Engulfment and pushing of Si3N4 and SiC particles during directional solidification of silicon under microgravity conditions
In this work, crystal growth experiments concerning particle incorporation behavior of SiC and Si3N4 particles in silicon melt growth were carried out on earth as well as under microgravity conditions. The experimental results are compared to calculations based on very simple theoretical models. It can be concluded that the critical growth velocity for the capture of particles with given size differs between SiC and Si3N4 particles because the thermal conductivity and interfacial energy of SiC and Si3N4 are different. Furthermore it seems that the lift force which pushes the particles away from the solid-liquid interface due to melt flow, might act only on larger particles. This could result in higher critical growth velocities under convective conditions.