高張力鋼中のバナジウムの態別定量

Abstract

A simple and accurate method has been developed for the metallographic analysis of vanadium in high strength steel.1. Separation of vanadium compound from steel.(a) The steel sample covered with close-texture filter paper as a diaphragm and connected as an anode, is dissolved into 100 to 130ml of 1% NaCl-5% EDTA electrolyte (pH 6-7) with current density of 50 mA/cm2 for 1 to 2 hr. Remove the anode, and residue is collected into the filter paper. To the residue and filter paper add 50ml of HCl (1: 4), and pass in a stream of air for 30 min at room temperature.(b) Filter and wash with water. Add 5ml of HNO3 and 10ml of HClO4 to the filterate and evaporate to dense white fumes, cool, dilute to 50ml and determine vanadium as (Fe, V) 3C in accordance with section 2.(c) Add 30ml of HNO3 and 20ml of HClO4 to the electroyte and evaporate to dense white fumes, cool, dilute to 100ml, and determine vanadium as solid solution in accordance with section 2.(d) Transfer the paper and residue (paragraph (b)) to a beaker, add 30ml of HCl (1:1) and boil for 5 min.(e) Filter and wash with water. Add 5ml of HNO3 and 10ml of HClO4 to the filterate and evaporate to dense white fumes, cool, dilute to 50ml, and determine vanadium as V2O3 in accordance with section 2.(f) Transfer the paper and residue (paragraph (e)) to a beaker, add 40ml of HNO3 (1:3), and boil for 5 min.(g) Filter and wash with water. Add 10ml of HClO4 to the filterate and evaporate to dense white fumes, cool, dilute to 50ml, and determine vanadium as V4C3 in accordance with section 2.(h) Transfer the paper and residue (paragraph (g)) to a beaker, add 30ml of HNO3 (1:1) and 5ml of H2O2 and boil for 10 min.(i) Filter and wash with water. Add 10ml of HClO4 to the filterate and evaporate to dense white fumes, cool, dilute to 50ml, and determine vanadium as VN in accordance with section 2. Discard the residue.2. Photometric determination of vanadium.Transfer 20ml of each of solutions (section 1.(b), (c), (e), (g) and (i)) to separatory funnels, add 2ml of copper solution (0.5%) and 1 drop of KMnO4 solution (1%), and let stand for 5min. Add 15ml of N-benzoylphenylhydroyxylamine chloroform solution (0.067%) and 10ml of HCl (2:1), and shake for 30 sec. Measure the absorbance of organic phase against chloroform at 530mμ.