Electrical Resistance Model of a Bilayer-Coated Spherical Contact

A finite-element analysis was used to investigate the elastic contact of a bilayered coated sphere compressed by a rigid flat, under the normal loading and “slip” contact condition. A bilayered coating consisting of a hard outer layer and a soft interlayer relative to the substrate was studied. An electrical analysis was performed on the deformed coated sphere to investigate the effect of the thickness of both the hard and soft coatings and their material properties on the electrical contact resistance (ECR). It was found that for any given load, under fully elastic contact, proper material and thickness of the soft interlayer can increase the contact area by up to 35% and reduce the electrical resistance by up to 75%, compared to a reference case without the soft interlayer. Increasing the outer hard coating thickness increases the ECR. The increase in the contact area was found to have a secondary effect on the reduction of the contact resistance compared to the effect of the material’s conductivity.