Floating of SiC particles in a Zn-Al filler metal

Floating of SiC particles in a Zn-Al filler metal was investigated as functions of isothermal holding time, holding temperature, particle volume fraction and size. The floating distance increased with isothermal holding time until a stabilized condition was reached with all particles floating on the top of the melt. The floating distance increased significantly with increasing holding temperature and particle size and decreased with increasing particle volume fraction. The measured floating rates deviated significantly from those predicted by the modified Stokes' law at relatively low holding temperatures, but the correspondence turned better with increasing holding temperature. Although the effect of particle volume fraction had been taken into account in the modified Stokes' law, the correspondence was not good between the measured and the calculated values at various particle volume fractions. The measured floating rates which increased with particle size were much lower than the calculated values, particularly for large particle sizes. (C) 2007 Elsevier B.V. All rights reserved.