Kinetic Metallization: Nozzle Design
The deposition nozzle is designed with a specialized contour that produces maximum velocity in the metal particles. Inovati scientists produced the critical designs for these nozzles using an Inovati developed Computational Fluid Dynamic (CFD) algorithm.
Additionally, the nozzle contour must not be subject to wear, or the performance (deposition efficiency) of the nozzle will degrade over time. Inovati has identified combinations of materials and fabrication technology that create the highest velocity possible with extremely long nozzle life.
In impact consolidation processes, solid-state deformation and thus consolidation of powders into coatings and freestanding shapes is achieved exclusively through particle kinetic energy. For a particle of given mass the sole means of increasing particle kinetic energy is to increase particle velocity. Inovati learned that to achieve high particle velocity at low cost, the supersonic gas velocities were not desirable. Furthermore, once a gas exceeds Mach 1, it must eventually slow below supersonic velocity. This consequence produces shockwave phenomena, which further decrease particle velocity and thus deposition efficiency and coating quality. For more details, please review the graphical representations below with particular attention to particle velocity vs. gas velocity for sonic (KM) and supersonic processes.
The supersonic approach is to accelerate gas to the highest velocity possible in an attempt to accelerate particles to the highest velocity possible. However, once past the nozzle throat, in the exit duct, a supersonic gas has very low density and low pressure, which eliminates its ability to push particles effectively. The sonic approach (KM) is to accelerate gas to just below sonic velocity so that the gas density in the exit duct (after the nozzle's throat) remains essentially equal to that at the nozzle throat. Thus the product of the gas density and the gas velocity produces higher aerodynamic drag for a longer period of time and produces particles of higher velocity than the supersonic alternative. This allows us to operate at as little as 1/10th the pressure of competing processes, which equates to lower helium consumption costs. This advantage over supersonic processes is only enhanced, as helium recycling is included in the picture.