Protective thermal spray coatings for polymer matrix composites

Abstract

Polymer matrix composites were coated with metals, alloys and intermetallic compounds using the thermal spray coating technology. Air plasma spraying and flame spraying were the two spraying techniques primarily used during this entire study. Coatings were sprayed with two configuration; coatings with bond coating and coating without bond coating. Pilot runs were conducted to develop thermal spray process parameters for a two factor study, namely torch power and torch-substrate standoff distance, with other process parameters kept constant. Eventually a process window was established to carry out the final coating runs. Scanning electron microscopy was carried out to determine coating porosity and evaluate the microstructures and mechanical testing was performed to determine the bond strength and the erosion resistance of the coatings due to sand blasting. It is seen that the nickel aluminum intermetallic compound has better erosion resistance and bond strength than the nickel aluminum alloy. It is also seen that the process parameters, torch power and torch-substrate standoff distance do not significantly affect the coating properties.