You may be hearing electrolysis for the first time, or may have heard of it, but don't know what electrolysis is. Electrolysis is a chemical decomposition produced by passing an electric current through a liquid or solution containing ions. Meaning, using electricity and a liquid solution, rust will be removed from the part we are cleaning.
Pure water also known and distilled water has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. With out these impurities electricity cannot flow. Imagine you're floating in a pool of distilled water, lets say you are molecularly clean and will not contaminate the distilled water. If an electrical wire falls into the pool of distilled water, you will not be electrocuted. Now imagine you're in a swimming pool, that pool has chemicals to help keep it clean, it has dirt, leaves, some level of bacteria, dead animals, lots of impurities. If an electrical wire falls into the swimming pool, you will get electrocuted because the impurities will carry the current through your body to ground.
Baking Soda Wash
In the electrolysis tank we add baking soda wash, also known as sodium carbonate to the water. Sounds like it washes the part, and it does to an extent, but the main function of soda wash is it's chemical compound as sodium carbonate. When dissolved in water, it becomes sodium and carbonate ions. This solution is known as an electrolyte, promoting the flow of electrons and enhances the electrolysis process.
Flow of electrons
When you think of a battery powering a light we think the electricity flows from the (+) positive post to the light and back to the (-) negative post. This is known as the Conventional current Flow. While this is useful in things like Kirchhoff’s law for calculations, it's actually not scientifically correct. Electrons actually flow from the (-) negative post to the light and then to the (+) positive battery post. Filling what are known as empty holes due to a difference in potential. Knowing which way the electrons flow determines how we hook up the (+) and (+) wire leads from the power source. Since we want the rust to come off the part and go to the sacrificial anode, we will hook up the negative wire to the part to be cleaned, and positive wire to the sacrificial anode.
Once the electrolyte solution is prepared in a non-conductor container i.e. plastic. You will need a sacrificial anode. The purpose of this is just how it sounds, sacrificial. It will sacrifice itself to receive all of the rust ions from the rusted part. Any bare steel will work fine, but if you can obtain graphite at a good price this will be your best option.
What should you use for a power supply? To get the electrolysis process to flow, you need a voltage of 1.23V. Typically you'll want a power supply that will give out 6V to 12V DC with around 2A to 4A of current flow for best results. Old school battery chargers (not the new smart chargers) can work, or a DC bench power supply.
Electrolysis process with an NP205 case
Below you'll view the rusted NP205 go through the electrolysis process. You'll notice electrolysis does not remove paint as this case was painted orange at one point in it's life. Another benefit of electrolysis is, it not only reaches the outside, but it also gets inside the case, into crevasses small cleaning tools cannot get into. At the end you'll see the steel rebar coated with layers and layers of rust. This is the first and biggest step in cleaning and preparing the transfer case for powder coating. Next the case will go to the media blast cabinet. Where the blast media does remove paint, rubber, and non conductive materials that electrolysis does not remove.