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

Yong Kwan Lee, Hyun Chul Kim, Namhun Kwon, Jae Jin Sim, Mi Hye Lee, Soong Ju Oh, Seok Jun Seo, Jae Hong Shin, Kyoungtae Park

Research output: Contribution to journalArticlepeer-review


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 °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 evaluated 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 synthesized Ta powders were confirmed to exhibit purities >99.95% and oxygen, nitrogen, and hydrogen concentrations 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 optimization was achieved for manufacturing high-purity (≥3 N5) Ta powder with controllable impurities.

Original languageEnglish
Article number106128
JournalInternational Journal of Refractory Metals and Hard Materials
Publication statusPublished - 2023 Apr

Bibliographical note

Funding Information:
This study was funded by the Korea Institute of Energy Technology Evaluation and Planning (No. 20195210100070 , development of upcycling technology for low-grade tantalum waste resources using dry and wet integrated processes) and funded by an internal R&D program(Development of material preparation/ surface treatment/ post-processing for molten metal based hard-facing technology with higher than 40 HRC harness) of the Korea Institute of Industrial Technology (KITECH) funded by the Ministry of Strategy and Finance, Republic of Korea.

Publisher Copyright:
© 2023


  • Diluent
  • Hunter process
  • Potassium heptafluorotantalate
  • Reduction temperature
  • Tantalum

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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