Relationships between NiCrBSi particle characteristics and corresponding coating properties using different thermal spraying processes

Because the microstructure and physical properties of a thermally sprayed coating are determined by the dynamics of the particles interacting with the spray jet, different processes were tested in order to explore the effects of process variables to particle characteristics and to coating quality. The NiCrBSi powder was sprayed successively with plasma, flame and HVOF process. Standard parameters specified by previous researches were followed for this operation. The DPV 2000 measurement system was used to monitor particle characteristics during their flight into the spray. Then, the coatings were realized at the position corresponding to the DPV measurements. The coatings were characterized in term of microstructure and composition, hardness, Young modulus, porosity and oxide level. The results revealed significant modifications in coating properties depending on the used spray process. Comparing the particle characteristics obtained successively with the different processes allows to better understand the properties of the formed coatings and to investigate the causes of a coating quality changes. Differences were interpreted based on in-flight diagnostic results. (c) 2004 Elsevier B.V. All rights reserved.