Effects of reduction temperature and diluent content on the properties of high-purity tantalum powder prepared using the Hunter process

초록

The Hunter process is predominantly used to manufacture high-purity Ta powder. Among the various physical properties of the Ta powder, its impurity content is particularly crucial. In this study, the process temperature at which a liquid pool of raw material and diluent can be formed and the corresponding amount of diluent were analyzed by performing thermodynamic simulations using FactSage and HSC Chemistry software. Based on the results of the thermodynamic simulations, Ta powder was prepared at process temperatures of 700-800 degrees C and a specific amount of NaCl at each temperature. Thereafter, the prepared Ta powder was recovered and a post-treatment process was performed to ensure purity. The characteristics of the recovered Ta powder were evalu-ated according to each process condition by oxygen/nitrogen/hydrogen analysis, scanning electron microscopy/ energy-dispersive X-ray spectroscopy, glow discharge-mass spectrometry, and X-ray diffractometry. The syn-thesized Ta powders were confirmed to exhibit purities >99.95% and oxygen, nitrogen, and hydrogen con-centrations of 447, 21, and 10 ppm, respectively. The characterization results indicated that the produced Ta powders were fabricated entirely in a single phase with high purity and recovery rates. Finally, process opti-mization was achieved for manufacturing high-purity (>= 3 N5) Ta powder with controllable impurities.

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