A fundamental study has been made on application of the cold HNO
3. method to extraction and analysis of inclusions in steel, particularly in rimmed steel. Potentials in cold HNO
3 media are measured with use of a Pt electrode against saturated calomel electrode, and chemical behaviors of several compounds, in cold HNO
3 are also investigated.
The followings are the results obtained;
(1) The potential in cold HNO
3 is found to vary remarkably around the concentration of (1+1) of HNO
3, thus showing higher value at the higher concentration whereas lower one at the lower concentration, of HNO
3.
(2) Direction of current between pure iron electrode and S. C. E. in cold-HNO
3. cell is observed to be different at the concentrations of (2+1) and (1+1) of HNO
3.
(3) Ferrous iron compounds such as FeO, FeS and FeO-silicate are stable in cold HNO
3, but MnO, MnS and compounds containing much quantity of Mn component are easily attacked by cold HNO
3(4) The cold HNO
3 method is found useful for extraction and analysis of inclusions in steel, having an advantage of choice of adequate concentration and temperature of cold HNO
3 according to the purpose.
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