12:35. Metal corrosion

About 70% of cost of the car are defined by a condition of a body. And it, in turn, depends on whether the car visited accident and, the main thing, from extent of its corrosion damages.

The reasons causing the accelerated corrosion are subdivided into two groups and are connected:

 – with design or technological features of concrete models;
 – with external influences.

It is possible to carry to the first group:

 – emergence of high tension and vibrations of metal of a body;
 – existence of "pockets" in the bearing sections of bodies;
 – use of a thin metal leaf (0,7–0,8 mm);
 – use of metal with the impurity increasing corrosion speed;
 – existence of concentrates of corrosion in the form of moldings and other jewelry.

Treat external influences:

 – the sulphurous connections, carbon dioxide and chlorides which are contained in the environment;
 – the salt solutions applied to fight against ice.

Under our conditions the greatest impact is made by various salt solutions as lead to formation of conducting "bridges" between body details, as a rule, having different electric potential. It causes the most swift-flowing type of destruction of metal – electrochemical corrosion. The point is that all cars have the single-wire electrical circuitry, and, therefore, on a body currents from one consumer to another "walk".

Let's not go deep further into the theory, having left it to experts in the field of corrosion, and we will address practical questions. These results are based on use during examination of three types of the devices allowing to estimate:

 – change of thickness of "live" metal, that is not affected by corrosion;
 – metal erosion degree from the inside, in other words, degree of its loosening or destruction by oxides;
 – thickness of cosmetic layers (paint, filling) that allows to define whether there was a body under repair and attempts to hide it.

Results of expertizes which are carried out by experts allow to draw the following conclusions:

1. In the conditions of our region the speed of penetration of corrosion into metal for cars with winter operation makes – 0,2 mm a year and 0,1 mm a year for the cars which were not seeing salt.

2. Especially quickly corrosion in the zones which were exposed to body repair, and absolutely quickly develops if this repair was made with use of welding or the soldering as electrochemical couples from diverse metals are created. For buying the car, in particular the foreign car, it is essentially important. Not for nothing economical Europeans practically always sell even slightly beaten car (the truth, having received an insurance) for nothing – $1-2 thousand. Then resell for how many them in our markets, the reader, probably, knows also. But if you were lucky to find the latent defect before purchase commission, know that the actual cost of such car is 25-50% lower, than at unbeaten. It is impossible to forget that sooner or later you will sell the car, and without experts expensive purchases are done now by only very naive people.

3. Most quickly there is a process of corrosion in the cars which are operated in the winter and stored in garages especially warm, without preliminary dissolution of salts flowing water. We emphasize, not washing off, namely dissolution. Very much those who believe that, washing away a strong stream the lower part of the car, they do a good deed are mistaken. Salts are easily dissolved also without strong pressure, and here sheetings from a powerful stream quickly enough "come unstuck" from metal, sag, creating only protection illusion. In the cavities which are formed between metal and the sagged mastic corrosion develops much quicker, than on open metal.

Extremely it is not recommended to wash the car with hot water as because of different temperature expansion the sheetings which are getting warm first of all "slip" from metal, forming negative effect.

Those who believe that the sheeting is thicker, the better are not right. In total just the opposite. The main thing that in a covering there were no gaps, and therefore it needs to be updated regularly.

In conclusion – a practical advice. From two cars not that which is "younger", and on what process of destruction of metal did not get on depth more than 0,4-0,5 mm is better. In this case any processing it is impossible to prevent formation of holes in one and a half-two years. To the contrary, even the old car possessing since the beginning of operation reliable protection will serve a lot more years. Under our conditions in the foreign car it is possible to repair the engine and a running gear, but it is economically inexpedient to repair strongly rotted through body.