Research On Evaluating The Performance Of Military Vehicle Protective Coating And The Corrosion Of Cooling System's Metal

Military vehicles(MV) were long-term used in the bad weather,such as sandstorm,rain-snow,wet and salting fog. These factors can cause serious corrosion. The behavior of corrosion concerns many factors. In addition to natural environment, vehicle's usage and designing aspects also were involved. In this thesis,the vehicle corrosion problem were studied from two aspects. One is the evaluation of the performance of protective coating,the other is based on studying the corrosion of cooling system's metal in different working temperature and liquid. The according measures were usually adopted after the question occurred,because of the two aspects are easy to be ignored,and the result is the increase of the cost of the use and maintain of military vehicle. This paper focus on the test and evaluation of the performance of protective coating and the corrosion of cooling system's metal. The main research contents are as follows:The influence factors of the failure process of military vehicles coating were analyzed,and researching on the performance of green and black protective coating of the military vehicles.The results manifest that the coating's performance is quite different from each other,even if it seems like perfect from the surface. The simulation of various degrees of the damages is presented,the coatings sample of various degrees of the damages were made and electrochemistry test was carried out,the data is processed by the software of Zsimpwin,and many electrochemistry parameter such as Rf,Zfmin and ZAVG are extracted,the change curve of these electrochemistry parameters with the coefficient K of the coating's damage degree is built and analyzed,and provide a theory clue for field testing and evaluation.The field test of military vehicles coating is presented,the EIS of coatings of various damages were analyzed. The model value of the low frequency was extracted,and the relationship curve of average value Z1 and Z2 of the model value of real vehicle test with bodywork coatings and the single parts is built and considered as the adjustment curve for real vehicle test in the theater. Estimate index is brought forward,and the field evaluation of the performance of coating using EIS are carried out,and try to evaluate various coatings. The EIS analyze of the coatings with different damages manifest that coating's performance is different from each other,even though the surface seems alike. The result show that efficient test and evaluation of military vehicle's coatings and maintain accordingly is very important to improve the efficiency of vehicles.Simulating cooling system's environment,the test selects customary metals cooling system usually adopted and three liquids to make the electrochemistry test according different temperature,and analyzes the corrosion of engine cooling system's metal. The result shows that the corrosion rate of cast iron increased with the temperature increasing in the three liquid,and the rate obtains a maximum level at 50℃,then when temperature increased,the corrosion rate slightly decreased; the corrosion rate of aluminum increased with the temperature increasing in the three liquid; the corrosion rate of brass in the coolant decreased with the temperature increasing, and has a minimum at 65℃,then increased with the temperature increasing,but in the other liquid the corrosion rate of brass reached a maximum at 50℃,then the corrosion rate kept stable. The result manifests that if the replacement of cooling fluid not in time for long time,it will badly corrode the cooling system of military vehicles.According to different cooling fluid and temperature with the various area ratio composed by Cu/Fe and Cu/Al,the galvanic corrosion has been studied and the galvanic current is tested,and the rule of galvanic corrosion is analyzed. The results show that the rules vary with the area ratio of galvanic corrosion's different poles. When the area ratio below or above 1,the rule will change accordingly. If the ratio is below 1,the relationship between galvanic density and area ratio is half logarithm linearity; if the ratio above 1,the relationship is very complex.Couple electric potential usually close to corrosion potential of anode metal as the galvanic corrosion of cooling system metal happen. Due to the electric current increase,with the raise of temperature in the temperature range,so the cooling system should not work for a long time under the condition of higher temperature.