laundryhamperman

iTrader: (3)

Sitting through class as an engineering student, my professor starts a new section on corrosion and goes on a tangent on ways to prevent it. If you attatched zinc to a piece of steel, and put the object in saltwater, the zinc will corrode away sparing the steel from rust, until the zinc is completely consumed.

The prof. said that the japanese started to zinc coat the unibodies of vehicles in the mid eighties to prevent rust.

My prof. also said that they attatch baskets which contain zinc to the side of steel ships to prevent the steel from corroding, and refill the baskets when the level of zinc is low.

I might try some variation of this on my winter car(possilby attatch some zinc somhow to the frame rails and inner fenders). If anybody has any more info or experience, please share for the common good of owners of rusting FB's...

Whanrow

Anodes only work for electrolytic (also called galvanic) corrosion. I have a cruising boat, so have some experience with anodes. When metal is placed in water (like the lower unit of a sterndrive), it creates a small electrical current, causing corrosion. In the case of most pleasureboats, the metal is an aluminum alloy which is quite soft, and very succeptible to this galvanic corrosion. This same thing can happen when dis-similar metals are attached together. If you've ever attached galvanized plumbing pipe to copper without the proper insulating piece, you get corrosion. Water is usually the conductor. As a result, I have my doubts that it would work on a car as they are only splashed in water.

The zinc in the body metal is to resist corrosion. Think of a low grade exterior bolt for around the house - zinc plated. Doesn't rust immediately, but eventually.

Lee Lyons

if your that worried about rust do it the simple and cheap way...either don't drive it in the winters or when it rain...or take it to a garage and have them undercoat the hell out of the bottom of your car...

laundryhamperman

iTrader: (3)

i'm trying to start this other idea for experimentation, or at least debate.

Rust of iron or steel in water is 2Fe + O2 + 2H2O -> 2Fe(OH)2
The oxygen is in the water because there is realistically going to be dissolved oxygen in all water in the elements a car would be exposed to(or boat).

If you had zinc and iron together, and splashed water, or salt water on them, the zinc being lower on a table of standard emf series than iron, will act as an anode, and the following reactions will take place
2Zn + O2 + 2H2O -> 2Zn(2+) + 4 OH(-) + 4e(-) The Zinc will form Zinc ions (2+ charge) and will dissolve into solution with the hydroxide ions in the water. The 4 Electrons procuded make a current to the cathode, resulting in the following reaction
2Fe(2+) + 4OH(-) + 4e(-) -> 2Fe + O2 + 2H2O This means that if there is any iron ions in the water solution around the iron cathode, the iron ions will join with the free electrons and plate iron onto the existing iron.

If you had some existing Fe(OH)2, and it got wet in the process, and dissolved into the water solution, it could react with the hydroxide ions in the water plus the free electrons provided from the zinc reaction, it could potentially plate iron back onto the cathode. Or at least, the zinc will react, dissolve away and create free electrons, and spare the iron from oxidations. Unfortunately, from what i've read, rust which is Fe(OH)3, is insoluble, which means it will not convert back to iron in these conditions.

What i'm going to try is to get some chunks of zinc, and connect them electrically to the frame of my POS daily driver 1985 toyota and note the corrosion of the frame and the corrosion of the attched zinc over the course of the winter.

aussiesmg

iTrader: (1)

I have an old 7 winter beater and would like to try this out also, do I need anything special or just attach the zinc to the metal.

Vin

It will work but only as long as the zinc has good contact and only for the local piece. The contact between body panels is not good enough for one piece to work for the whole car. The contact between car sections may be great for harness common but not for what you need.

If you want to reverse rust try: http://www.treasureexpeditions.com/R...ectrolysis.htm
Don't use lye, baking soda is safer for you.
Don't pour water into the lye/baking soda, pour the lye into the water.
Don't connect the electrodes backwards or it will rust your peice really fast.
Once you reverse the rust the surface is very suseptable to rust, so prep it very fast or let it rust lightly and use rust converter.

purple82

This is the same thing that I remember from my material science class ages ago.

laundryhamperman

iTrader: (3)

yes, i was thinking of connecting maybe 3-4 pieces to each of the 2 frame rails, and then maybe 1-2 inside each fender well, and then more wherever high rust areas are.

Pele

iTrader: (28)

Check the bottom of my FB, the Civic wagon, or my truck, all 1980's cars and it's evident that it sure as hell didn't work.

Rx7carl

Well salt on the road will do that Pele. Fact of life. It will stop it for a short time, but the salt is deadly to steel chassis.

hammmy

20 year MTBF represents an engineering failure?

-dave

Vin

Unfortunately you need less zinc per panel not more for it to work. That also means you need to replace it more often as it is consumed.

Let me emphasize that it does work, as long as there is go contact. But, contact degrades quickly and must be cleaned up often. If you are willing to maintain it you will stop the rust, but it is a lot of work.

Pele

iTrader: (28)

Yes. I want them to violate the laws of chemistry and stop oxygen from bonding to my steel!

aussiesmg

iTrader: (1)

Obvious locations are the front fenders, rear fenders, rear wheel wells, main floor. Now a couple of questions will screwing the zinc via steel screws directly to the metal be enough contact. Is any electrical current required. I'm not educated in this area and if my questions are stupid I appologise.

edmcguirk

The problem is that the static electric charge will tend to migrate to the outer surfaces of the car. For example there is never any static charge on the inside of a conducting sphere, it's physically impossible.

The charge will tend to migrate to any pointy surfaces and to the outside of any convex surfaces. The concave surfaces will rust unless they are coated with a local surface of zinc.


Same idea as the circuits that use the car's battery to charge the car's frame and body. It sort of works but not necessarily in the places where you need rust protection.

laundryhamperman

iTrader: (3)

No current is required aussiesmg. The reaction creates its own current, a potential difference(aka: voltage) forms between the zinc and the iron, and iron, having the higher potential will attract the electrons given off by the zinc ions.

"Unfortunately you need less zinc per panel not more for it to work." - Vin

Why is that Vin?

Also, could you use electrical solder or a solder that will bond to the steel and zinc to create a good electrical connection? Maybe have to keep track of what the composition of the solder is because it might take place in the electrochemistry our cars tend to generate.

bERNIECMYK

or try this:

http://www.carcoon.com/

aussiesmg

iTrader: (1)

I know your joking, but our reasoning isn't to bubble our cars but so that we can drive/enjoy our cars in wintersnow and salt yet still delay the inevidible.