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Quantitative Analysis of Zirconium Alloys Using Borate Fusion and Wavelength Dispersive X-Ray Fluorescence Spectrometry

Published

Author(s)

John R. Sieber, Anthony F. Marlow, Rick L. Paul, Charles A. Barber, Laura J. Wood, Lee L. Yu, Alaina Rieke, Amy Kutnerian, Jessica McCandless, Candace Wallace

Abstract

The National Institute of Standards and Technology (NIST) uses borate fusion, wavelength dispersive X-ray fluorescence (WDXRF) spectrometry and synthetic calibration standards for high performance, quantitative analyses of a wide range of materials, including alloys reacted and partially dissolved to be fused into borate beads. The change from metal matrix to low atomic number glass matrix preserves measurement sensitivity. Synthetic calibration standards are made to closely match the fused samples, and resulting calibrations enable very low overall uncertainties in final results. This approach is applied to zirconium alloys of ≥ 90 % Zr and up to 17 elements: Al, Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, P, Pb, Sn, Ta, Ti, V, and W. To demonstrate method capabilities, it is applied to Standard Reference Material (SRM) 360b Zirconium (Sn-Fe-Cr) Alloy, its replacement SRM 360c, and discontinued SRMs: 360, 360a, 1210, 1211, 1212a, 1213, 1214, 1215, 1234, 1235, 1236, 1237, 1238, and 1239. Eleven elements exhibit biases ≤ 5 % between published values and analyzed results. Additional validation was obtained using results from inductively coupled plasma (ICP) mass spectrometry, ICP optical emission spectrometry and prompt gamma-ray activation analysis. This new WDXRF method gives results of high enough quality to be used to certify elements in SRMs in conjunction with results from one or more independent methods. Several phenomena complicate the borate fusion approach. In the normal Zr dissolution approach using HNO3 + HF, Zr(NO3)4 is formed in solution and concentrated on taking the mixture to dryness. Zr(NO3)4 sublimes at low temperatures, causing specimens to smoke as the fusion program temperature exceeds 100 ℃. Rapidly heated Zr(NO3)4 may explode. The solution was to use just HF to digest the Zr alloys. High-purity ZrO2 and LiF were used for matrix matching of synthetic calibration standards, requiring determinations of trace elements in the high-purity ZrO2.
Citation
X-Ray Spectrometry

Keywords

X-ray fluorescence, borate fusion, elemental analysis, Standard Reference Material, quantification

Citation

Sieber, J. , Marlow, A. , Paul, R. , Barber, C. , Wood, L. , Yu, L. , Rieke, A. , Kutnerian, A. , McCandless, J. and Wallace, C. (2021), Quantitative Analysis of Zirconium Alloys Using Borate Fusion and Wavelength Dispersive X-Ray Fluorescence Spectrometry, X-Ray Spectrometry, [online], https://dx.doi.org/10.1002/xrs.3216 , http://dx.doi.org/10.1002/xrs.3216 (Accessed April 22, 2021)
Created January 25, 2021, Updated March 1, 2021