Tag: Corrosion

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Passivation of Aluminum and Stainless Steel: Should You Do It?

Large Steel Factory Warehouse

Why should you passivate aluminum and stainless steel?

  1. What is passivation?
  2. How does the passivation process work?
  3. When should you passivate your metal alloys?

 

Corrosion has long been the enemy of metals and their subsequent alloys. Just ask your local stainless steel supplier, and they will definitely tell you that dealing with corrosion often becomes a headache. This is especially true when certain building materials aren’t handled or treated properly. Thanks to corrosion and rust specifically, the durability of products and structures can become significantly compromised after a number of years if not within 1 or 2.

Thanks to the development of modern metal alloys such as aluminum and stainless steel, the construction industry’s struggle against corrosion became easier to deal with. This is due to the interesting ability of aluminum and stainless to undergo the process of ‘passivation’. What does that word even mean? Should you do it? and what can it entail for you and your construction endeavors?

 

What is passivation?

What Is Passivation

Passivation is a chemical process wherein an extra outer layer of protection against corrosion is added to or formed on a given material’s surface. It occurs naturally in aluminum and stainless steel which is why they have been so useful for the construction and manufacturing industries since their conception.

The fascinating part about passivation is that metallurgists have found ways to boost, accelerate, and even elevate this process in metal alloys so that they are even more resistant to corrosion than usual. Technically speaking, passivation is a form of corrosion. This is because the metal reacts with its environment to form a chemically inert surface. The thing is, this form of corrosive surface will help reduce, if not nearly eliminate, any further corrosion that could potentially happen.

 

How does the passivation process work?

Before going into the specifics, it is important to note that the process of passivation is not the same for stainless steel and aluminum. In fact, passivation is more associated with stainless steel than aluminum, so it is best to distinguish between the two.

 

Stainless steel passivation

Stainless steel has a natural form of corrosion resistance thanks to a very thin (about 5 nanometers) layer of oxide on the steel’s surface. This layer forms thanks to the chromium component of stainless steel, and for it to form properly, there needs to be at least 10.5%  chromium in the alloy. The oxide layer is also referred to as a ‘passive layer’ because it renders the surface electrochemically passive in the presence of corrosion-inducing elements.

It is important to point out that while stainless steel has a natural resistance to corrosion, not every alloy is impervious to rust. It is not surprising for small instances of rust to appear on a stainless steel surface because foreign matter can make its way and embed itself to a given metal’s surface. This makes it possible for water molecules to oxidize the iron component. This kind of corrosion is referred to as ‘roughing’, and certain grades of metal alloys are more susceptible to it than others.

In order to manually passivate stainless steel, the material must be thoroughly cleaned to ensure that no contamination can happen. After cleaning, the metal goes through a passivating acidic bath that meets the material’s temperature and chemical requirements. It is then rinsed with water and dried. Through this process, the exogenous iron is removed and a passive oxide layer is created to further inhibit the formulation of rust.

 

Aluminum Passivation

Aluminum, just like stainless steel, also undergoes a natural process of oxidation that forms a thin, protective surface layer of aluminum oxide. Again, just like with stainless steel, not every aluminum alloy does a good job of forming the said oxide layer for the same reasons stated above. Extra protective measures might be required for certain grades of aluminum.

 

When should you passivate your metal alloys?

Metallic Pipes On Warehouse, Rows Of Metal Pipes On Industrial Warehouse. Industrial Interior,

When considering the circumstances in which passivating your stainless steel or aluminum is a good idea, there are two main benefits to think about. You already know about the first one, anti-corrosion, but the lesser-known benefit of passivation is purity. Both of these go hand-in-hand because dirt and impurities are one of the causes of corrosion.

As a general rule of thumb, you should consider passivation for your metal alloys if you need extra protection from the elements. This is especially true for your outdoor structures and products that experience the full brunt of the weather. It also can not be stressed enough that different grades of metal alloys provide different levels of corrosion resistance. If the metal you are using is inherently weak to corrosion, then passivating it should be your next best option.

 

Key Takeaway

The passivation of metals is a useful process that can be either organic or engineered. Only the best local stainless steel suppliers around would know that manually passivating stainless steel and/or aluminum is a good way to maintain and protect your structures and commodities.

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How to Protect your Stainless Steel from Rust

How To Protect Your Stainless Steel From Rust

How do you protect stainless steel from rust?

