Effect of Contact Aid Compounds on the Performance of Bolted Aluminum-to-Aluminum Joints Under Current Cycling Conditions

A number of contact aid compounds most commonly used for aluminum-to-aluminum connectors and conductors were evaluated on the basis of their effect on the performance and stability of a bolted joint under current cycling conditions. The results show that a significant difference exists in the effect that some of the contact aids exert on the performance of the bolted joints under current cycling conditions. This difference manifests itself in higher contact resistance and rapid overheating of a joint during cycling. The observed difference was associated with the shear strength of the compound film and also with the properties of the additives such as metallic particles present in these compounds.