Determination of hafnium in zirconium materials

Abstract

An arc atomic emission technique of hafnium determination in zirconium is developed and tested. The study was carried out on a PGS-2 spectrometer equipped with MAÉS analyzer and information processing software «Atom 3.3». («VMK-Optoélektronika», Novosibirsk). Excitation of spectra of pre-oxidized metal was carried out using a medium-frequency generator «Vesuvius» («VMK-Optoélektronika», Novosibirsk). Analytical line of hafnium was free of spectral overlap with the lines of zirconium. We have set a current of the AC arc discharge (20 A), exposure time (30 sec) and the form of the electrode into which the sample is placed («narrow crater») are selected. The effect of buffering additives (graphite powder, bismuth fluoride) on the intensity of the analyte lines was studied. It is shown that high sensitivity of the analyte is observed for oxidized material without additives. Reduction of the random error attributed to the influence of conditions of spectrum excitation and sample preparation is achieved using the intensity ratio of the analyte line and zirconium as an analytical signal. Recommendations regarding preparation of the samples for calibration are given. The lower limit of the determined concentration is 0.01% with a relative standard deviation in repeatability 3%.