Development of Al-Zn-Cu Alloy for Low Voltage Aluminum Sacrificial Anode

In general, a conventional aluminum anode for seawater service is Aluminum-Zinc-Indium (Al-Zn-In) alloys grade. This type of alloy offers high efficiency and high potential protection in a seawater environment. Nevertheless, there is a limitation for this alloy anode. High protection potential increases the possibility for hydrogen embrittlement in high-strength steel. Therefore, a new Al anode to produce a low voltage properties is being developed. Copper addition as an alloying element reduces the potential protection of aluminum anode. Based on polarization result, the copper addition could reduce the corrosion resistance of aluminum. Furthermore, result from the metallographic examination showed that higher copper content has a higher precipitation in the grain boundary of aluminum. This precipitate in aluminum reduced the protection of passive film and increase the corrosion rate of Al-Zn-Cu alloy as a new sacrificial alloy candidate.