Determination of Ge in Au alloys using sodium hypophosphite and potassium iodate potentiometric titration method
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Rare Met. DOI 10.1007/s12598-014-0375-3
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Determination of Ge in Au alloys using sodium hypophosphite and potassium iodate potentiometric titration method Shou-Li Han, Xiao-Tang He, Jun-Mei Guo, Zhao-Ying Ren, Li-Ya Zhu, Liang-Wei Chen*, Qing-Nan Shi, Jia-Hong Yi
Received: 27 September 2013 / Revised: 20 February 2014 / Accepted: 13 August 2014 Ó The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2014
Abstract This paper presents a new method of determining Ge in AuGe alloys by potassium iodate (KIO3) potentiometric titration when Ge(II) and Au(0) are simultaneously reduced from Ge(IV) and Au(III) by sodium hypophosphite rather than by distillation separation. The influences of such conditions as the reduction acidity, the dosage of sodium hypophosphite and the reduction time on the determination of Ge were studied. Ge in AuGe alloys such as AuGe12, AuGeNi12-2, AuAgGe18.8-12.5, and AuAgGeNi43.8-6-0.2 was measured with the relative standard deviation (RSD) of 0.10 %–0.31 % and the recoveries of added standard Ge in sample of 99.40 %–100.40 % under the conditions of 0.40–0.80 molL-1 HCl, 3.3 molL-1 H3PO4, 15 g sodium hypophosphite, and reduction time of 40 min. The new method presented is of high accuracy in results, good stability and sensibility in end-point, and easy operation and strong selectivity of determination. Keywords Ge determination; AuGe alloy; Sodium hypophosphite; Potassium iodate; Potentiometric titration
1 Introduction Ge-containing Au alloy, characterized by low contact resistance, encapsulation temperature, thermal expansion S.-L. Han, Z.-Y. Ren, L.-W. Chen*, Q.-N. Shi, J.-H. Yi School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China e-mail: [email protected] S.-L. Han, X.-T. He, J.-M. Guo, L.-Y. Zhu State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Sino-Platinum Metals Resources (Yimen) Co. Ltd., Yimen 651100, China
coefficient, good wettability, conductivity and heat conductivity, is one of the important military products because of its key roles and wide applications in the electronic encapsulation and industry [1]. The inductive coupling plasma atomic emission spectrographic method (ICP-AES), with the advantages of accurate results, good selectivity, fast analysis, wide linearity range, etc., is widely applied in the determination of Ge in base metal alloys [2–5]. Although the method of KIO 3 starch indication titration to determine Ge has an advantage of accurate results, there are more disadvantages when the starch is used as the indicator which is interfered by oxidation reducibility and color ions. Color ions have to be separated by pre-distillation, which easily leads to the loss of Ge due to complicate operation and long process analysis [6–10]. In addition, when the titrate reaches the end-point, blue color of iodine starchy fades in 15 s. It is required that the titration speed of samples should be consistent with that of
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