The influence of HVOF spraying parameters on the microstructure, residual stress and cavitation resistance of FeMnCrSi coatings

Abstract

Thermal spray processes can be used to apply erosion-resistant coatings to components. One of the most important is the HVOF (High Velocity Oxygen Fuel) process, which is characterized by lower temperatures and higher projection velocities than arc and plasma thermal spray processes. This study sought to analyze the influence of three process parameters (standoff distance, fuel/oxygen ratio and powder feed rate) on particle velocity, particle temperature, coating microstructure and residual stress formation in FeMnCrSi coatings deposited by a liquid-fuel HVOF process and the effect in turn of coating microstructure and residual stress on coating cavitation resistance. An increase in fuel flow and reduction in standoff distance resulted in increased particle velocity but did not significantly affect particle temperature. Varying the process parameters had a significant influence on the residual stress in the coatings. A correlation between compressive residual stress, increased hardness and reduced mass loss rate during ultrasonic cavitation testing was observed.