Advanced Particle Characterization for Improved Understanding of Spray Coating Quality

*Advanced Particle Characterization for Improved Understanding of Spray Coating Quality*
Prof. Eric A. Pirard¹, Mr. Florent Campana² and J. P. Janssen², ¹GeomaC, University of Liege, Chemin des chevreuils, 1, Sart Tilman B52, LIEGE, 4000, Belgium, ²Advanced Coating, Rue de l'avouerie, 7, LIEGE, 4000, Belgium The size and shape of individual particles are essential characteristics to control their behaviour during spraying. Thanks to recently available technology in powder image analysis, this paper investigates the correlation between the geometric properties of several thousands of particles and their flowability (Hall flowmeter) and apparent density (Scott volumeter). Both chromium carbide Cr₃C₂-NiCr 75/25 powders used for HVOF wear / oxidation resistant coatings and copper powders used in the cold spray process are studied. The behaviour of the HVOF spraying process is investigated for each powder by using in-flight measures of temperature, trajectory and velocity. Finally, the coating quality obtained for each powder is also assessed using metallographic image analysis.