1. Turn on the oxygen meter and adjust it to 0.02 ~ 0.04 MPa.
2. Take down the crucible, first add silicon molybdenum powder + sample + tin particles (Note: silicon molybdenum powder, tin particles about 0.3g).
3. Turn on the "front oxygen" and "rear control" switches, and adjust the flowmeter to about 100.
4. Click "start arc", add "carbon" to make light blue, and then drop "sulfur" to green.
Chemical reagent preparation
Prepare the required reagents:
(1) Sulfuric acid (1:85): 1 part sulfuric acid + 85 parts water;
(2) Mixed indicator: weigh 0.4g methyl red and 0.4g bromocresol green respectively, dissolve them in 250 ml alcohol and mix them;
(3) Sodium hydroxide (1n): weigh 4G sodium hydroxide + 100ml water (4%).
(4) Thyme phenolphthalein (0.5% ethanol): weigh 0.5g thyme phenolphthalein + 100ml absolute ethanol;
(5) Potassium hydroxide: (50%): weigh 50g potassium hydroxide + water to 100ml.
Carbon reagent:
Potassium hydroxide (50%) 5ml + 500ml anhydrous ethanol + 30ml ammonium alcohol + 10ml thyme phenolphthalein solution + anhydrous ethanol to 1000ml (Note: add 15ml potassium hydroxide to measure iron and 5ml to measure steel).
Sulfur reagent:
(1) Glass bottle: 1 L water + 20 ml hydrogen peroxide + 20 ml mixed indicator + 2 drops of sulfuric acid (1:85) + water to 2 L (light red).
(2) Plastic bottle: 3 ml sodium hydroxide solution (1V) + 1 L water.