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	Speed (Head/base)	Time	Individual Force mode	Central Force mode
P120 grit ALO paper* P220 grit ALO paper*	Water	5-10 lbs	100/100 rpm	Until plane 1 minute
P500 grit ALO paper P1200 grit ALO paper	Water	5-10 lbs	100/100 rpm	1 minute 1 minute
1 um DIAMAT diamond on ATLANTIS polishing pad	DIALUBE Purple Extender	5-10 lbs	100/100 rpm	2 minutes
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%)	5-10 lbs	100/100 rpm	1 minute

*Required for central polishing force. Click here for more information on central vs. individual polishing force polishing.

Niobium alloy (BF), etched

ETCHING

Common Etchants

CAUTION:Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacuters SDS (Safety Data Sheets). Also review the COMMENTS and CONDITIONS Section for each etchant.

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