SS Passivation Process

[Zipstor]

I have scoured the forum about plate passivation and have not found much on this process.

It apparently make the plates to live longer in contact with aqueous solution.. Anyone familiar with this?

Here are some information about the process itself:

http://www.hho-research.com.au/Passivati...0steel.pdf

And here is how to actually do it.

http://www.mmsonline.com/articles/how-to...teel-parts

[benny]

(04-18-2010 03:30 AM)Zipstor Wrote:  I have scoured the forum about plate passivation and have not found much on this process.

It apparently make the plates to live longer in contact with aqueous solution.. Anyone familiar with this?

Here are some information about the process itself:

http://www.hho-research.com.au/Passivati...0steel.pdf

And here is how to actually do it.

http://www.mmsonline.com/articles/how-to...teel-parts

You'll probably find that NaOH and KOH are both adept at removing 'free iron' from stainless steel.
Could this passivation perhaps be the same/similar process as 'conditioning' your cell?
i.e. Several low production runs, and flushes?
Bear in mind that sometimes Alkalis can serve the same purpose as acids.

[thomasbala]

(04-18-2010 08:46 AM)benny Wrote:  

(04-18-2010 03:30 AM)Zipstor Wrote:  I have scoured the forum about plate passivation and have not found much on this process.

It apparently make the plates to live longer in contact with aqueous solution.. Anyone familiar with this?

Here are some information about the process itself:

http://www.hho-research.com.au/Passivati...0steel.pdf

And here is how to actually do it.

http://www.mmsonline.com/articles/how-to...teel-parts

You'll probably find that NaOH and KOH are both adept at removing 'free iron' from stainless steel.
Could this passivation perhaps be the same/similar process as 'conditioning' your cell?
i.e. Several low production runs, and flushes?
Bear in mind that sometimes Alkalis can serve the same purpose as acids.

I think this passivation process is for SS intended to be used in everyday applications such as a part of a tool or enclosure and thus the added protection of a coating of iron nitride (the nitric acid dip described) to prevent the formation of iron oxide. Any protective coating on SS used for electrolysis would appear to me to inhibit contact of the electrolyte with the SS electrodes and decrease HHO production. I would think the last thing you want to do is protect your plates at the expense of gas production. It would be like painting them. You actually want as much contact with the electrolyte as possible rather than trying to preserve them.

[staugur]

Passivation or pacification of stainless steel is simply a means of electropolishing the surface to give a much more polished surface.It removes surface blemishes,reduces surface area, and provides a smoother finish as you see on surgical instruments,tatoo equipment etc.It's exactly the opposite of what you want with electrolyser plates.
Mr Pochen tried this with the "cell" and it don't work.If you are not happy with sanded plates try getting them shot peened for maximum surface area.

[thomasbala]

(04-18-2010 02:13 PM)staugur Wrote:  Passivation or pacification of stainless steel is simply a means of electropolishing the surface to give a much more polished surface.It removes surface blemishes,reduces surface area, and provides a smoother finish as you see on surgical instruments,tatoo equipment etc.It's exactly the opposite of what you want with electrolyser plates.
Mr Pochen tried this with the "cell" and it don't work.If you are not happy with sanded plates try getting them shot peened for maximum surface area.

Wonder if running over the plates with an electric etching tool would have the same effect as shot peening?

[jbalat]

Guys if you think of a spark plug then the spark normally forms from the sharpest point. Some sparks plugs have 3 v grooves to initiate more sparks.

I think its the same for electrolysis where bubbles will form first on any imperfections in the surface.

I scratched my plates by hand using a hole saw and I noticed I am getting much more output than before.

I would like to believe that the best outcome could be achieved by machining a sharp grid pattern onto both sides of a plate ? This may not be ideal from a corrosion perspective since any burrs will also corrode away first... So definitely 316 or Nickel would be the way to go with the grid

[thomasbala]

(04-18-2010 03:45 PM)jbalat Wrote:  Guys if you think of a spark plug then the spark normally forms from the sharpest point. Some sparks plugs have 3 v grooves to initiate more sparks.

