Surface energy, surface topography and adhesion

Abstract

In this paper are discussed some of the fundamental principles which are relevant to an understanding of the influence that interfacial roughness may have on adhesion. The surface energies of the adhesive, substrate and of the interface between them determine the extent of wetting or spreading at equilibrium. Numerical values for surface energies may be obtained either from contact angle measurements or from analysing force-displacement curves obtained from the surface forces apparatus. The extent to which the relationships, appropriate for plane surfaces, may be modified to take into account interfacial roughness are discussed. For modest extents of roughness, the application of a simple roughness factor may be satisfactory, but this is unrealistic for many of the practical surfaces of relevance to adhesive technology which are very rough, and is ultimately meaningless, if the surface is fractal in nature. Some examples are discussed of published work involving polymer-metal and polymer-polymer adhesion, where the roughness of the interface exerts a significant influence on the adhesion obtained. Roughness over a range of scales from microns to nanometres may strengthen an interface, increasing fracture energy by allowing bulk energy dissipating processes to be activated when the bond is stressed.

Liquid infused porous surfaces for mineral fouling mitigation

“…Such observations are in accordance with the high density of calcium carbonate observed on noninfused PPy and PTFE to a lower extent in the current work. Infusing the micro-porous PPy with lubricants lower the surface energy of the interface which increase the barrier energy for heterogeneous nucleation [29][30][31][32] and also help reducing the adhesion of solid particles onto the surface [33,34] while maintaining a smooth surface; deflect free down to the molecular scale [19]. It is this multifunctional design that provides the liquid-infused porous surfaces with the promising antifouling properties shown in Figure 4.…”

Treatment of Steel Surfaces for Effective Adhesive Bonding

“…Various parameters have been proposed to represent the surface roughness/topography among which the so-called fractal dimension D appears to the most popular (Amada and Satoh 2000;Packham 2003). The fractal dimension is normally found using the "box counting method" (Amada and Satoh 2000), and a larger fractal dimension generally means a rougher topography.…”

Serration effects on interfacial cracks

“…Materials scientists are increasingly interested in fractures at the interface between two dissimilar materials, because they are fundamental for understanding thin-film coatings [Hutchinson and Suo 1992;Diao and Kato 1994;Mishnaevsky and Gross 2005], electronic packaging, adhesion [Straffelini 2001;Packham 2003], and composites and biomaterials [Wang and Agrawal 2000;Lucksanasombool et al 2003]. Experiments cumulatively show that the waviness at the interface profoundly effects interfacial crack propagation.…”

“…Previously, serrations and hackles were modeled by first identifying a scalar material parameter with the interfacial roughness and then investigating its effect on interfacial fracture and strength [Cao and Evans 1989;Ramulu et al 2001;Lucksanasombool et al 2003;Packham 2003]. Because the method is simple, it fails to capture micromechanical and microgeometric details at the interface and around the crack's tip.…”