Adhesion Reduction of Diamond-Like Carbon Films Based on Different Contact Geometries by Using an AFM

Abstract

The effect of reducing adhesion force by coating with a metal-containing diamond-like carbon (DLC) film has been studied by recording force–displacement curves with an atomic force microscope. A flat tip, a spherical tip, and some sharp tips were applied to mimic the different contact geometries. The results show that both under ambient conditions and in dry nitrogen, the DLC film can effectively reduce the adhesion force for different contact geometries. The reduction of the adhesion force was attributed to the decrease of the surface free energy and the increase of the contact angle for water. The reduction ratio of adhesion is closely related to contact geometry, the roughness of DLC film, material characteristics paired with DLC film and the environment. These factors are mutually coupled to determine the final reduction ratio. Under both conditions, the DLC film also plays a role in reducing the wear and tear when measuring the adhesion forces.