An Experimental Investigation of the Contact Area Between a Glass Plane and Both Metallic and Carbon-Nano-Tube Electrical Contacts

The work presented follows an initial study into a method for the 3-dimensional (3D) scanning of an electrical contact surface, while in physical contact with a glass plane. The method allows the measurement of contact force and the associated contact area in contact with the glass. A new test apparatus is presented which allows improved control of the contact force and improved analysis of the contact area. The materials investigated include Ag and Cu contact surfaces and a multi-walled carbon nano-tube-Au composite surface. The methodology uses a confocal laser scanner with 2 mum spot size and 10 nm resolution to measure the contact surface height (Z) through the glass plane. A levelling procedure is used to ensure that the true contact region is measured, and a data grid resolution of 0.1 mum in the X,Y plane is used to identify the contact regions. The contact asperities are identified and compared with measurements using an AFM probe. The results are used to provide input data to the Greenwood-Williamson model for contact mechanics.