Two powder stream diagnostics for laser deposition processes Available to Purchase

The velocity, density, and mass flow of particles suspended in a subsonic gas stream are important aspects of plasma spray and laser deposition processes. This paper will focus on two optical diagnostic techniques applied to the metal powder streams out of a powder feeder and into a new nozzle developed specifically for such applications. An important characteristic of the new powder nozzle is that it produces a very small column (approximately 1 mm diameter) of powder which can be used for small focus laser deposition and cladding processes. Laser Doppler Velocimetry (LDV) was applied to the nozzle’s output to better understand the kinetic parameters (velocity and spatial density) of exiting particles. Optical scattering of the powder stream was used to measure the total mass flow into the nozzle. Different light scattering detector scenarios applied to the input powder stream were used to identify signals useful for mass flow feedback control. Both of these techniques have the advantages of being fast, non-invasive diagnostics of the powder flow characteristics, and with a well established theoretical framework. Together, or individually, these diagnostics can provide real-time control or post-process analysis of the powder stream.