I think its the same for electrolysis where bubbles will form first on any imperfections in the surface.

I scratched my plates by hand using a hole saw and I noticed I am getting much more output than before.

I would like to believe that the best outcome could be achieved by machining a sharp grid pattern onto both sides of a plate ? This may not be ideal from a corrosion perspective since any burrs will also corrode away first... So definitely 316 or Nickel would be the way to go with the grid

Maybe a surface like 80 grit sandpaper? BTW, how's your leak problem coming?

[jbalat]

From Wikipedia.. Passivation...
"typical passivation process of cleaning stainless steel tanks involves cleaning with sodium hydroxide and citric acid followed by nitric acid (up to 20% at 120 °F) and a complete water rinse. This process will restore the film, remove metal particles, dirt, and welding-generated compounds (e.g. oxides)"

This is from oupower
http://oupower.com/phpBB2/viewtopic.php?t=2408

My understanding is that passivation does help to reduce corrosion sites by removing impurities so it sounds like a good thing. I agree with Benny that the other option is conditioning or even to a lesser extent simply filtering/replacing the first few hundred kilometers of electrolyte.

I think 80 grit is referred to in the d9 document. Only use it one way..Im just wondering if a machined finish would be more effective though ?

BTW Fixed the leak and mounted in the car. Just need to sort out the reservoir and bubbler bottles. I still have some kind of voltage leak which you can read about here
http://www.fuel-saver.org/Thread-Do-I-ha...s-dry-cell

[staugur]

Passivation refers to the chemical neutralization of the surface - increasing corrosion resistance.

Almost any stainless steel that you can buy has been rolled, machined and/or manipulated with carbon or tempered steel implements. This means that, in general, all of the stainless steel that you will ever buy off the shelf or re-manufacture will have an appreciable amount of steel worked into its surface. Without Passivation iron or iron oxide exists on the surface of stainless steel. When any machining or fabrication operations are performed, the condition is worsened. Aside from iron being deposited by tooling, it is also being entrapped underneath the “skin” created by the mechanical operation. In the metal industry this surface impregnated steel is referred to as "free iron".

This free iron corrodes easily. The corrosion process of iron is a very aggressive reaction. This reaction will in almost all cases start corrosion in the stainless steel. Once started, the corrosion of the stainless will continue to take place without the presence of free iron.

Electropolishing of stainless steel has two significant benefits besides the leveling of the work piece surface. First, the Electropolishing process will remove all free iron from the surface of the work piece. This has the obvious effect of eliminating the free iron corrosion up front. Secondly, Electropolishing removes material from the surface of the metal selectively. For example, Electropolishing does not readily remove the carbon from the metal because carbon is very electrochemically neutral. Further, the process does not readily remove chromium or nickel. The chromium, nickel and carbon, for all practical purposes, becomes uncovered and remains sitting on the surface of the metal as the Electropolishing process takes place.

As you Electropolish a part you start enriching the surface with chromium and nickel. At some point, a chemical reaction takes place during processing of the part. The chromium reacts and forms chromium oxide. Further, if the surface is very rich in chromium, the chromium oxide will form what you can think of as a layer over the metal surface. This is referred to as a chromium enriched surface oxidizing to form a chromium oxide Passivation layer. This mechanism is referred to in the industry as "Passivation."

The term "Passivation" is used widely in the stainless steel processing industry. Many people refer to this oxide surface as a chrome-nickel oxide.

As Electropolishing solution removes the iron ions from the surface of the part, it leaves much of the chromium, nickel and carbon behind on the surface of the metal.

In 1962, General Dynamics/Astronautics Division in San Diego recommended the use of Electropolishing to increase the corrosion resistance of stainless steel in propellant systems to NASA.Their conclusions were based on actual accelerated seacoast exposure tests.

