Who has a car know that smal scratch may cause a rusting which will expand even under painted areas. And fight rusting id pretty hard tas. And so there are lots of methods that car keepers using. Ones are using anti-rust coating… but it has shortcomings – succes depends on how good it have been done. Area needs to be cleaned with care and sometimes requires to to pieces a car. So such operation requires decent amount of time and requires constant control. Besides this car is always in stressed environment: cold, salt, water, vibrations, stones and so on. There is always a chance of damaging surface coating. Because of this there came a device which requires only one installation which protects from rust.

Cathode rusting protection isn’t new thing. It has ben used for protecting various object on and under ground. Even ships are using cathode protection. The idea is to use special protector who melts in sour water instead of protected metal. Water piping companies who use metal pipes first of all paints pipes with protection coating then wraps them in special tape and then at some distance places another metal electrode(Anode) protector and connect to it (+) ant to the pipe(Cathode) (-). Because of voltage between electrodes electrons flow to cathode from environment. In the anode side opposite – electrons are freed and so oxidation reaction starts this way anode metal dissolves.

Cathode negative voltage has to be selected which is high enough to stop oxidation. For instance to stop rusting an Iron or its alloys there is only 0.1 – 0.2Volts needed. Higher voltages have no additional effect. Current density should be about 10 – 30mA/m².

During some time period because of oxygen concentration there accumulated additional negative voltage. This allows periodically disconnect protecting device for some time.

Cathode rusting protection device is very simple. You need two main blocks – electronic part and protective electrodes. Electronics block may have LED indicator which indicates that device is ON.

This device allows to maintain several decimal parts of volts on the car body what is enough to stop rust process and starts destructing protective electrodes(Anodes). Anodes can be same metals as car body(iron, aluminum) or other materials like magnetit, graffite. They have to be replaced every 4- 5 years. They usually are shaped as square or circular plates with area 4 – 9 cm². It is important to make sure that electrodes didn’t short-circuit. In case of this LED indicator will stop indicating. LED light intensity may change because of changes of inductance variations because of environment changes e.g. Salted road in winter.

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This entry was posted on Wednesday, May 16th, 2007 at 12:36 pm and is filed under Free Hobby Electronics Circuits. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.