You’ve probably heard that stainless steel and aluminum don’t play well together. However, you may have also seen them used together in various applications, such as a stainless steel sink with an aluminum tap. So, does stainless steel react with aluminum?
Stainless steel reacts with aluminum in a process called galvanic corrosion. This corrosion occurs when two dissimilar metals are in contact with each other in the presence of an electrolyte, like salt water. When this happens, electricity flows between the two metals, causing corrosion.
This article will walk you through galvanic corrosion, how it can happen between stainless steel and aluminum, and how to prevent it. Let’s get started!
What Is Galvanic Corrosion?
Galvanic corrosion is the transfer of electrons from one metal to another. This happens when you have an anode, cathode, and electrolyte in contact with each other. The positive metal wants to eliminate its electrons, while the negative metal wants to receive them.
In this case, aluminum is the anode, and stainless steel is the cathode. And it’s also worth noting that rust occurs on the anode or the aluminum. This is because aluminum has a more negative electrochemical potential than stainless steel.
One of the most common electrolytes is salt water, explaining why you often see galvanic corrosion in coastal areas. However, this can also happen in other environments, such as when two different metals are in contact with each other and there is a lot of moisture content in the air.
In the worst-case scenario, galvanic corrosion can cause a complete degradation of the metal, leading to structural failure.
See also: Why Is My Brand New Stainless Steel Sink Rusting?
How to Prevent Galvanic Corrosion
The best way to prevent galvanic corrosion is to avoid contact between aluminum and stainless steel at all costs. This can be done using a barrier, like paint or a coating.
If you’re looking for a more long-term solution, you can use a stainless steel sleeve. This sleeve is a tube that goes over the aluminum to prevent contact with the stainless steel. This method works well for piping and other applications where the two metals need to be close to each other.
You can also use a cathodic protection system. This system uses an electric current to prevent corrosion and is often used in saltwater environments, but it can also be used in other settings.
However, cathode protection will not work for all applications. A better solution is to coat the anode with a different metal. For example, magnesium is more active than aluminum and will corrode before aluminum does, protecting the aluminum from corrosion.
Whatever you do, ensure you take action to prevent galvanic corrosion. If left unchecked, it can cause serious damage to your metal objects.
What Influences Galvanic Corrosion?
Just like everything else in life, many factors can influence the rate of galvanic corrosion. These include:
The Type of Metal
Some metals are more active than others, meaning they will corrode sooner than less active metals. The most active metal is magnesium, followed by zinc and aluminum. The least active metals are noble metals, such as gold and silver.
The Presence of an Electrolyte
An electrolyte is needed to complete the circuit between the two metals for galvanic corrosion to happen. The most common electrolyte is saltwater, but it can also be moisture. This means that galvanic corrosion is more likely to happen in coastal areas.
The Concentration of the Electrolyte
The concentration of the electrolyte can also influence the rate of corrosion. The higher the concentration of electrolytes, the faster the corrosion will occur. This explains why you often see galvanic corrosion in coastal environments.
The temperature can also influence the rate of corrosion. In general, high temperatures will accelerate the rate of metal decay. This is because the higher the temperature, the more active the metals become. If you live in an area with a warm climate, it could explain the high rate of metal corrosion.
The pH Level
The pH level can also play a role in galvanic corrosion. The lower the pH level (or the more acidic it is), the greater the chance of decay. This is because acidic environments are more corrosive than neutral or alkaline environments.
The Surface Area of the Metals
The surface area of the metals can also influence the rate of corrosion. A larger surface area increases the chances of corrosion. This is why galvanic corrosion is often seen on metal objects with a large surface area, such as pipelines.
The time that the two metals are in contact with each other can also influence the corrosion rate. The longer the exposure, the greater the chance of corrosion. This is why galvanic corrosion is often seen in metal objects that are in contact with each other for long periods, like sink fixtures.
How to Test for Galvanic Corrosion
There are various ways to test for galvanic corrosion:
- The most common method is using a voltmeter. This device measures the electric potential between two metals. If there is a potential difference, it means that corrosion may occur.
- Using a piece of aluminum foil is another effective method. Place the foil between the two metals and check for discoloration. If the foil turns brown or black, it means that corrosion is happening.
- A solution of copper sulfate can also indicate galvanic corrosion. Apply the solution to the area where the two metals meet. If there is a blue color change, it means that corrosion occurs.
Galvanic corrosion can be a serious problem, but it’s also preventable. You can avoid this corrosion and keep your metals in good condition by taking the necessary precautions, which I will discuss in the next section.
How to Use Stainless Steel and Aluminum Together
Stainless steel and aluminum can actually make a great team. While they both have unique benefits, they can complement each other quite well. For example, stainless steel is known for its durability and resistance to corrosion. On the other hand, aluminum is known for being lightweight and easy to work with.
When these two metals are combined, they can create a strong and lightweight material. This makes it ideal for various applications, from automotive parts to kitchen appliances.
However, there are a few things to remember when combining stainless steel and aluminum.
- Choose the right grade of stainless steel. Not all grades of stainless steel are created equal, and some are more resistant to corrosion than others. The most common grades of stainless steel are 304 and 316.
- Make sure you buy the right grade of aluminum. The most common grades of aluminum are 1100 and 5052, and it is also important to choose the right thickness for the application.
- Take care and maintain the material. Both stainless steel and aluminum are susceptible to corrosion if they’re not properly cared for. Make sure you clean the material regularly and remove any dirt or debris that could cause corrosion.
When it comes to choosing between stainless steel and aluminum, there is no clear winner. It really depends on the application and what your needs and preferences are.
However, combining these two metals is a great option if you’re looking for a strong, lightweight, and corrosion-resistant material.
So, does stainless steel react with aluminum? In most cases, yes. This is especially true if you live in a coastal area with lots of humidity and salt content in the air. If you’re concerned about this type of corrosion, use high-quality metals, and place a solid barrier between them to prevent direct contact.
If you’re concerned about galvanic corrosion in your kitchen, don’t worry! You can still use stainless steel and aluminum items if you take the necessary precautions. Just avoid allowing damp to settle on the metal for extended periods.