Experimental Study of the Relationship between the Free Energy of Adhesion and the Repulsive Force between a Particle and a Solidification Front

Abstract

By observing particles being pushed up an incline by an advancing solidification front, the repulsive force, FR, between the front and the particle is measured. This is done with three particle-melt systems, acetal particles in benzophenone, biphenyl, and salol, where the free energy of particle adhesion to the solidification front, ΔFadh, is known. A linear relationship is found to exist between FR and ΔFadh for these three particle-melt systems. Having values for FR and ΔFadh it is possible to calculate the minimum separation distance, h, between the particle and the solidification front below which particle engulfment will occur. For all three particle-melt systems h was found to be essentially the same, 20 nm. In particle-melt systems where h is constant, theory would predict that a linear relationship exists between FR and ΔFadh. The fact that this relationship was found to exist between values of FR measured directly and ΔFadh calculated from contact angle measurements using an equation of state for interfacial tensions provides strong support for the validity of the approach used to determine ΔFadh.