Wettability of SiC and alumina particles by liquid Bi under liquid Al

In this paper a new experimental method to measure contact angle of liquid metals on solid particles under an immiscible second liquid metal is described. This includes efficient mixing of the three-phase system (two immiscible liquid metals with solid dispersed particles) with subsequent solidification. The micrographs of the cross sections of samples are analyzed for the distribution of the particles between the bulk of the two metals and the interface between them. As an alternative, exact positions of the particles can be measured at the interface between the two solidified metals. These two measurements are used to estimate the contact angle of one liquid metal on the solid particles under another, immiscible liquid metal. As an example, contact angle of a liquid Bi-rich alloy on SiC and alumina particles is measured under liquid Al-rich alloy. The liquid Bi-rich alloy was found to wet perfectly (with zero contact angle) alumina particles under liquid Al-rich alloy, while the contact angle on SiC is found to be around 88°. These contact angle data are shown to be relevant to control the stability of liquid metallic emulsions formed between the two immiscible liquid metals stabilized by the solid particles.