Sacrificial Corrosion, Sacrificial Coating, Cathodic Protection And Many More

You might have heard that In life you need to sacrifice something to achieve another. And We see that to some extent it is correct. You sacrifice many things in life without knowing it. All of it to achieve something. Whether you are sacrificing the taste of cold drink for cooling it with ice, Or you sacrifice your precious and cozy sleep for completing that assignment that has been due tomorrow and you spent the last week procrastinating about it. Well… You get the Idea. Sacrifices are common and If they are so common, There must be some in Chemistery too. And Today We’ll Talk About It. Well…. That’s Why we’re here. As long as It is related to Corrosion and Chemistery You’ll find it on our page, If not now then maybe in the future.

We know that many metals corrode. Whether It’s your silver ornaments turning grey and loosing the luster, or that’s the battery holder pins of your favourite toys rusting and you realize, Wait a minute… This battery holder can no longer hold the dry cells as the springy thing broke due to rusting. Sometimes it’s not your personal loss, but a loss for many people. Imagine that an underground pipe corrodes that supplies water to a very large building. If it remains unnoticed, It can weaken up the entire foundation and base of the building and in extreme cases, Boom! The building can just fall. So what can one do to prevent this. Aluminium doesn’t corrode but is not strong enough to be used in making pipes that have to go under the ground. AND THAT’S WHERE SACRIFICIAL PROTECTION COMES IN.

Before knowing more about sacrificial protection, sacrificial coating or anything related, Try to make a wild guess. And Remember that Cathodic protection and Sacrificial protectio are same things, So if we use the word “Cathodic Protection”, Don’t freak out.

By just reading the word “Sacrifice” we know that something is sacrificed here. In sacrificial protection, just like in life, One thing is sacrificed to gain other. But WHAT and HOW ? Let’s just say that you have to protect a steel object from rusting. In cathodic protection, A steel object ( Or any other metal that has to be protected ) is made cathode and another metal which is More Active than the steel object is made anode. This Anode is also called “Sacrificial Anode”. We will discuss it later. The sacrificial anode is more active than the steel object or cathode and oxidizes it self. As we know that corrosion is an oxidizing process. The Anode oxidizes and prevents the Cathode from oxidizing/corroding. In this way The Anode is sacrificed and the Cathode is protected (Thus the name “Sacrificial Anode”).

One other term that you might’ve heard is “Sacrificial Coating”. Now What is This. Remember in last paragraph I told you about Connecting More Active metal to the steel object. Sometimes Instead of connecting the metal externally, It is coated over the steel object. Usually Zinc, Magnesium or Aluminium is used as Sacrificial Coating. Here I’ll only tell you about the Zinc coating method. This process is also called galvanizing. When there is moisture, The Zn turns in to Zn² ions and the water from moisture turn into negative hydroxyl ions. The Zn is oxidized and protexts steel from corroding.

Essentially, this method hijacks the corrosion process and steers it in a direction that won’t be harmful to the asset the coating is meant to protect.

And Remember that sacrificial coating, Sacrificial protection, Sacrificial coating and Cathodic Protection are the same things.