THERMAL SPRAY METHOD INTEGRATING SELECTED REMOVAL OF PARTICULATES

摘要

A thermal spray system and method includes a hot gas generator with nozzle accelerating heated gas towards a substrate in the form of a gas column projecting onto the substrate surface as a spot. One or more feedstock injectors proximate the nozzle exit, directed towards the gas column, are connected to a feedstock source. The hot gas stream transfers heat and momentum to the feedstock, causing the feedstock particles to impact onto a substrate to form a coating. The system further comprises one or more liquid injectors proximate the nozzle exit, directed towards the axis, and connected to a source of liquid. The system controls the flow and velocity with which the liquid is injected, permitting control of the depth of penetration of the liquid into the gas column. The method selectively prevents suboptimal feedstock particulates from adhering to the substrate and provides for the in-situ removal of suboptimal deposits.

主权项

1. An integrated method used to form a coating on a substrate surface, comprising:
providing a source of heated gas and a nozzle for shaping heated gas into a gas stream column coaxial with the nozzle, the column projecting into a spot on the substrate surface, and providing one or more injectors used to inject feedstock into the gas stream column and used to inject a liquid into the gas stream column; establishing a feedstock profile and determining a portion of the feedstock profile as optimal and the balance of the feedstock profile as suboptimal; determining two volumetric regions within the gas stream column, including one first region wrapped around the axis of the column and a second region surrounding the first region and coaxial with it, the first region projecting into a spot on the substrate surface and the second region projecting into an annular ring on the substrate surface, the annular ring coaxial with the spot and surrounding it; injecting feedstock into the gas stream column and adjusting the injection parameters to control the depth of feedstock penetration into the gas stream column so that the optimal feedstock is entrained within the first region of the stream while the suboptimal feedstock is entrained within the second region of the stream; injecting a liquid into the gas stream column and adjusting the injection parameters to control the depth of liquid penetration into the gas stream column so that the liquid is entrained substantially within the second region of the stream, the liquid reducing the temperature of the suboptimal portion of the feedstock entrained within the second region of the stream, and the temperature reduction being sufficient to reduce or prevent the suboptimal feedstock adherence on the substrate surface; injecting a liquid into the gas stream column and adjusting the injection parameters to control the depth of liquid penetration into the gas stream column so that the liquid is entrained substantially within the second region of the stream so that the liquid impacts the substrate removing debris on and embedded in the substrate; and forming a coating on the substrate surface by depositing feedstock substantially from within the spot projected on the surface by the first region of the gas stream column, the coating, thus, consisting substantially of feedstock deposited with optimal temperature and velocity conditions.