Analysis Of The Causes Of Aging In Bimetallic Terminal Block Materials

bimetal terminal lug is made of copper and aluminum through friction welding or explosive welding. The potential difference between these two materials in the electrochemical sequence is approximately 0.7 volts. When moisture or electrolyte is present on the terminal surface, a galvanic cell reaction occurs. Aluminum acts as the anode and undergoes an oxidation reaction, gradually transforming into alumina powder. bimetallic lugs price In coastal areas or chemical environments, salt spray and acidic gases in the air accelerate this corrosion process, and white or gray corrosion products will appear at the contact interface.

Power system load fluctuations cause repeated temperature rises and falls at the terminals. The coefficient of thermal expansion of copper is 16.5 × 10⁻⁶/℃, and that of aluminum is 23.1 × 10⁻⁶/℃. This difference in expansion generates shear stress at the bonding interface during temperature changes. bimetallic lugs price list. After thousands of thermal cycles, microcracks may appear at the weld interface. The increased contact resistance at these cracks further exacerbates heating. This positive feedback mechanism causes the conductivity of the terminal to decline at an accelerated rate.