Effect of Surface Patterning on the Adhesive Friction

Abstract

Tribological properties play an important role in many applications that require low adhesion or non sticking surfaces; therefore, understanding the effect of the surface morphology on adhesion can allow for improved surfaces to be created. In the last 10 years, researchers have paid attention to the impact of the surface roughness on the tribological behaviour. As a result the idea of surface pattering or texturing has emerged as a mean of controlling the friction and adhesion between contacting surfaces. In this study, the effect of the different surface patterns with specifically selected parameters, such as the pattern size, and pattern density on the adhesion force which is measured by Atomic Force Microscope (AFM) is thoroughly investigated. First, micro laser dimples of different diameters’ (D’s) of 5, 10 and 20 μm are fabricated on air hardened tool steel samples using High quality–high power CuBr vapour laser. The distance (L), between the centers of two neighbouring circular dimples, were set to different values of 5, 10, 20, 40 and 80 μm. The AFM tip is modified so that the effect of the patterning on the adhesive force can be captured. A customized micro fabricated polystyrene particle of 120 μm in diameter is used as a tip attachment to the end of calibrated silicon nitride cantilever. The pull-off force versus displacement curves are recorded and used to estimate the average adhesion force for each surface pattern. It has been observed that selected surface patterns significantly decrease the adhesive forces compared to a flat surface. The ratio D/L, which represents the pattern density or the complement of the contact area establishes a well-defined trend of decrease of the adhesion force as D/L increases.

Friction, wear and corrosion: learning from nature

“…been proven that friction can be minimized at specifi c real contact area [20,21]. In two-and threedimensional fi nite element models, normal and sliding contact between a rigid indenter and elastic-plastic surfaces, which are textured by circular and hexagonal dimples of different sizes and densities, are simulated and analyzed [21].…”

Controlling the Depth of Microchannels Formed during Rolling-based Surface Texturing

“…It is applicable in various fields such as hydrodynamic bearing lubrication, modern aviation and high-speed rail industries, artificial body parts in medical field, etc. There have been many research reports that tribology and fluid flow characteristics in textured surface are sensitive to dimensional parameters, density and shape of the micro-channels or dimples [1][2][3] . Fredrik et al [4] investigated the influences of groove depth and width, Reynolds number and geometrical shape on surface texturing to the flow, load carrying capacity and friction force in hydrodynamic lubrica-tion of two parallel surfaces.…”