Journal of Thermal Spray Technology

, Volume 12, Issue 2, pp 258–264

Effect of direct-current plasma fluctuations on in-flight particle parameters: Part II

  • J. F. Bisson
  • C. Moreau
Reviewed Papers

DOI: 10.1361/105996303770348375

Cite this article as:
Bisson, J.F. & Moreau, C. J Therm Spray Tech (2003) 12: 258. doi:10.1361/105996303770348375

Abstract

This paper is the continuation of previous work,[1] in which plasma fluctuations were shown to produce significant time-dependent variations in the in-flight particle temperature and velocity, as well as in the number of detected particles. In this paper, the impact of the plasma fluctuations on the coating microstructure and deposition efficiency is demonstrated. Alumina coatings and deposition efficiencies, obtained with two sets of spray conditions showing similar in-flight particle conditions (velocity and temperature) with the DPV-2000 but displaying very different voltage fluctuations, are compared. The coating produced in the less stable plasma condition (C-I) is found to be more porous and contains a larger number of unmelted particles than the other coating produced in more steady plasma conditions (C-II). Moreover, condition C-I yields a significantly lower deposition efficiency. Such large discrepancies must be traced back to the physical characteristics of the particle jet. Laser illumination of the particle jet is used to probe particles too cold to be detected by pyrometric means. Cold particles are found in a much larger proportion in C-I than in C-II. They are ascribed to particles that are injected when the plasma is in a low enthalpy state. Periodic time-dependent variations in the in-flight characteristics of cold and hot particles, synchronous with the voltage fluctuations, are revealed.

Keywords

alumina control diagnostics microstructures plasma fluctuations 

Copyright information

© ASM International 2003

Authors and Affiliations

  • J. F. Bisson
    • 1
  • C. Moreau
    • 1
  1. 1.National Research Council of CanadaIndustrial Materials InstituteBouchervilleCanada

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