Spectrochemical Analysis of High-Temperature Alloys by Spark Excitation in Argon and Nitrogen
SourceSpark excitation of high-temperature alloys in atmospheres of argon, nitrogen, and ambient air were investigated. Compared to air, argon or nitrogen provide the following advantages: (1) Volatilization rates are more constant in time. (2) Background intensities are constant and independent of alloy composition. (3) Effects of metallurgical history on specimen excitation are minimized. Also, self-absorption is markedly reduced in argon. Because of these characteristics, calibration is simplified, and it is possible to analyze many different types of alloys with the same set of analytical curves. This results in a marked reduction in the number of primary standards needed for initial calibration. An effective device for shielding the spark excitation column and specimen surface with a stream of gas is described. Data are presented showing application of the method of excitation in argon and nitrogen to the analysis of a variety of high-temperature alloys.