The Determination of Silicon, Chromium and Cobalt in Steels by Proton-Induced Prompt Photon Spectrometry

Prompt ¿-ray spectra from pure samples of Si, Cr and Co induced by protons between 3.5 and 6.0 MeV were used to evaluate the analytical feasability of the method and to calculate interference-free sensitivities. The bombarding energy was selected from experimentally determined sensitivity curves and the method was tested on NBS standard steels. Using protons of 4.0 and 4.5 MeV the Si-content was determined from the yield of the 1779-keV 29Si p(l,0) ¿-ray with a relative precision of 2.1 and 0.6% resp. Possible sources of spectrographic interference were Al and P but these elements were not present in the steel in significant concentrations. The Cr-content was found from the 378-keV 53Cr n(1,0) ¿-ray with a relative precision of 1.3 and 1.6% resp. Likely interference from ¿-rays between 375 and 380 keV could come from Ca, Sc, Fe, Se, Cd and W of which Fe and W were the most serious. Co was determined from the yield of the 343-keV 59Co n(l,0) ¿-ray with a relative precision of 2.3% using 4.5 MeV protons. Other ¿-rays from Co of 878, 1190, 1337 and 1948 keV could also be used. Routine analyses lasted 15-20 min but longer periods were needed when low concentrations were measured. The method was found to be suitable for steels containing Si above 0.01%, Cr above 0.12% and Co above 0.10% by mass.