Impact of Nickel Interlayers on the Durability of Precious Metal Sliding Contact Systems: A Comparative Study

Sliding contacts are used across many applications where the transfer of electrical signals from a rotating part to a stationary counterpart is required. The service life of the sliding contact system is of critical importance. This study explores the influence of different nickel (Ni) interlayers between the Copper Base and the gold-cobalt (AuCo0,3) contact surfaces. Assuming chemical uniformity of the Au-Co layers, three distinct Ni interlayers (Ni-P, Ni-sulfamate, Ni-glossy) were examined not only for their direct effects on the service life, but also for their influence on the mechanical properties of the Au-Co layer. A series of tests to determine the surface's physical properties, including hardness, evaluation of wear resistance and measurement of contact resistance, were carried out for initial characterization. This is followed by application-related service life tests until system failure with a Pd-alloy MWW (Multi-Wire-Wiper) sliding contact. The test results indicate a substantial impact of the Ni layer selection on the precious metals sliding contact system's performance, indicating that selecting the appropriate Ni interlayer is critical for enhancing the longevity of these systems. This study provides beneficial insights for the design of more resilient sliding contact systems and potentially leading to improvements in performance and reliability.