Refractory metals such as Rhenium, Niobium, Tungsten and Molybdenum are a very soft, and any loose or fracture 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 use the tougher alumina abrasive and to chemically etch the specimen between each grinding step. The purpose of etching is to remove the embedded particles and not carry them over as contamination.
SECTIONING
MAXCUT Abrasive blade (Cat. No. MAX-C or MAX-I series)
MOUNTING
Compression Mounting with Phenolic, Epoxy or Diallyl Phthalate compression mounting resins
POLISHING
Abrasive/surface |
Lubricant |
Force/ sample |
Time |
30 micron alumina film paper |
Water and etchant |
5 lbs |
Until plane |
| 1 um DIAMAT diamond on ATLANTIS polishing pad | DIALUBE Purple Extender |
5 lbs |
1 minute |
0.05 um acidic Nanometer acid alumina on a BLACKCHEM 2 pad |
Polishing with 10% Diluted etchant below: Niobium - 30 ml HCl, 15 ml HNO3, 30 ml HF (40%) Rhenium - 30 ml lactic acid, 30 ml HNO3, 1 ml HF Molybdenum - 15 ml HNO3, 3 ml HF, 80 ml water |
5 lbs |
30 seconds |
 |
Niobium alloy (BF), etched |
 |
Rhenium (BF), etched |