Force Interactions of Porous Silica Glass Microspheres against Mirror-Polished Stainless Steel in Nonaqueous Solvents

Abstract

Force interactions of porous silica particles against mirror-polished stainless steel surfaces were quantified in the presence of various solvents to facilitate processing of ceramics with less reliance on organic aids which subsequently need to be burned off. The results were compared to and found to be in good agreement to idealized models of van der Waals force interactions. Significantly, van der Waals attractive forces between steel surfaces and silica surfaces were minimized through the use of tetrahydrofuran and enhanced using methanol. The solvent selections were further extended to settling behavior and were found to follow the general trends determined by Stokes law. The methods presented herein can be extended to other real-world systems.

Repulsive van der Waals Forces Self-Limit Native Oxide Growth

“…When the condition ε 1 ≤ ε 2 ≤ ε 3 or ε 1 ≥ ε 2 ≥ ε 3 is met, in other words, when the dielectric response fucntion (DRF) of the intervening medium lies between those of the other two phases, the preceding equations give a negative Hamaker constant, indicating repulsion of the contacting material from the surface. Repulsive vdW forces are responsible for several natural phenomena, including the climbing of liquid helium up the walls of containers and the spreading of alkanes across the surface of water. , The majority of documented repulsive vdW interactions have been measured using the colloid probe technique for atomic force microscopy to measure forces between a particle and surface through a liquid-intervening medium. − …”