GB/T 4324.12-2012Methods for chemical analysis of tungsten - Part 12: Determination of silicon content - Chlorization-molybdenum blue spectrophotometry (English PDF)

3.1

hydrofluoric acid by azeotropic distillation purification or superior grade pure purity above.

3.2

nitric acid (rho = 1.42g/mL), pure class distinctions.

3.3

potassium chloride solution (10g/L).

3.4 boric acid solution (60g/L)

Weigh 60g excellent pure boric acid, heated and dissolved in water and diluted to 1000mL, and mix. when necessary filter.

3.5

potassium permanganate solution (10g/L), with the preparation.

3.6 ammonium molybdate solution (100g/L)

Weigh 50g excellent pure ammonium molybdate, heated and dissolved in water and diluted to 500mL, and mix. when necessary

Filtered and stored in a plastic bottle.

3.7 oxalic acid - sulfuric acid mixed solution

Weigh 30g of oxalic acid in 1000mL beaker, 200mL of water, sulfuric acid was slowly added 300mL (11) were stirred and dissolved, and diluted with water to 1000mL, mixing, stored in a plastic bottle.

3.8 Silicon reductant

Weigh 5g of anhydrous sodium sulfite and 0.050g1- amino-2-naphthol-4-sulfonic acid dissolved in water and diluted to 50mL, mix

Mix to dissolve, formulated with time.

3.9 silicon standard stock solution

Weigh 0.1069g pre-calcined at 900 °C silica (wSiO2>=99.99%) in a platinum crucible,

Add 4g of anhydrous sodium carbonate and placed 900 °C ~ 950 °C high temperature furnace to melt red transparent (about 12min). Remove the cooling water washed crucible

Crucible bottom, extraction with boiling water in a plastic cup frit, wash the platinum crucible and cooled. Transferred to 500mL volumetric flask, dilute to the mark, mix,

Store in plastic bottle. This solution 1mL containing 100µg silicon.

3.10 Silicon standard solution

Pipette 25.00mL silicon standard stock solution (3.9) in 500mL flask, add 1g of anhydrous sodium carbonate, shake

Move to dissolve, dilute with water to volume, and mix, stored in a plastic bottle. This solution 1mL containing 5µg silicon.