
Abrasive/surface |
Lubricant |
Force/ sample |
Speed |
Time |
30 um DIAMAT diamond on CERMESH metal mesh cloth |
DIALUBE Extender |
5-10 lbs |
100/100 rpm |
Until plane |
9 um DIAMAT diamond on SIRIUS composite disk |
|
5-10 lbs |
100/100 rpm |
3 minutes |
3 um DIAMAT diamond on ORION composite disk |
|
5-10 lbs |
100/100 rpm |
3 minutes |
1 um DIAMAT diamond on ATLANTIS polishing pad |
DIALUBE Purple Extender |
5-10 lbs |
100/100 rpm |
2 minutes |
| 0.05 um NANOMETER Alumina on TRICOTE polishing pad | 5-10 lbs | 100/100 rpm |
1 minute |
 |
Nickel Chrome Thermal Spray Coating, as polished |