This paper presents the influence of a heated sample electrode on spectrochemical analysis by spark discharge. Fe-Co, Fe-Ni, Fe-Cu, Fe-Al, Fe-Cr, Fe-Mn binary alloys are used for the sample electrodes.
Spectral line intensities vary with the electrode temperature. Intensity change of spect ral lines emitted from the sample electrode containing an alloy element lower than 5 percent is similar to that of spectral lines from a pure iron electrode ; that is, the line intensities increase markedly with rising temperature in a range from 300°C to 500°C and increase gradually in a range higher than 500°C, approaching a definite value. The line intensity ratio [
I (alloy element) /
I (Fe)] for the sample, whose alloy element is difficult to be oxygenized, decreases markedly with rising temperature in a range from 300°C to 500°C The ratio for the sample containing an alloy element that is easily oxygenized; increases slightly with rising temperature. Concentration gradient of elements in the cross section of the crater has been studied with EPMA. The result shows that change in the intensity ratio is caused by selective oxidation of alloy element.
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