The main aim of the research work has been reached by the development of a process control system for melt atomization. Within reasonable accuracy limits, on-line PDA is able to predict the entire powder size by a single point measurement. Some restriction, such as the applicability of EPDA to LGA only for the low pressure region and the impossibility of PDA measurements in sprays with non-spherical particles are negligible compared to the final success with PDA during IGA. An on-line control for the gas atomization process has been realized, which is, in principle, also applicable for liquid gas and water atomization, where liquefied gas or water droplets are present simultaneously with molten metal droplets or already solidified metal particles. The required measurement technique, not only for droplet size and velocity, but also for the distinction between metal and atomizing medium has been demonstrated by various experiments. Finally, the application of the on-line PDA and the control loop systems has been successfully transferred from a laboratory system to a pilot plant, which works near to industrial conditions.
The aim of the researcxh proposal is to obtain an on-line process control of liquid gas and water atomization using extended Phase-Doppler-Anemometry(PDA). This will lead to higher quality of the powders and PM-products and an improvement of the production efficiency by the minimization of rejected material. This aim will be reached by fulfilling the following tasks:
- Construction and installation of a laboratory measurement system to determine particle velocity, size and concentration seperately for particles of different materials using extended PDA.
- Development of a prototype spraying system with integrated PDA
- Atomization tests for the evaluation of the parameters.
- Modelling of liquid gas and water atomization to obtain data for the development of a closed control loop for the optimization of powders.
- Set-up of a closed control-loop in the atomization units and verification.
Fulfilling these tasks, it will be possible to realize an on-line control of the melt spraying process, especially for liquid gas and water atomization, where, in some parts of the spray systems, liquid gas or water and molten metal drops will be present simultaneously.
This requires a measurement technique, not only for droplet size, velocity and concentration, but also to distinguish between droplet material and atomizing medium (by determining the refractive index of the dispersed phase). The most appropriate measurement technique for this is exteznded PDA.
Funding SchemeCSC - Cost-sharing contracts