Effect of the Electrode Temperature on the Spark Discharge IV

Abstract

A study has been made on the influences of matrix and electrode temperature on spectrographic analysis of cast iron. White cast iron, ferritic gray cast iron, pearlitic gray cast iron, blackheart malleable iron, pearlitic malleable cast iron, ferritic spheroidal graphite cast iron, and pearlitic spheroidal graphite cast iron were used for the sample electrodes.The erosion and spectral line intensity of gray cast iron were remarkably higher than those of white, malleable or spheroidal cast irons. There was little difference between ferrite cast iron and pearlitic cast iron. These results show that the influence of matrix on spectrographic analysis depends mainly on the shape of graphite.When a heated sample-electrode was used, the influence of matrix on spectrographic analysis decreased. One working curve obtained by using sample electrode heated at 740°C makes it possibie to analyze all types of cast irons. The causes of the decrease in the matrix effect are thought to be violent oxidation and melting of the surface of the electrode, which homogenize the surface of diffecent cast irons.