How to Choose Between Zinc and Aluminium Sacrificial Anodes

Sacrificial anodes are usually bare metals that are used to protect other metals from corrosion. You will find anodes in equipment that is used for underwater operations. These include boat propellers, hull fittings, rudder stocks, and other metal parts that are exposed to water. In the event of a chemical reaction, the sacrificial anode erodes and protects the rest of the equipment from corrosion damage. Zinc and aluminium are two common metals used as sacrificial anodes, but most people have a problem choosing between the two. Is there one that is superior to the other? Here are three factors that you should consider when choosing between the two metals.

Water bodies

The first thing that will determine the best anode for your use is the application of your equipment. Where will you be using it? Is it in fresh or salt water? You may have heard about the calcareous coating problem in salt water bodies and how some anodes don't hold up due to the salts. Aluminium anodes tend to perform excellently in all kinds of water bodies. You can also use them in salty water seas and lakes without worrying about calcareous coating. However, on the other hand, zinc will also perform well in salt water, but it may not be suitable for freshwater bodies. This is because, in fresh water, zinc may develop a hydroxide layer which will render it useless. This will expose your equipment to corrosion.

Anode lifespan

When you need an anode for your boat or other marine equipment, you should choose one that can last for an extended period without requiring replacement. That's because you will end up incurring enormous costs and downtime to replace an anode. Aluminium is very active in salt water, and this means that it will erode faster when exposed to marine environments. However, it lasts longer in fresh water. On the other hand, zinc is less active in salty water, and this makes it a more suitable choice for marine environments as compared to aluminium. However, it will perform poorly in fresh water.

Environmental concerns

Are you looking for a sustainable metal that will not pollute the environment? When it comes to anodes, zinc is usually associated with an element known as cadmium. Cadmium is a highly toxic element that is a by-product of zinc production. The use of zinc anodes increases the exposure of this substance to the environment. If you are looking for a sustainable metal, aluminium is your best option as it is cadmium-free.

As you can see, your best anode will be based on the where you want to use it, longevity and any sustainability concerns that you may have. Use these tips to find the best option for your application.