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Spraying of Metallic Powders by Hybrid Gas/Water Torch and the Effects of Inert Gas Shrouding


A hybrid DC arc plasma torch, combining water and gas stabilization, offers a high flexibility in plasma characteristics. These can be controlled in a wide range by the torch operational parameters, such as arc current and secondary gas flow rate. In this study, their influence on plasma spraying of tungsten and copper was investigated. To suppress the in-flight oxidation of the metals, inert gas shrouding was applied. In-flight particle diagnostics and analysis of free-flight particles and coatings was performed for spraying experiments in the open atmosphere and with argon shrouding. Both in-flight particle behavior and coating properties were found to be sensitive to the torch parameters. The application of shrouding was found to affect particle in-flight parameters, reduce the oxide content in the coatings and generally improve their properties, such as thermal conductivity. However, a different degree of these effects was observed for copper and tungsten.

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The authors gratefully acknowledge the financial support of Czech Ministry of Industry and Trade under project No. FR-TI2/702 and No. FR-TI2/561.

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Correspondence to T. Kavka.

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This article is an invited paper selected from presentations at the 2011 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Thermal Spray 2011: Proceedings of the International Thermal Spray Conference, Hamburg, Germany, September 27-29, 2011, Basil R. Marple, Arvind Agarwal, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and André McDonald, Ed., ASM International, Materials Park, OH, 2011.

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Kavka, T., Matějíček, J., Ctibor, P. et al. Spraying of Metallic Powders by Hybrid Gas/Water Torch and the Effects of Inert Gas Shrouding. J Therm Spray Tech 21, 695–705 (2012).

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  • copper
  • gas shroud
  • hybrid water-gas plasma torch
  • plasma facing materials
  • plasma spraying
  • tungsten