Evaluation of the Influence of Flame Spraying Parameters on Microstructure and Electrical Conductivity of Al-12Si Coatings Deposited on Polyurethane Substrates

Influence of flame spraying parameters on coating microstructure and electrical conductivity of aluminum-12silicon coatings deposited on polyurethane (PU) substrates was studied. In order to evaluate the effect of the spray parameters on temperature distribution and its corresponding effect on coating characteristics, an analytical model based on a Green’s function approach was employed. It was found that the addition of air to the flame decreased the temperature within the substrate. Dynamic mechanical analysis (DMA) of the PU substrate revealed that the PU softened as the temperature increased. Therefore, by increasing the air pressure of the flame spray torch from 135 kPa to 170 kPa, the particles impacted a stiffer substrate. This led to higher deformation of the particles into splats upon impact, improved interlocking, and the overall coating had lower porosity and lower electrical resistance. This indicates that coating properties are sensitive to thermal spraying parameters when depositing on elastomeric materials.