Micro-particles spraying via non-stationary flame acceleration process

Thermal spraying techniques are widely used for aerospace applications allowing improve significantly thermal and electrical insulating properties and strength of structural materials. Over the past decades, detonation thermal spraying technology has established itself as a reliable and efficient approach for the deposition of a great variety of functional coatings actively used in the spacecraft industry. In the present paper, various aspects of the physical processes intrinsic for detonation spray are analyzed numerically. In particular, non-stationary processes of the flame development in the detonation gun barrel are considered in conjunction with the dynamics of the suspended microparticles. The benefits of tilted substrate orientation and incomplete barrel filling are studied and interpreted based on the analysis of gas-dynamical flows. Developed flow patterns are analyzed for the case without successful detonation initiation inside the barrel that allowed determining the effects of detonation gun barrel length, mixture reactivity, and inertia of particles. In particular, it is obtained that the parameters and distribution of the suspended phase can be optimized, taking into account the peculiarities of the carrying gas flows that emerged inside the detonation gun barrel to provide greater spraying efficiency. •Detonation spraying of microparticles into a substrate is analyzed numerically.•The effect of non-stationary flame development inside the detonation gun barrel is scrutinized.•Peculiarities of the gas-dynamical flows inside detonation gun define optimal spraying parameters.•Counterflow can prevent effective deposition of the micron-sized particles.•Variation of the substrate orientation allows increasing deposition efficiency.