Wettability and Work of Adhesion of Nonreactive Liquid Metals on Silica

Abstract

Wettability of silica by gold, silicon, and lead has been determined by the sessile‐drop method. The contact angle, θ, and the work of adhesion, W , have been found to be 143° and 227 mJ·m −2 for gold at 1353 K, 87° and 869 mJ·m −2 for silicon at 1723 K, and 120° and 203 mJ·m −2 for lead at 1000 K. Thermodynamic adhesion between silica and nonreactive pure metals has been analyzed using models for metal‐oxide bonds. Models based on the assumption that only van der Waals interactions and/or metal‐oxygen chemical bonds exist at the metal‐oxide interface are unsuited for explaining the relative variations in the W values. A valid model can be accomplished by using an empirical equation which takes into account both metal‐oxygen and metal‐oxide chemical bonds. It appears that chemical bonds exist at the interface even for nonreactive metal‐ionocovalent oxide systems.