11.24.4. Anticorrosive protection of a body
At daily operation of the car the paint and varnish and anticorrosive covering of a body is influenced by an excited environment: противогололедные reagents (during the winter period of time), sand, small stones, vibration and temperature drops which cause occurrence of microcracks in a body sheeting through which water and oxygen get to a metal surface. As a result of influence on an excited environment body process of oxidation of metal (corrosion) which leads to loss to them прочностных properties begins, and presence in water of a considerable quantity of salts and acids only accelerates oxidation process.
Hollow profiles of a body, the bottom, the bottom parts of doors and racks, and also connections of details of a body, including a spot welding place are most of all subject to corrosion.
Most quickly corrosion develops in the latent cavities and the bottom parts of a body at hit of a moisture, a dirt, salts, acids. In this connection while in service the car for additional protection of internal surfaces and the latent 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 following requirements:
– To contain ингибиторы corrosion;
– In regular intervals to be distributed on all processed surface and to create the protective film proof 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 at car processing answer norms of fire and ecological safety.
Autopreservative "Movil" or "Movil-2" is used for processing of the latent cavities. It is recommended to process cavities every 1-1,5 year. Autopreservative supposes processing of surfaces, before covered нигролом or other oils, and also rusty surfaces.
Protective lubricant of NGM-ML is applied to processing of the latent cavities. This material processes the latent cavities of new cars.
Protective film covering НГ-216Б is used for a covering of parts of the car under a body.
Mastic antinoise bitumen БПМ-1 is applied to protection of the bottom of a body against corrosion and for noise reduction. A thickness of a covering of 1,0-1,5 mm.
Пластизоль Д-11А it is recommended for protection of the bottom of a body against corrosion, abrasive deterioration and for a noise isolation. A thickness of a covering of 1,0-1,2 mm.
Пластизоль Д-4А it is intended for hermetic sealing of welded seams.
Non-drying mastic 51-G-7 is used for hermetic sealing of joints of a body.
In internal cavities anticorrosive substance напыляют in the way of air and vacuum dispersion.
At air dispersion compressed air under the pressure of 0,5–0,8 МПа, a pistol-spray with a tank, hoses and lengthening nozzles for a pistol is required. Better quality of a covering is reached at vacuum dispersion under the pressure of 4–12 МПа which allows to spray materials of considerable viscosity.
For mechanical protection of arches of wheels against small stones and sand, besides the regular protection of arches established on manufacturer, use подкрылки from the plastic, in addition established on the car. The basic lacks additional Lockers — drilling in a wing of additional apertures for their fastening, deterioration of ventilation of wheel arches, a congestion of a dirt and salt in places выступания подкрылка over отбортовкой a wing. To protection of a paint and varnish covering of a forward part of a cowl and the bottom part of doors apply special антигравийные transparent self-glued films.