Advancement of in-flight alumina powder spheroidization process with water droplet injection using a small power DC-RF hybrid plasma flow system

Juyong Jang, Hidemasa Takana, Sangkyu Park, Hideya Nishiyama

Research output: Contribution to journalReview articlepeer-review

4 Citations (Scopus)

Abstract

The correlation between plasma thermofluid characteristics and alumina powder spheroidization processes with water droplet injection using a small power DC-RF hybrid plasma flow system was experimentally clarified. Micro-sized water droplets with a low water flow rate were injected into the tail of thermal plasma flow so as not to disturb the plasma flow directly. Injected water droplets were vaporized in the thermal plasma flow and were transported upstream in the plasma flow to the torch by the backflow. After dissociation of water, the production of hydrogen was detected by the optical emission spectroscopy in the downstream RF plasma flow. The emission area of the DC plasma jet expanded and elongated in the vicinity of the RF coils. Additionally, the emission area of RF plasma flow enlarged and was visible as red emission in the downstream RF plasma flow in the vicinity below the RF coils due to hydrogen production. Therefore, the plasma flow mixed with produced hydrogen increased the plasma enthalpy and the highest spheroidization rate of 97% was obtained at a water flow rate of 15 Sml/min and an atomizing gas flow rate of 8 Sl/min using a small power DC-RF hybrid plasma flow system.

Original languageEnglish
Pages (from-to)900-907
Number of pages8
JournalJournal of Thermal Spray Technology
Volume21
Issue number5
DOIs
Publication statusPublished - 2012 Sep

Keywords

  • DC-RF hybrid thermal plasma flow
  • alumina powder
  • plasma enthalpy
  • spheroidization
  • water droplet

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Materials Chemistry

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