Search

This paper presents an experimental validation of an in situ ultrasound technique for tracking the solid-liquid interface during directional solidification of photovoltaic silicon. Ultrasound bursts are introduced from the top into the melt via the tip of a carbon glass waveguide directly plunged into the liquid. Several runs of solidification have been conducted using the same waveguide thus demonstrating its reusability, its mechanical resilience and its appropriate acoustical and chemical compatibility with the melt. We present the times of flight analysis to track the location of the solid-liquid interface. As part of the signal crosses the solidifying ingot, we also measure $c_s$ , the average celerity of sound waves in the solid. Since $c_s$ exhibits a significant dependance on crystal orientation, we consider the possibility to use the echoes to extract some information on the crystalline orientation in the ingot. By quantifying the uncertainties and their dependence with the duration of the experiment in particular, we outline the conditions necessary to detect accurately the average orientation in the solid.

International audience; The aim of this experimental and numerical work is to determine the mass transfer at the wall of a steel cylinder rotating within liquid Lead-Bismuth blend. This is a crucial parameter for the analysis of corrosion tests performed in the CICLAD experimental setup for the investigation of flow assisted corrosion of steel by liquid metals. As a reliable numerical modelling must rely on experimental validation, and since no direct wall mass transfer measurement is possible in CICLAD, a scaled electrochemical model has been achieved. Modelling the turbulence in this rotating configuration is shown to require the use of a Reynolds-Stress Model. A sensitivity to the Schmidt number is observed in the numerical simulations representing the measured mass transfer in the electrochemical model. Simulations dedicated to liquid Pb-Bi are thus presented in addition to those dedicated to the aqueous solution used in the electrochemical model. Following correlations are proposed for the prediction of Fe mass transfer at the wall of a steel rotating cylinder in liquid Pb-Bi: Sh=1.9x10-1 (Re 2 Sc) 0.31 for 2x10 9