Conductometric determination of microamount of carbon in iron and steel

Abstract

Conductometric determination of microamount (0.5 30 ppm) of carbon in iron and steel was studied. The carbon dioxide produced by heating samples in a purified oxygen current was absorbed in 150 ml of 1.2 × 10^-3N barium hydroxide solution containing 2 g of barium carbonate, and the change of the conductivity (2.042.16 m±Ω) of the solution, kept at 43.6 ± 0.01°C, was measured.
As the standard of carbon, 01.00 ml of sodium oxalate solution (50.2 mg Na₂C₂O₄/l) was placed in a quartz crucible, heated to dryness at 280°C, and decomposed in the furnace to produce carbon dioxide at about 900°C. In order to minimize the blank value, zirconia, beryllia, quartz, and various porcelein crucibles were compared and the porcelein (SiO₂ 90%, Al₂O₃ 7%) crucible was recommended to be adequate for this purpose.