抄録
This work, a part of a general investigation on the state analysis of steel, was carried out to develope a systematic method for isolation and detemination of chromium compounds in low alloy steel.
1. Isolation of chromium compounds from steel.
(a) The steel sample covered with close-texture filter paper as a diaphragm, connected as an anode, is dissolved into 120ml of 1% NaCl-5% EDTA electrolyte (pH 6-7) with a current density of 50mA/cm2 for 1hr. Remove the anode, and the residue is collected into a beaker by making use of methanol.
(b) To the residue and 50 ml of 2% EDTA solution (pH 5-6), and shake for 1 hr. Filter and wash with 0.01M. EDTA solution. Determine the chromium in cementite from filterate in accordance with section 2.
(c) Transfer a part of the elestrolyte to a beaker and determine chromium as solid solution in accordance with section 2.
(d) Transfer the paper and residue (paragraph b) to a beaker, add 50ml of HNO3 (1 to 2) and boil for 10min. Filter and wash with water and determine the chromium as Cr7C3 from the filtrate in accordance with section 2.
(e) Transfer the paper and residue (paragraph d) to a beaker, add 50 ml of HCl (1 to 1) and boil for 10 min. Filter and wash with water and determine the chromium as CrN from the filterate in accordance with section 2.
(f) Determine the chromium as oxides from the residue (paragraph e) in accordance with section 2.2. Determination of chromium.
Add 10 to 30ml of HNO3, 5ml of iron solution (0.01g Fe/ml)(expel electrolyte) and 10ml of acid mixture (H2SO44, H3PO43 and H2O8) to each filterate and residue (section 1. b, c, d, e, and f).
Evaporate to white fumes and then determine chromium with usual colorimetric method by diphenyl carbazide.
