Phase Analysis of Zirconium in Steel

Abstract

In order to establish a method for phase analysis of zirconium in steel, an investigation was made on the chemical behavior of various zirconium compounds in steel. The results obtained are as follows:
1) Fine ZrC and Zr sulfide particles are not quantitatively extracted by mineral acids treatment.
2) Zirconium compounds in steel are quantitatively extracted by the potentiostatic electrolysis methods.
3) The procedure for phase analysis of zirconium in steel is as follows:
a) For isolation of all zirconium compounds in steel, the potentiostatic electrolysis method (30% citric acid-15% sodium citrate-1.2% KBr or 10% acetyl acetone-1% tetramethyl ammonium chloride-methanol electrolyte) is applied and the extracted residue is filtered. (Separation of metallic Zr).
b) The extracted residue is treated by 100 ml of 10% I₂-CH₃OH at room temperature for 20 min and filtered (Separation of Zr sulfide and where existing Fe₂Zr).
c) The residue of b) is treated with 20 ml of HF (1+20) at 40°C for 20 min and filtered (Separation of ZrN and fine ZrC).
d) The residue of c) is finally treated with 15 ml of HF (1+20) and 15 ml of conc HNO₃ at room temperature for 30 min and filtered (Coarse precipitate of ZrC is determined from the filtrate, and zirconium oxide from the insoluble residue).
e) Metallic zirconium is calculated by subtraction of combined zirconium fraction from the total amount of zirconium which is determined with use of a separate sample.