Approaches to atomistic triple-line properties from first-principles

摘要

Different approaches to study wetting and adhesion by applying density-functional theory (DFT) methods are high-lighted. The ab initio thermodynamics method is used to demonstrate the link between the calculated work of separation and the work of adhesion and wetting angles from sessile-drop measurements. An approach to extend DFT calculations to the case of large-scale interfaces relevant for wetting systems is also discussed. Wetting and adhesion at metal-metal and metal-ceramic interfaces play a significant role in many techno-logical processes, such as brazing, lubrication, mold-casting and thin-film coatings. The ability to control wetting and adhesion requires a fundamental under-standing of the atomistic and electronic structures of the interfaces as a function of morphology, chemi- or physisorption of segregates, and of various environmen-tal variables, such as temperature and oxidizing atmo-sphere. In a wetting system, particularly near the triple-line, intricate heterophase interfaces are formed between liquid, solid and vapor phases of dissimilar materials, which may additionally include new reaction products [1,2]. The bonding at the interfaces is therefore complex and requires an atomistic modeling approach capable of accurately describing the ionic or metallic interactions in each of the phases separately, in addition to the mixtures of covalent, metallic and ionic bonding in the interface region, as, for example, in the case of metal-ceramic interfaces.