Determination Of The Content Of Trace Impurities In Zirconium Samples

In recent years, clean energy has an increasingly proportion in the global energy infrastructure, while comparing to other clean energy sources, such as solar, hydrogen and wind energy, nuclear energy is more convenient, efficient and economic. Zirconium, known as "the first metal atomic age", is one of the most important materials in the nuclear industry due to excellent core performance, corrosion resistance, hydrogen absorption properties and radiation resistance. With the development of the nuclear power industry, the zirconium industry is also growing rapidly.trace elements of zirconium and zirconium alloys greatly affect the structure corrosion resistance, thermal stability and mechanical properties of materials,. Therefore, an accurate determination of impurity of zirconium and zirconium alloy elements is very necessary.In this paper, a experimental method was created to determine the content of trace impurities in zirconium by Glow discharge mass spectrometry. The working conditions in the experiment were optimized, instrument working parameters were:the discharge voltage:1200V; discharge current:50mA; discharge gas flow rate:440 mL/min. The results showed that Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Re Tl, Bi were not found, and the content of B, Na, Ca, V, Co, Zn, Ga, As, Y, Nb, Mo, Nd, Hf, W, Pb in two samples were less than 1μg/g, RSD value were between 3%～35%; the content ofMg, Ni, Cu, Ge, Cd were less than 10μg/g, RSD value were between 3%～35%; the content of Al, Ti, Cr, Mn, Pd, Pr were less than 75μg/g, RSD value were between 3%～ 35%.Inductively coupled plasma mass spectrometry was used to determine the variety of impurity elements in zirconium samples. HF+HNO3 were used to dissolve samples. The most suitable acidity was 2%(V/V) HNO3; four internal standard elements were select to reducing spectral interference according to the mass range and recovery rates. The detection limits were less than 0.1ng/mL (Sn was 0.46ng/mL). The content of Be, B, Ca, V, Cr, Mn, Co, Zn, As, Se, Y, Cd, Sn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Re, Tl, Pb in both of three samples were less than 1μg/g, and the content of Mg, Al, K, Ni, Cu, Nb, Pd, Ta, W were less than 10μg/g, and the RSD values were between 1%～ 30%, the main impurities were Ti, Fe, Mo, Hf, the RSD values were between 1%～15%. The recovery rates were between 90～108%. That showed that the precision and accuracy of this method were meeting the analysis requirements. The results of uncertainty evaluation showed that the main factors affecting the measurement uncertainty for determination of impurities in zirconium measured by inductively coupled plasma mass spectrometry are measurement repeatability and concentration of titanium in sample solution, mainly comes from calibration curve fitting.Compared with the results of bulk zircon samples determined by glow discharge mass spectrometry and inductively coupled plasma mass spectrometry, Elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Re, Tl were not found neither. And there were not differences in orders of magnitude of B, V, Co, Ni, Cu, Zn, As, Y, Sn, Hf, Ta, W, Pb. Because of impurities polluting in samples dissolving, the results of Na, Ca, Nb by ICP-MS were higher than the real contents. And because of hindering, the results of Cr, Al, Mn by GD-MS were higher than that by ICP-MS.Frequency heating-infrared absorption method was adapted to measure the content of carbon, hydrogen, nitrogen, oxygen in the sample. Carbon content determined by frequency infrared carbon and sulfur analyzer. The best optimum heating power is 70% of the maximum. Results of analysis showed that different standards to calibrate the instrument sample material would lead to significant different determinations, So in order to the higher the accuracy of the measurement results, we should choose the standard that has more matching matrix and standard values close to the carbon content of materials to calibrate the instrument. Standard in this paper was titanium GBW02502 (C%=0.012%).The carbon content of three samples were less than 0.02%, and RSD values were less than 8%. The results of uncertainty evaluation showed that the main factors affecting the measurement uncertainty are the standard value of standard material, repeatable experiments and calibration measurement variability. Hydroxide, nitrogen and oxygen were determined bya nitrogen hydroxide union tester, the content of hydrogen, nitrogen were less than 0.005%, and the oxygen was less than 0.01%.