Melt spraying using liquid atomizing fluids has been optimized giving: quality improvement of the final product and a reduction of operating and energy costs by better process control and minimized rejection of material. An on-line control of the major process parameters has been realized, defining a closed control loop and using extended phase-Doppler-anemometry (PDA) to measure particle size directly after the formation and to distinguish between molten particles and atomizing medium.
Some restrictions like the application of PDA to low pressure liquid gas atomization (LGA) and the impossibility of PDA in non-spherical particles are negligible compared to the final success of PDA in inert gas atomization (IGA). An on-line control of the melt spraying process, especially for gas and liquid gas atomization, where in some parts of the spray system, liquid-gas and molten metal droplets will be present simultaneously has been realized. The required measurement technique, not only for droplet size and velocity, but also to distinguish between droplet material and atomizing medium has been demonstrated by several atomization runs. The on-line PDA measurement was successfully carried out not only at a laboratory system but also under industrial conditions at an pilot atomization plant.