[maxvortex]

Hi.
I want to apply iron oxide on iron plate and copper oxide on copper plate.
I have done this in few basic steps:

- added ammonia chloride powder to iron oxide and mixed with water.
- applied this "solution" to iron plate
- dry it altogether in oven at 120 degrees Celsius for 1 hour.
-----------------------------------------
Made the same with copper oxide.
Now i want to fasten even more this oxide on plates.

One of the ideas was to put this already made ( copper or iron plate ) to ammonia solution and leave it for cca half hour.

The reason why i want to do this is because when i add those plates into 30% KOH solution ( edison battery ), some of the oxide will fall down from the plates.
Not much but it will "contaminate" the KOH solution.

What do you think about that ?
Could this be a way to make this work.

Max

 

[manofohm]

Do you know the level of oxidation for your iron plate? and your copper plate?

In either case though you could heat the plates with a torch till red and apply oxygen gas as it cools to fully oxidize or limit oxygen to minimally oxidize.

[maxvortex]

Applying oxygen gas is very good idea but i can not test it right now.

My goal is to make those plate oxidation as much as possible, because the higher the oxidation, the higher is the performance of the cell.

What do you think about the process that i described in my first post.
Can ammonia be used for creating this "oxide solution" and why ammonia ?

I found this construction process in one old how to manual but i dont think that this is the best way...
 

[curiouscat]

What's your intended application?

[manofohm]

It may work Ok I have had this happen unintentionally with dry ammonia gas to various iron pieces of iron lab equipment it leaves a coating of the stuff on practically any metal around it actually. i dont know that the same goes for aqueos ammonia on iron though. On copper I was trying to create a patina design by use of aqueos ammonia and can tell you that it didnt work very well most of it stayed as metalic copper. Copper though is much easier to make the surface oxidize then I think you think. Just heat it up on any fire until its good and red and let it sit in the air it will produce a surface layer.

if you need a thicker layer I have a method for copper as well: take two small sheets and place them in a light electrolyte solution about 1 inch apart from eachother and attach electrodes and crank up the variac  this will actually deposit a layer of copper oxide onto your electrode. you need a good amount of juice to get it to work though.

With out oxygen though the iron is a little more time consuming but pretty safe and easy by comparison. just dip a sheet of iron into water with a good  amount of electrolyte in it and repeat every few hours or days or whatever untill you have a good layer of oxide on it. yould probably want to wash it though otherwise you will have caked electrolyte on the sheet.

[maxvortex]

Application: edison battery cell

I dont know how to describe it but the best layer should be in form of some kind of paste because then the plates are completely safe when i apply KOH solution.

If the solution is too hard then the oxide ( creates by heating + air ) will fall dawn..
The ammonia creates harder solution but just on the iron plate.

[ajkoer]

Insert your Cu and Fe plates (separately) into a solution of Bleach (NaOCl)for a few moments depending on the desired level of oxidation. Rinse. Sample reaction:

 Cu + NaOCl --> CuO + NaCl

In my opinion, simple, effective, cheap, quick and you are controlling the level of oxidation.

Good luck.
 

[Vargouille]

You might have some success in preparing a solution of copper nitrate, spreading a thin layer over the metal, and heating it to decomposition. You'll have to do it multiple times for a good coat, but it could be better than the other option.

See http://www.youtube.com/watch?v=nvMVlhBmv7M&feature=plcp for an analogous process using manganese.

[maxvortex]

I created the layer on the plates on few ways but there is one problem with this "metalisation" process on iron plate. In edison papers, it described that one cell should be charged with less then 100mA. Of course i did not do that :-), so i charge it with one ampere. The iron layer was destroyed but not complete. If i disconnect from the dc source the discharge time of the cell is much faster then before. It will drop from cca 140mA to 25mA in few seconds.

If i charge it with less then 100mA then the discharge process is much more slower.

My question:
- Why do i need to charge it with so small current and what is happening in this process ( on the iron oxide plate) ?
- i know that this cell can be charged to one amp but it has to be in this order - 50mA, 100mA, 200mA, 500mA, one amp.

Why could i not charge it with 200mA on the first charge ?

Max