Influence of different Ni coatings on the long-term behavior of ultrasonic welded EN AW 1370 cable/EN CW 004A arrestor dissimilar joints

Abstract

The increasing demand for energy-efficient vehicles requires suitable methods for cost and weight reduction. This can be achieved by the replacement of copper by aluminum, in particular for the on-board power systems. However, the complete substitution is restricted by the mechanical and physical material properties of aluminum as well as challenges in the aluminum copper interface. The challenges concern the corrosion vulnerability and the occurrence of brittle intermetallic compounds (IMC) which can negatively influence the mechanical properties and the electrical conductivity. Therefore, current investigations focus on the one hand on the realization of dissimilar aluminum copper joints by suitable joining technologies, like ultrasonic welding, and on the other hand on the assurance of a sufficient prevention against harmful corrosion effects. In cases where the joint cannot be protected against corrosion by sealing, nickel coatings can be used to protect the joint. In the present study, the influence of electroless, electroplated, and sulfamate nickel coatings was investigated regarding the long-term stability. The joints were performed as industry-related arrester connections, consisting of EN AW 1370 cables and EN CW 004A terminals. The samples were exposed to corrosive as well as electrical, thermal, and mechanical stress tests according to current standards and regulations.