Description and types of body corrosion protection
Content
It is known that the metal surfaces of vehicles must be coated with anti-corrosion agents. The fact is that even with careful maintenance, the body is constantly influenced by external physical and chemical factors, as a result of which rust is formed. The anti-corrosion coating greatly helps to extend the life of the body and the vehicle as a whole.
What is corrosion, why does it form and why is it dangerous?
Corrosion is the destruction of a metal due to its chemical reaction with water and oxygen. In the process of movement, the unprotected surface of the body and other parts is constantly exposed to mechanical stress and comes into contact with air, which contains oxygen.
Atmospheric precipitation, in turn, contributes to the ingress of moisture on the metal, and in hard-to-reach places of the car, moisture evaporates for a long time. Iron reacts with water and oxygen to form harmful rust.
Rust is one of the most serious "diseases" of the body. Its spread leads to a weakening of the vehicle's structural structure and reduces the level of passive safety in a collision.
Most vulnerable spots
The body, due to its complex structure, rusts unevenly. The most vulnerable spots include:
- Welds. Welding cannot ensure complete tightness of the parts, so there are always microcracks in the seams. At constant humidity, it is in the places of welding that primary centers of corrosion are formed.
- Bottom, wheel arches, niches and sills. These places are constantly exposed to mud, sand and stones. When the car is moving at speed, the physical impact becomes very noticeable, so that corrosion forms quite quickly.
- Engine and exhaust system. A running engine has a high temperature, which is very different from the ambient temperature. Constant temperature fluctuations are also corrosive.
- The inner part of the body. The interior easily gets dirty and humid even after small trips.
All of these places require different protection, since the causes of corrosion are not the same.
Why additional processing of the body if it is done at the factory?
Many motorists believe that only old cars with impressive mileage are susceptible to corrosion, and new cars do not need additional anti-corrosion treatment. In reality, this is far from the case, as the manufacturer's treatment is more likely to protect the car from factory defects.
In real conditions, the car is constantly exposed to aggressive factors: high humidity, chemicals on the roads, and even acid rain.
The manufacturer rarely takes into account the influence of such conditions, moreover, the quality of the factory processing does not always have an acceptable level.
Many cars are galvanized during production, however, this measure is also not a panacea for corrosion. The thickness of the zinc layer is very small, so that various mechanical damage and vibration load easily destroy it.
Types of protection
To protect the car, many types of anti-corrosion treatment have been developed:
- Active. It is carried out using products that interact with metal and repel moisture.
- Passive. This includes barrier protection, for which different types of coatings or patches are used.
- Transforming. Includes products that help get rid of rust that has already appeared on the body.
- Complex. It implies the use of several methods at once.
Electrochemical protection is sometimes referred to a separate category.
Electrochemical method
A very effective method with which you can achieve the same high result as with galvanizing. The essence of this method lies in the peculiarities of the course of chemical reactions between metal, oxygen and water.
According to the laws of physics and chemistry, it is necessary to create a difference in electrical potentials. An element with a high potential is oxidized, and an element with a low potential is reduced.
Thus, to protect the metal from oxidation, a negative potential is imparted to it. The advantage of this method is the anti-corrosion effect even in hard-to-reach parts of the body.
Cathodic protection
Most often, electrochemical protection is carried out by the cathodic method. In this case, the metal of the body acquires a negative potential and is restored. To shift the potential, it is necessary to ensure the passage of current, which is carried out using a special device.
The corresponding electronic module can be purchased or made by hand, then installed in the passenger compartment and connected to the on-board network.
The device must be turned off periodically, since a negative effect is observed with a strong potential shift.
As an anode - an element that will have a positive potential and undergo oxidation - you can use a metal garage or grounding in an open parking lot. When the car is moving, the anode is the grounding with the road: for this, it is enough to attach a rubber strip with metal elements to the bumper. When driving, a potential difference is formed between the body and the road.
Anode protection
When using anodic protection, it is necessary to install copper, aluminum or zinc plates on the body, which will oxidize and "pull" the destruction process onto itself. As a rule, they are placed on the mountings of headlights, mud flaps, internal surfaces of sills or doors. The disadvantage of this method is the installation of plates, which still cannot cover the entire body.
Barrier methods
Corrosion often occurs at specific locations that are often in contact with water or physically damaged. Such places can simply be closed with mechanical barriers, which will significantly slow down the rate of its occurrence.
As a rule, the following are the barriers:
- Special primers and mastics, which thoroughly cover the surface of the body.
- Plastic overlays. Usually, special fenders are installed on the wheel arches, the sills and bottom of the doors are closed with body kits, plastic elements or leatherette linings are also found on the front and rear edges of the hood.
- Lamination. Application of a film made of vinyl or polyurethane. The body, covered with a film, is reliably protected from stones, various minor damages, exposure to the sun and moisture.
Usually, motorists combine several methods of barrier protection at once.
Combined corrosion protection
The combined method involves the use of several methods of combating corrosion. For example, you can use plastic overlays and the application of moisture-repellent compounds. Other car owners prefer to use cathodic protection and special primers.
Any car is inevitably prone to corrosion, and a factory coating is not always a reliable anti-corrosion agent. To extend the service life of the body, it must be comprehensively protected from destruction almost from the very beginning of the vehicle's operation.
