On the Effect of Electrode Temperature of Spark Discharge

Abstract

A study has been made on the influences of electrode temperature on spectral line intensities and working curves in spetrographic analysis of cast iron. Both white cast iron and gray cast iron were used for the sample electrodes.The iron spectral line intensity increases markedly with rising temperature in a range from 300°C to 500°C, and it increases gradually in a range higher than 500°C, approaching a definite value.When the electrode temperature is lower than 300°C, the iron line intensity of gray iron is stronger than that of white iron. Difference between the intensities of gray and white irons decreases gradually with rising .temperature and becomes very small at above 500°C.Intensity ratios of alloying elements such as Si, Mn, Al, Ni, Cu, Cr and Ti to iron also depend upon the matrix of cast iron. Its dependence, however, decreases when the electrode is heated. To determine Si, Al, and Ni in cast iron without heating the sample electrode, it is necessary to prepare working curves for gray iron and white iron, respectively. If the heated electrode is used, only one working curve enables one to analyze samples of both cast irons.