Glass Beads for XRF Analysis of Cement

Tools and Materials

• xrFuse crucibles in Pt95/Au5 (DC1@ 30 g)
• An xrFuse2 (electrical fusion machine)
• An analytical balance with a precision of 0.1 mg and a weighing range of about 200 g
• xrFuse moulds in Pt95/Au5 (AM7@ 100 g – bead = Ø39/41 mm x 4 mm)
• A weighing spatula to weigh the sample
• A spoon-spatula to weigh the oxidizer and flux
• A weighing pan or other
• A furnace for calcination of the sample before fusion (950 °C)
• A vortex mixer to mix the flux and sample together
• A long pair of tongs (20 cm) with plastic tips (to avoid scratching the mould and the crucible)
• An ultrasonic cleaner (with heating) to clean the platinum labware

Note: 95% Platinum 5% Gold (Pt/Au): Universally accepted material of choice for casting and crucible moulds for spectrographic analysis by x-ray fluorescence (XRF).
Note: Never touch the casting surface with tongs: any scratches will transfer to the glass bead measurement surface.

The Chemicals

• Citric acid (a 20% solution to clean the moulds and the crucibles)
• The flux:
  • FLUX LT66/LM34: Lithium tetraborate 66%, Lithium metaborate 34% - (T_m 875 °C)

Calcination

All samples were calcined at 950 °C  for 2 hours before the fusion and the production of the beads.

Preparations of Casting Powders for Fusion

1.000 g +/-0.015 g of sample and 8.000 g of flux FLUX LT66/LM34 should be directly weighed into a fusion crucible and mixed together. In order to ensure that the contact between flux and sample is optimized, the mixture should be thoroughly mixed (about 0.5 minute).

• The crucible containing the powder should be placed into the crucible cradle of the xrFuse2
• The mould should be placed on the mould holder of the xrFuse2
• The desired program should be loaded and the start button be pressed
• The bead should be removed from the mould, once the fusion is complete

Note: Never touch the measurement side with your fingers (the side that faced the casting dish surface).

Fusion Program Settings

Program

This information has been sourced, reviewed and adapted from materials provided by XRF Scientific.

For more information on this source, please visit XRF Scientific.