The insidiousness of corrosion it is well known: it is enough to see a small scratch, for example, on the body of the car as rust begins to absorb the metal. And both suffer from corrosion of conventional water pipes, and other hidden in the ground steel construction!
To combat corrosion is difficult. Take, for example, protective paint and the polymer coating. To efficiently handle those most affected places sometimes you have to disassemble the machine itself.
Besides, any coating, alas, is not eternal. Their lifespan reduces not only aggressive influence of environment. Because of the vibration appear here and there cracks, crack protective coating itself. The automotive engineering and other agricultural machines of this destructive process is enhanced under abrasive the influence of soil, stone impact. So understand the desire of car owners and the owners of farmsteads to spend money once and for all to protect your technique from rust.
Many opt for the so-called cathodic protection. Among the leaders here - the builders and operators of pipelines. Before the styling of the finished section of the pipeline anti-corrosion treated compositions and wrapped with protective tape. At some distance from the road buried anode (electrode)- metal blank, which then is connects plus DC source, and to pipeline - minus. Due to the potential difference between the electrode and shielded metal through the electrolyte is formed from moisture, salt and other chemicals contained in the pound, passes current. The oxidation reaction, i.e. the release of electrons occurs at the anode, the resolving process of the cathode is stopped and its the safety is guaranteed.
During the cathodic polarization of the metal is necessary to report a negative potential, at which oxidation becomes thermodynamically unlikely. For iron and its alloys full corrosion protection is achieved at 0.1 to 0.2 V. Further the shear capacity has little effect on the degree of protection. The density of current to be in within 10 to 30 mA/m2.
Of course, cars and tractors, tillers and other agricultural equipment - not the main pipeline. Cathodic protection of these mobile tools has its especially though, because they already have and the current source, and the in-vehicle network wires, and corrosion-resistant coating, reinforced with a special compound. Plus as plenty of vibration and dynamic loads plus excessively aggressive road environment.
We offer homemade device allows you to maintain the value of the potential wet the surface of the body or housing of the machine at a level necessary stop stop and stop corrosion processes due to the destruction protective electrodes (anodes). Their quality can be used as collapsing materials (stainless steel, aluminum), requiring replacement through 4-5 years, and persistent (for example, carboxyl, magnetite, graphite) in the form rectangular or round plates with an area of 4 to 9 cm2.
Rectangular and circular electrodes, and a circuit diagram unit for anti-corrosion cathodic protection equipment.
Of course, in the simplest form of cathodic protection can consist only of a metal electrodes connected to the plus of the battery. But then it is difficult to control possible short circuit of the electrodes on the car body and the operation of the device in General. That's why you need a simple electronic component that consumes from the paltry battery current (about 2mA).
If one of the shield electrodes will suddenly start to close on the car body (body farm machinery), the indicator HL1 stops glowing. Immediately disconnect the power source and start Troubleshooting circuit.
Reacts semiconductor indicator HL1 and high humidity of the body cars-dimming glow, indicating enhanced cathodic work protection.
When using this protection from corrosion should be remembered that one electrode provides cathodic preservation of 0.2-0.4 m2 of metal surface. Such electrodes are installed only on the places protected paint coating. And fixed with epoxy glue or putty, and the outer side of the electrodes must remain free from any electric insulation.
The electronic unit is placed anywhere on the car (tillers, tractors and etc.) and connected to the electrical system so that it remains constantly included (except for emergencies when it is necessary urgently to disconnect).
Consuming current is not more than Electromechanical clock in the car, cathodic protection ensures long-term efficient operation even with highly a weak battery.
Literature
Author: P. Bialiatski, Berdsk, Novosibirsk region