In-Flight Oxidation of Fe-Based Amorphous Particle During HVAF Spraying: Numerical Simulation and Experiment.

Understanding formation and evolution of oxidation in the thermal spray process is of significance since it affects greatly the corrosion resistance of coatings. In this work, the growth of oxide layers on in-flight Fe-based amorphous powders in high velocity air fuel (HVAF) thermal spray process was studied in detail by means of numerical and experimental methods. An oxidation model, based on the Lagrangian manner, was used to track the Fe-based amorphous particles. The simulation results showed that the increment of oxide layer thickness was codetermined by oxygen partial pressure of in-flight particles and particle temperature. It occurred primarily in the combustion chamber and barrel rather than the outflow field stage after flame flow. Furthermore, the relationship between in-flight particle oxidation and spray parameters was predicted by simulation. The optimal combustion chamber pressure is 90 psi and the optimal oxygen fuel ratio is 2.95. These were verified by the microstructural feature of in-flight collected particles, and low-oxidation Fe-based amorphous coating was obtained by HVAF utilizing the predicted spray parameters. This work offers us beneficial guidance of fabricating low-defect amorphous metallic coating. [ABSTRACT FROM AUTHOR]