Development of Analysis Method for Sulfide in Steel with Chelating Agent of Copper

Copper sulfide (CuxS) has been frequently observed in steel samples, prepared using selective potentiostatic etching by electrolytic dissolution (SPEED). It is often the case that CuxS is detected unexpectedly from the precipitates extracted from steel samples by selective potentiostatic etching, al...

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Bibliographic Details
Published inTetsu-to-Hagane Vol. 104; no. 11; pp. 634 - 639
Main Authors Mizukami, Kazumi, Itabashi, Daisuke, Aimoto, Michihiro, Nishifuji, Masayuki
Format Journal Article
LanguageJapanese
Published The Iron and Steel Institute of Japan 01.11.2018
Subjects
AES
copper sulfide
CUSH
electrolytic dissolution
inclusion
SEM
SPEED method
Triethylenetetramine
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Summary:Copper sulfide (CuxS) has been frequently observed in steel samples, prepared using selective potentiostatic etching by electrolytic dissolution (SPEED). It is often the case that CuxS is detected unexpectedly from the precipitates extracted from steel samples by selective potentiostatic etching, although such CuxS formation during the heat treatment conducted is not anticipated by the thermodynamic equilibrium calculations.In this study, we observed such artificial CuxS along with manganese sulfide (MnS) precipitates, which were extracted from steel materials by SPEED, using secondary electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy. These CuxS-MnS sulfide complex would be formed by the following mechanism: as the solubility of CuxS is far bigger (i.e. 10 times or more) than that of MnS, Cu2+ ion dissolved from steel matrix would be exchanged with Mn2+ ion on the MnS surface during the etching process, leading to a formation of CuxS-MnS sulfide complex.In order to suppress the formation of such CuxS, we propose the use of following electrolyte: a non-aqaueous solutions of 4% methyl salicylate + 1% salicylic acid + 1% tetramethylammonium chloride (TMAC) + 5% Triethylenetetramine (TET) in volume fraction, in methyl alcohol (Cu ion selective hold etching by electrolytic dissolution, abridged as CUSH electrolyte). Then, this electrolyte was applied to precipitates in steel samples. It was effective to prevent the formation of sulfides in electrolyte, with the effect of metallic (Cu2+, Ag+, Pb+, etc.) chelating ability of TET.
ISSN:0021-1575
1883-2954
DOI:10.2355/tetsutohagane.TETSU-2018-056