On the Relationship between Contact Resistance and Load Force for Electrode Materials with Rough Surfaces

Abstract

Higher contact resistance not only increases power consumption and temperature rise but also causes undesirable interconnectivity between electrode materials, which further influences the electrical lifespan and reliability of switching devices. However, relevant studies on the relationship between contact resistance and load force, and on the reduction of contact resistance by controlling the micro-structure of rough surfaces, especially for electrode materials with larger Sq (root mean square) values, are very limited. In this study, the contact resistance calculation method, based on classical Holm theory in combination with the elastic and plastic deformation, was reviewed. Then, typical curves of measured contact resistance and load force were analyzed and compared with the calculation results for smooth surfaces. Furthermore, experimental results for electrodes with bright and matt surfaces were compared. It was found that the average contact resistance of samples with matt surfaces was 0.162 mΩ for a load force of 5 N, which decreased by 18.52% compared to that of the bright surface. The standard deviation of the contact resistance greatly decreased to 0.008 mΩ for samples with matt surfaces, which indicated that the matt electrode surface could effectively produce low and stable contact resistance. In addition, the influences of the numbers and sizes of contact a-spots on the relationship between contact resistance and load force were investigated. It was found that denser asperities with smaller curvature radii for the matt surface were beneficial for lower contact resistance, even for the electrode material with larger Sq values. Finally, an empirical model of the contact resistance with error bands based on the experimental results was established and verified.

Strain‐Driven Negative Resistance Switching of Conductive Fibers with Adjustable Sensitivity for Wearable Healthcare Monitoring Systems with Near‐Zero Standby Power

“…As mentioned previously, the main sensing mechanism is based on the structure‐induced “contact resistance” by the “open and close” effects using pre‐designed cracks during the stretching and releasing cycle of the fiber. According to Holm theory, [ 42 ] for two bodies in contact, the contact resistance can be expressed using Equation () $$$$\begin{equation}{R}_c = \ \frac{\rho }{2}\sqrt {\frac{{\pi H}}{{nP}}} \end{equation}$$$$In Equation (), R c represents the contact resistance of two contacted bodies and ρ and H are the resistivity and hardness of the bodies, respectively, assuming that the two bodies are composed of identical materials. n represents the number of contacting points within the contact area (in macroscale, the contact surface is actually composed of many individual contact points).…”

Numerical Simulation and Modeling of Mechano–Electro–Thermal Behavior of Electrical Contact Using COMSOL Multiphysics

“…When a pair of contacts touch, electrical current passes with a certain electrical contact resistance. There are several factors [7] that influence the current flow and thus this resistance: contact area [8], shape [9], roughness [10], oxidation and coatings [11,12], mechanical loads [13], etc. The electrical contacts' resistance should be low and stable, since its increase leads to contact failure and very high Joule heat losses [14].…”

Simulation on electrical resistance of sliding electrical contact in pantograph-catenary system

“…Zhao S established a mathematical model of the dynamic contact resistance of the pantograph-catenary system with regard to speed, pressure and other parameters [8]. Zhang C considered the influence of roughness and studied the relationships between contact resistance and pressure [9]. Liu F constructed a pantograph simulation model and obtained the change trend of pantograph contact resistance during operation [10].…”