A new gasdynamical coating method using detonation tube technology

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A novel detonation-driven spray technique has been developed and tested, accelerating particles in a high enthalpy nozzle flow. This method achieves average particle velocities between 1500 m/s and 1800 m/s, significantly higher than the 1000 m/s maximum seen in conventional thermal spray applications. This advancement allows for the use of spray materials with critical bonding velocities below 1000 m/s, enhancing coating quality as impact velocities approach the upper erosion velocity. The technique utilizes detonation-driven shock tunnel technology to operate the nozzle intermittently at frequencies up to 5 Hz, creating high reservoir conditions through hydrogen detonation. A specially designed particle feeder injects particles into the quasi-steady nozzle flow (30 bar, 3600 K) at variable positions along the nozzle axis, allowing control over particle temperature and velocity, with theoretical temperatures nearing or exceeding material melting points. Various measurement techniques, including PIV, have been employed to analyze flow features and particle behavior. Initial coating samples with different material pairings exhibit excellent microhardness and low porosity. The variability in process parameters presents significant optimization potential for existing coatings and exploration of new material combinations.