Author Topic: Polished electrodes...  (Read 5320 times)

0 Members and 1 Guest are viewing this topic.

Offline Login to see usernames

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3633
Re: Polished electrodes...
« Reply #24 on: March 27, 2016, 12:52:07 pm »
here the images

the tubes that have a white like look were polished like this before geting into the cell last year but ended up with lot of pitting and covered with this white like but actually is very tyni corrosion point in ss

part of the dirty come from the spring that is inside the electrical connector to the tubes and rods...
 
the spring  aparently not a good stainless steel... the manufactor said it was 310 ss but it rusts a lot ...

maybe some hardening of the stainless steel would be desired if we could some how achieve it




Offline Login to see usernames

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3633
Re: Polished electrodes...
« Reply #25 on: March 27, 2016, 16:08:28 pm »
i did a citric acid solution with 500g of water and 50g of cirtric acid anidrous..

at the start it made like 5 minibubbes on the polished surface..

i degreased with acetone...


Offline Login to see usernames

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3633
Re: Polished electrodes...
« Reply #26 on: March 27, 2016, 22:54:13 pm »
i decided to leave more time the electrode on the citric acid since it seem is not doing anything to it...

i will probably find some nitric and do the process with it after...

i will place the electrodes on hydrogen peroxide to try oxidize a litle deeper.. probably i will add some to the citric acid to see what happens...

i read that citric acid alone is not as good as nitric acid for this process since nitric is also an oxidizer
so you must provide some oxigen to create the passivation layer..

the electrodes didnt changed apearance there was a piece inside the rods with scaling and it didnt came out either...

the spring was also diped into the solution and left... after some time the red rust became dark and it bubbles a lot.. i took it out and used some car polishing paste and a piece of fabric and cleaned it it became very shiny.. than i degrease and dip again into the citric acid and it again bubble and become brown ... this grade of ss is not good sorry steve i guess we must change it for 304 maybe.

i will try to leave it on the citric acid for a while and see if maybe the iron comes out of it otherwise i´m thinking about plating something over it to stop the corrosion... maybe nickel or chrome nicklel... dont know ... maybe palladium...

however the faster way will be to find here someoneelse than can make them for me with 304..


the screws where the springs go in didnt rust at all.. .this may be very well passivated or electropolished or something...