Myths and legends

Why doesn t aluminum cookware react with water?

The basis of aluminum cookware, both with non-stick coating and without coating, is ALUMINUM – a chemical element of group III of the periodic table of D.I. Mendeleev, occupying 3rd place in abundance after oxygen and silicon in the earth’s crust (about 9%). Contrary to the prejudices of many ordinary people, groundlessly supported by media reports about the dangers of aluminum, this metal is safe and the most “convenient” for the production of cookware with a non-stick coating.Aluminum is found in significant quantities in water, air, and soil. It is also present in a normally functioning human body.

  • practically does not react with concentrated and diluted NITRIC ACID;
  • interacts with difficulty with concentrated and dilute SULFURIC ACID;
  • does not dissolve in ORTHOPHOSPHORIC ACID.

The beneficial natural properties of aluminum today find application in various spheres of human activity:

NATURAL PROPERTIES OF ALUMINUM

  • Proven high corrosion resistance of aluminum

The main characteristic of aluminum oxide, as described above, is constant oxidation when interacting with oxygen and, as a result, the formation of a thin oxide film on the surface of aluminum, which serves as “armor” and protects the metal from acids.

  • Preservation of vitamins and microelements

Thanks to the thinnest oxide film, aluminum has a valuable property – it does not destroy vitamins and valuable microelements in food products. That is why equipment for the medical, oil-processing, sugar, confectionery and brewing industries is made from it.

  • Active use of aluminum in packaging production

The safety of this metal is also supported by its active use in the packaging industry (yogurt, chocolate, medicines, drinks). Aluminum is impervious to ultraviolet rays, which destroy many foods. It is impermeable to gases, odors, liquids and dust. It is used in the production of caps, cans for soft and low-alcohol drinks and beer, and packaging for various products – from yogurt to medicines.

WHY IS ALUMINUM IDEAL FOR COOKWARE PRODUCTION?

STILL Recommended

Rules for caring for a non-stick frying pan

We all know what a frying pan is and how to use it. But how to preserve the product so that the frying pan serves you for a long time? Proper use of your frying pan is the first step in caring for it properly. In order for non-stick cookware to serve you faithfully for many years, you need to constantly adhere to a few simple rules when using them.

Internal coating: ceramic or non-stick?

SCOVO, caring about its consumers and due to the dominance of the Internet with unverified and incorrect information of a speculative nature around the topic of non-stick cookware in general and non-stick coatings in particular, decided to refute the existing myths of the advantages and disadvantages of both ceramic and non-stick coatings (or Teflon).

Cookware for professional use

No kitchen, especially a professional one, would be complete without cookware and accessories. A colander, a slotted spoon, and spoons are the cook’s daily tools. Therefore, they must be lightweight, easy to use and, importantly, durable. All these requirements are met by aluminum cookware from the SCOVO brand, the range of which is presented in this article.

Aluminum is in demand in various industrial fields because it has good strength, reliability, resistance to wear and to many negative environmental factors. But in addition to all the advantages, such a material has a competitive advantage – aluminum is resistant to corrosion even in various difficult conditions of use, when exposed to many aggressive substances. Why does aluminum not corrode? Let’s look at it in more detail in this article.

Why doesn’t aluminum rust?

The structure of the metal is built in such a way that it is able to independently protect itself from corrosion. When exposed to air, free aluminum atoms form an oxide film. It protects the material from destructive processes.

The natural oxide layer has a small thickness (up to 3 nm). But if you create certain conditions, then this film will not deteriorate for many years and will become an excellent protection against negative external influences.

But as soon as the integrity of the oxide layer is compromised, the process of metal corrosion will immediately begin. Over time, it will lose its original properties.

Destruction always starts from the surface. After this, corrosion penetrates further into the metal structure at a rate that depends on the alloy and various negative external influences. First, metal products become matte or change their shade, after which characteristic spots and dots appear. And as a result of further contact with a hazardous environment, corrosion products appear, which only accelerate the destructive process. Such aggressive external factors include temperature conditions, stray currents, and proximity to various metals. The rate of destruction is also affected by the chemical composition of the alloy, the structure of the metal and internal stresses.

What are the causes of corrosion?

The material quickly deteriorates if the oxide film has been damaged.

And various external factors only accelerate this process:

  1. Contact with acid or alkali. Corrosion of aluminum in acidic environments is quite common. Nitric or sulfuric acid quickly leads to the destruction of aluminum, giving a very strong reaction. Even dilute acid promotes the formation of irreversible processes that cannot be weakened by the addition of any inhibitors. Organic acids and their salts have a negative effect.
  2. Mechanical factor. These are impacts, friction, high wear – everything that leads to the formation of chips and scratches on the top layer. All formed defects will become a place for the free flow of moisture to the metal, and, accordingly, the start of corrosion destruction.
  3. Fuel breakdown products. If aluminum products are constantly in contact with the breakdown products of liquid fuel, this will lead to the rapid destruction of the natural protection of the material. Acids and aldehydes found in these products cause rust. Therefore, in megacities, aluminum products are more susceptible to corrosion damage.
  4. Chemical reaction. The most serious metal destroyers are fluorine, potassium, sodium, chlorine and bromine. Upon contact with these elements, a strong chemical reaction begins, which ultimately contributes to the oxidation and destruction of the metal.
  5. Construction mixtures. Solutions that contain lime and cement are extremely aggressive environments for aluminum. Concrete immediately starts corrosion processes.