  1. Use Phosphoric and Acetic acid to remove rust on industrial-grade stainless steel
  2. Use baking soda and water to remove rust on stainless steel products
  3. Using protective coating and metal paint provides a barrier from rust
  4. Lubrication is great for moving stainless steel parts
  5. Regular cleaning and maintenance at home is effective in preventing rust

 

Wear and tear is a natural occurrence for almost anything tangible, especially for different kinds of metals. For metal, the most common form of deterioration comes in the form of rust, which is a form of iron oxide that causes corrosion. Rust tends to happen in a variety of locations, and to every type of metal. While stainless steel is a type of metal highly resistant to forms of corrosion, it can still be affected by rust without proper maintenance.

This can be a challenge, especially for your nearby stainless steel supplier in Metro Manila, as they would have to make sure on a daily basis that their stocks are not affected by rust or any forms of corrosion. The best way to combat rust is by finding the right solution on removing them if they occur and creating preventive measures to protect your stainless steel.

 

How to Remove Rust

How To Remove Rust

When rust occurs on the surface of stainless steel, that means that the protective chromium oxide layer has corroded. This means that you would need to immediately fix this surface, as rust can weaken steel to the point of brittleness and disuse. Rust can be caused by a number of substances present near the area, including, acid, cleaning agents, or simply prolonged exposure to salt water and warm air.

Some of the best ways to remove rust on your stainless steel surface are by using either Phosphoric or Acetic Acid. These two types of acid can cause iron oxide to dissolve on the surface, without compromising the integrity of the stainless steel itself. It can take a significant amount of time for the acid to do their work, but rust will fully be removed once the process has been accomplished. After exposing your stainless steel surfaces with acid, it is best to clean them using distilled deionized water.

Another method that you can use for stainless steel products in your home is by using a mixture of 2 cups of water and 1 tablespoon of baking soda. After creating the mixture, rub it on the rusted surface using a toothbrush or sponge and wipe the surface with a paper towel or cloth. If successful, you will be able to see the rust come off, while the product remains undamaged.

 

How to Protect Against Rust

How To Protect Against Rust

There are many ways to protect your stainless steel against rust, and some of these methods require a set of substances and tools to ensure that iron oxide would not be able to damage the stainless steel surface. Before establishing the right preventive measure to use to protect against rust, the first thing you need to determine is if the stainless steel is for industrial or home use. Protective measures in industrial-grade stainless steel can sometimes not apply to home methods, as your stainless steel supplier in Metro Manila would use these measures to ensure that they deliver quality products.

For industrial-grade stainless steel, the best way to prevent rust is by applying special protective coatings that would shield iron oxide away from the surface. These protective coatings are easy to apply and are usually water or oil-based, making it easy to clean, maintain, and apply again if needed. Metal paint is another protective measure you can use for industrial stainless steel, as it also forms a barrier against rust, while also providing a smooth and clean surface. However, one of the main issues of using metal paint is that it can chip off easily after a certain period of time, which means that it the stainless steel surface must be regularly re-coated with paint.

Lubrication and galvanized steel are also industry-standard practices that protect stainless steel from rust. Lubrication is mostly used for moving parts, bearings, and joints, and ensure that they are kept in good working order. Galvanized steel, meanwhile, provides an additional metal layer that strengthens the metal, and protects it from rust. However, galvanization is a delicate process that requires trained personnel to accomplish.

To prevent rust from affecting your stainless steel products at home, you would need to keep them constantly cleaned and polished using non-acidic solutions in order to keep them away from rust. Alkaline water is also a good cleaning solution, as they do not contain any harmful elements that can cause rust to occur on the surface. For the right tools, stainless steel pads are the best polishing tools to keep your surface clean and well-maintained.

 

Key Takeaway

Rust can happen to any kind of metal, including stainless steel. This is why it is best to establish preventive measures that will help protect your stainless steel surface from rust and corrosion. By using these handy and effective protective and preventive, measures, you can guarantee that you would be able to avoid rust from happening to your stainless steel.

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Stainless Steel Philippines: Types of Corrosion

Stainless Steel Philippines Types Of Corrosion

What are the different types of corrosion?

