Electrical treatment of thermal sprayed copper layers to improve the electrical conductivity

A new method to enhance the electrical conductivity of thermal sprayed copper layers has been discovered and investigated. The aim is to reduce the electrical resistance of the copper layers by applying a high electrical current to the layer. Two different types of electrical treatments were conducted: a short-time treatment, in which a high current (up to 1000 A/mm²) is applied for less than 1 second, and a long-time treatment, during which the sample was heated up to approximately 580 °C using the direct heating of the layer by electric current.
The main advantage of the short-term treatment is that it results in an instantaneous improvement in resistance without affecting the surrounding material. The effectiveness of the methods has been proven through an extensive study. The influence of the individual process parameters as well as the influence of the atmosphere on the terminal resistance were determined. Both the metallurgical conditions causing high resistance of the as-deposited layer, as well as the processes leading to a change of the resistance during the electrical treatment, were investigated. This method was developed for the optimisation of a multi-material part, in which the insulated conductive layer is embedded in aluminium by wire arc additive manufacturing. Furthermore, the corresponding effects of both the WAAM process as well as standard aluminium heat treatment were investigated and taken into consideration.