Electrostatic spray deposition (ESD) of 'self organizing' TiO2-epoxy powder paints: experimental analysis and numerical modelling

This paper deals with an electrostatic spray deposition (ESD) process of 'self organizing' TiO2-epoxy powder paints on metal substrates. The first part of the paper focuses on analyzing the influence of both electrical and aerodynamic operational parameters on ESD process. Design of experiments (DOE) was used to plan experimental trials. ANOVA tables were calculated and used as support instruments to interpret the experimental findings and to understand physical phenomena involved in the deposition process as well as the role of TiO2. As a result, several process maps were produced which report consistent trends in coating thickness versus operational parameters. Best deposition conditions could therefore be deduced. Initial attempts to produce 'self-organizing' TiO2-based gradient coatings are also discussed. The second part of the paper focuses on assessing the influence of the target locations in the deposition booth on coating thickness of the TiO2-epoxy films. Design of experiments (DOE) was once again used to plan experimental trials and ANOVA tables were also calculated. Experimental findings are interpreted and the role of TiO2 is also investigated. This leads to the best target locations being deduced. Finally, neural network solutions able to predict coating thickness according to settings of operational parameters were developed and validated by comparing them with experimental data and a first approximation regression model.