Constellium's R&D on the Use of Power Ultrasound in Liquid Aluminium: An Overview

Our studies on both solid and hollow ceramic waveguides have demonstrated that power ultrasound promotes the wetting of otherwise non-reactive and non-wet ceramic materials. This opened the way to an innovative brazing process of aluminium alloys onto silicon nitride parts, which provides fatigue resistant coupling between the waveguide and the actuator. Use of power ultrasound also allows triggering the wetting of a waveguide used otherwise in the MHz range for detection purposes: this is the basis for the development of an ultrasonic Doppler velocimetry technique and an ultrasonic inclusion detector in liquid aluminium alloys which are being used and/or deployed at the industrial scale in our casthouses. These two measurement devices are presented in dedicated communications. Acoustophoresis has also been successfully tested and is a promising route for in-line inclusion separation in continuous casting troughs.