11.22.3. Anticorrosive protection of a body
At daily operation of the car the paint and varnish and anticorrosive covering of a body is influenced by hostile environment: deicing reagents (during the winter period of time), sand, small stones, vibration and temperature drops which cause emergence of microcracks in a body sheeting through which water and oxygen get to a metal surface. As a result of impact on a body of hostile environment process of oxidation of metal (corrosion) which leads to loss of prochnostny properties by it begins, and existence in water of a large amount of salts and acids only accelerates oxidation process.
Hollow profiles of a body, the bottom, the lower parts of doors and racks, and also connections of details of a body, including a place of spot welding are most of all subject to corrosion.
Most quickly corrosion develops in the hidden cavities and the lower parts of a body at hit of moisture, dirt, salts, acids. In this regard in use the car for additional protection of internal surfaces and the hidden cavities of a body put special anticorrosive structure, and in connections of details — sealing mastics.
The anticorrosive structure which process internal cavities of a body and the bottom, should meet the following requirements:
– to contain corrosion inhibitors;
– evenly to be distributed on all processed surface and to form the protective film resistant to vibration and temperature drop;
– to have good adhesion with elements of a body or earlier put coverings;
– to be compatible to put earlier paint and varnish coverings and anticorrosive structures;
– to keep the physical and chemical properties long time under the influence of external factors;
– to contain materials which when processing the car answer standards of fire and ecological safety.
Movil or Movil-2 autopreservative use for processing of the hidden cavities. It is recommended to process cavities every 1-1,5 year. Autopreservative allows processing of the surfaces, earlier covered nigroly or other oils, and also rusty surfaces.
Protective lubricant NGM-ML apply to processing of the hidden cavities. This material processed the hidden cavities of new cars. Protective film covering NG-216B use for a covering of parts of the car under a body. Mastic antinoise bitumen BPM-1 apply to protection of the bottom of a body against corrosion and for noise reduction. Thickness of a covering of 1,0-1,5 mm.
Пластизоль D-11A use for protection of the bottom of a body against corrosion, abrasive wear and for a noise isolation. Thickness of a covering of 1,0-1,2 mm. Plastizolem D-11A the bottoms of new cars are processed.
Пластизоль D-4A it is intended for sealing of welded seams. Non-drying mastic 51 - G-7 is recommended for sealing of joints of a body.
In internal cavities anticorrosive substance напыляют in the way of air and vacuum dispersion.
At air dispersion the compressed air under the pressure of 0,5–0,8 MPas, the gun spray with a tank, hoses and lengthening nozzles for the gun is required. The best quality of a covering is reached at vacuum dispersion under the pressure of 4–12 MPas which allows to spray materials of considerable viscosity.
For mechanical protection of arches of wheels against small stones and sand use podkrylka from the plastic, in addition established on the car. The main shortcomings of podkrylok — drilling in a wing of additional openings for their fastening, deterioration of ventilation of wheel arches, a dirt and salt congestion in vystupaniye places a podkrylka over a wing otbortovka. To protection of a paint and varnish covering of a forward part of a cowl and the lower part of doors apply special anti-gravel transparent being self-glued films.