But there are also factors that can slow down and even stop the process of corrosion destruction of aluminum; let’s consider them in more detail:

  1. Purity of the alloy. In the production of responsible and important equipment and loaded structures, as a rule, high-purity metal with a minimum amount of impurities is used. According to statistics, an alloy containing 90% pure metal undergoes corrosion processes 80 times faster than an alloy consisting of 99% aluminum.
  2. The environment in which aluminum is located. It is important to consider the composition of the alloy and the further area of ​​use. For example, a high percentage of copper in the composition can reduce the likelihood of rapid destruction during prolonged exposure to seawater. It is also important to exclude unfavorable proximity, which may contribute to the formation of cathode-anode bonding.
  3. pH value of the medium. The oxide layer forms naturally when the pH of the environment is in the range from 3 to 9. This is the optimal acid-base balance at which corrosion processes cannot develop.
  4. The presence of an additional protective layer. To increase the anti-corrosion qualities of the natural layer, special protective paints or polymer coatings are often used. But metal anodization has become more widespread.

After anodizing, a durable and thick protective coating (up to 25 nm) is formed, which is much more difficult to damage. Therefore, anodized aluminum products have a higher margin of strength and durability.

To improve the protective layer, an electrolysis process is used in which aluminum acts as the anode and other materials as the cathode. The entire system is loaded into a container with electrolyte, after which an electric current of a certain strength is passed through it.

During the anodizing process, the metal not only becomes stronger, more reliable, and more resistant to destructive external factors, but also more beautiful, since it can be additionally painted in different colors, which increases its aesthetic value. The anode layer does not require special maintenance, retains its protective and decorative qualities for a long time, and has excellent anti-vandal properties. Therefore, anodized aluminum products have an impressive range of applications, especially when it is necessary to use structures in difficult outdoor conditions.

Production of lighting equipment Alumpark offers high-quality aluminum anodized lighting poles. They are excellent for use in different regions and are not afraid of the negative influence of external factors. All products have a long warranty.

Why does aluminum deteriorate in air?

Corrosion destruction is largely influenced by the degree of aggressiveness of the environment:

  • rural areas, as a rule, have a small percentage of hazardous impurities, an average level of humidity, and therefore are not so aggressive for aluminum products;
  • coastal regions, in this case there is an increased level of humidity, and aluminum is also negatively affected by sea salts, which are also an important factor for the occurrence of corrosive destructive processes;
  • urban areas, where a large number of decay products of fuel, sulfur, and carbon oxides predominate;
  • industrial areas in which there are large amounts of sulfur, carbon and various acids, and they are very dangerous for the metal.

The following negative factors increase the rate of development of the corrosion process in air:

  1. Humidity indicator. If there is periodic contact with moisture, and in general the humidity level is normal, then this will not affect the metal products in any way. But if there is high humidity (more than 80%), this will increase the rate of aluminum destruction many times over.
  2. Composition of the surrounding atmosphere. The more hazardous impurities in the atmospheric air, the higher the likelihood that aluminum will begin to rust. The most aggressive are sulfates, which are often present in industrial areas.
  3. Amount of electrolytes. The development of corrosion in air depends on the so-called duration of humidification and the chemical composition of the electrolytes located on the surface. If the ambient humidity level is about 80%, and the temperature on the surface is above 0°, then under these conditions condensed moisture appears, which leads to the gradual destruction of the natural oxide layer.
  4. The climatic conditions of the region, where not only the level of humidity is important, but also the duration, intensity of precipitation, average temperature, and the number of sunny days per year.

But if you carry out anodizing, you can increase the service life and protect it from negative external influences.

How does water affect aluminum?

The main negative impact is caused by chlorides and heavy metal ions found in water. Chloride ions are able to penetrate natural oxide films because they are tiny in size and can replace oxygen atoms. This leads to a deterioration in the durability of the protective coating and the appearance of corrosion.

In fresh water, metal is mainly subject to pitting corrosion. But if you regularly dry aluminum products, then, as a rule, the risk of serious rust is minimal. That is why aluminum pots, kettles, frying pans, spoons and mugs are so often used, which serve without problems for decades.

The likelihood of destruction increases if the water is stagnant, as it contains more dangerous impurities. It is especially harmful if aluminum is in contact with water for a long period of time.

It’s a different matter when aluminum is in sea water. It contains a large amount of dissolved inorganic salts, most of which are chlorides. But the pH of sea water is within the permissible limit for the metal of 8,2. This value does not exceed the protection standard for the natural oxide film. This explains the good resistance of the metal to sea water. But aluminum-magnesium alloys, where the magnesium content is no more than 2,5%, are less susceptible to the negative effects of salt water. This alloy is actively used in shipbuilding.

To protect aluminum products from aggressive sea or fresh water, various methods are used:

  1. Application of protective coatings such as paints or varnishes. They create a reliable barrier between water and aluminum, preventing contact and, accordingly, interaction with hazardous chemicals. But these coatings, as a rule, wear out quickly and therefore require periodic updating.
  2. Application of anti-corrosion coatings that contain zinc or other metals. This option prevents negative external influences, while it is more long-term, but the treated surface requires specialized care.
  3. Anodizing. This is the most effective way to protect aluminum in seawater as it creates a hard oxide film that has excellent corrosion resistance, does not degrade over time, and does not require any special maintenance.

An important aspect of protecting aluminum products from corrosion in seawater is the correct selection of the alloy, regular checking of the integrity of the surface, and its proper maintenance.

In many ways, corrosion processes in sea water can be enhanced by all kinds of pollution, increased temperature and biological effects.

Aluminum has a natural protective film. But when exposed to many external factors – be it high humidity, increased temperature or dangerous chemicals – the protective layer is destroyed. Therefore, various methods are used that improve the durability of the metal. This is the application of different compositions. But the most effective way is anodizing. Anodized products are the most reliable and durable, which is why they have such a wide range of applications.

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