  1. General Attack Corrosion
  2. Galvanic Corrosion
  3. Localized Corrosion
  4. Environmental Cracking
  5. High-Temperature Corrosion

 

Metal and stainless steel in the Philippines are widely used as a primary material for many industries. They’re tough, readily available, and can be used for various applications. Though metals aren’t indestructible, they have one major weakness. Corrosion may be caused by many different conditions and factors, let’s take a look at a few different types of corrosion:

 

General Attack Corrosion

This is the most common type of corrosion; it is also commonly known as uniform corrosion. It is considered to be an even attack of oxidation across the surface of a metal material. This form of corrosion is usually easy to determine because it is relatively simple to replicate and reproduce its effects with consistency. Usually, causes of this form of corrosion are due to chemical exposition or from an electrochemical reaction.

From this point, general attack corrosion will render the full deterioration of the metal to the point of structural failure. As mentioned earlier, it’s the most common type of corrosion, which correlates to this type of corrosion accounting for the greatest amount of metal destruction via corrosion. Since it’s common, it isn’t difficult to prevent and predict. Oftentimes, a metal that succumbs to this type of corrosion is still manageable and even preventable.

 

Galvanic Corrosion

Galvanic Corrosion

Galvanic corrosion, often times called dissimilar metal corrosion happens when two dissimilar metals are in contact with one another and in the presence of an electrolyte. This usually happens at metal structural locations such as joints or weld spots. To know how this type of corrosion occurs involves taking a deeper look at metals from a molecular level.

Three conditions must be met in order for this type of corrosion to occur. First, the metals in contact must be electrochemically different. Second, the metals in contact must be electrically connected. Third, the metals must be exposed to an electrolyte. When these conditions are met, one metal starts giving its electrons to the other metal or it becomes an anode, while the other receives the electrons or becomes a cathode.

In Galvanic corrosion, the anode will begin to rapidly rust with the cathode will become more resistant to corrosion. A common example of this is when copper and steel are linked together and suddenly become exposed to salt water.

 

Localized Corrosion

Under localized corrosion, we have three types: pitting, crevice, and filiform corrosion. These types of corrosion target a specific area in a metal’s structure.

  • Pitting Corrosion – is one of the most difficult types of corrosion to spot. It happens when a cavity is formed in the metal. What happens in the cavity is that the exposed area experiences a loss in electrons, the anodic area then becomes more susceptible to a localized form of galvanic corrosion. This cavity will weaken the structure of the metal from within, leading to potential failure.

 

  • Crevice Corrosion – crevice corrosion is similar to pitting corrosion but it doesn’t involve any electron loss. This type of corrosion happens when a cavity, small hole, or crevice in a metal becomes exposed to a stagnant microenvironment. Because of the acidic environment or the exhaustion of oxygen in a crevice, this will lead to corrosion.

 

  • Filiform Corrosion – One of the subtlest corrosions that can slip under the guise of many, filiform corrosion is a form of corrosion that happens under any form of coating. Common instances that because filiform corrosion is when a coating breach occurs and water slips in between the metal and its coating. This form of corrosion spreads underneath paint, epoxy, and many other forms of coating to cause structural weakness.

 

Environmental Cracking

Environmental Cracking

Environmental cracking is a common form of corrosion that occurs to metals exposed to various environmental conditions. Oxidation, temperature change, and chemical exposure are a few factors that contribute to various structural damages such as stress corrosion cracking, metal embrittlement, corrosion fatigue, and hydrogen induced cracking.

 

High-Temperature Corrosion

Often caused by high-temperature oxidation and carbonization, high-temperature corrosion typically happens in vehicle’s turbochargers, diesel engines, and exhaust pipes. This happens due to the fuels used in these types of machines; during combustion, various compounds attach themselves to the metal and quickly corrode the surface. At times, even stainless steel may rust due to high-temperature corrosion.

In the Philippines, stainless steel products that are exposed to high-temperature corrosion usually don’t mean that structural integrity will be compromised. Typically, in older engines, you may notice that the exhaust side of a turbocharger will always be more rusted compared to the intake side, but it still works well.

 

Key Takeaway

Knowing the different types of corrosion can help you determine whether your metal structure, parts, or components can be saved and how they can be remedied. With this knowledge, you can somehow pinpoint the causes of corrosion and prevent them from happening. If you want high-quality stainless steel that can combat the harshest effects of corrosion, click here to learn more about One Sky Philippines.