Niobium and rhenium is a very soft metal in which abrasive particles can easily embed. This makes specimen preparation very difficlut because it gums up diamond grinding disks or becomes embedded with fractured SiC particles when gound with SiC papers. The key to preparation of this material is to chemically etch the specimen between each SiC grinding step. This way the embedded particles are removed and the subsequent steps are easily performed.
Rough and final polishing are much easier if the embedded silicon carbide particles have been removed by etching.
SECTIONING
MAXCUT Abrasive blade (Cat. No. MAX-D series)
MOUNTING
Compression Mounting with Phenolic, Epoxy or Diallyl Phthalate compression mounting resins
POLISHING
Abrasive/surface |
Lubricant |
Force/ sample |
Time |
320 grit SiC paper |
Water and etchant |
5 lbs |
Until plane |
3 um DIAMAT diamond on DACRON pad |
DIALUBE Purple Extender |
5 lbs |
2 minutes |
| 1 um DIAMAT diamond on DACRON pad | DIALUBE Purple Extender |
5 lbs |
1 minute |
0.05 um acidic Nanometer acid alumina on a BLACKCHEM 2 pad |
10% Diluted etchant Niobium - 30 ml HCl, 15 ml HNO3, 30 ml HF (40%) Rhenium - 30 ml lactic acid, 30 ml HNO3, 1 ml HF |
5 lbs |
30 seconds |
 |
Niobium alloy (BF), etched |