Tests conducted to determine the Passivation effects of the Electropolishing solution on stainless steel showed that this treatment greatly increased the passivity over that of conventional methods of Passivation. Specimens of 300 series stainless steel, contaminated and then treated by various methods, were exposed for approximately 560 hours to a salt spray environment. All of the specimens passivated conventionally (nitric acid at varying temperatures and concentration) showed a considerable amount of rust after 8 hours and were removed from the test while the Electropolished specimens did not show any change until after 40 hours. At this point light stain was only observed in the center of specimens. After 146 hours, light rust, lighter than that formed on conventionally passivated samples, was observed on the Electropolished parts.

[thomasbala]

(04-19-2010 07:40 AM)staugur Wrote:  Passivation refers to the chemical neutralization of the surface - increasing corrosion resistance.

Almost any stainless steel that you can buy has been rolled, machined and/or manipulated with carbon or tempered steel implements. This means that, in general, all of the stainless steel that you will ever buy off the shelf or re-manufacture will have an appreciable amount of steel worked into its surface. Without Passivation iron or iron oxide exists on the surface of stainless steel. When any machining or fabrication operations are performed, the condition is worsened. Aside from iron being deposited by tooling, it is also being entrapped underneath the “skin” created by the mechanical operation. In the metal industry this surface impregnated steel is referred to as "free iron".

This free iron corrodes easily. The corrosion process of iron is a very aggressive reaction. This reaction will in almost all cases start corrosion in the stainless steel. Once started, the corrosion of the stainless will continue to take place without the presence of free iron.

Electropolishing of stainless steel has two significant benefits besides the leveling of the work piece surface. First, the Electropolishing process will remove all free iron from the surface of the work piece. This has the obvious effect of eliminating the free iron corrosion up front. Secondly, Electropolishing removes material from the surface of the metal selectively. For example, Electropolishing does not readily remove the carbon from the metal because carbon is very electrochemically neutral. Further, the process does not readily remove chromium or nickel. The chromium, nickel and carbon, for all practical purposes, becomes uncovered and remains sitting on the surface of the metal as the Electropolishing process takes place.

As you Electropolish a part you start enriching the surface with chromium and nickel. At some point, a chemical reaction takes place during processing of the part. The chromium reacts and forms chromium oxide. Further, if the surface is very rich in chromium, the chromium oxide will form what you can think of as a layer over the metal surface. This is referred to as a chromium enriched surface oxidizing to form a chromium oxide Passivation layer. This mechanism is referred to in the industry as "Passivation."

The term "Passivation" is used widely in the stainless steel processing industry. Many people refer to this oxide surface as a chrome-nickel oxide.

As Electropolishing solution removes the iron ions from the surface of the part, it leaves much of the chromium, nickel and carbon behind on the surface of the metal.

In 1962, General Dynamics/Astronautics Division in San Diego recommended the use of Electropolishing to increase the corrosion resistance of stainless steel in propellant systems to NASA.Their conclusions were based on actual accelerated seacoast exposure tests.

Tests conducted to determine the Passivation effects of the Electropolishing solution on stainless steel showed that this treatment greatly increased the passivity over that of conventional methods of Passivation. Specimens of 300 series stainless steel, contaminated and then treated by various methods, were exposed for approximately 560 hours to a salt spray environment. All of the specimens passivated conventionally (nitric acid at varying temperatures and concentration) showed a considerable amount of rust after 8 hours and were removed from the test while the Electropolished specimens did not show any change until after 40 hours. At this point light stain was only observed in the center of specimens. After 146 hours, light rust, lighter than that formed on conventionally passivated samples, was observed on the Electropolished parts.

In one of the threads "Proof That Resonance Exists", either the closed one or the current one, Bob Boyce says when he was with Bob Potchin's outfit they electropolished and it cut production tremendously. I can see the benefits of electropolishing to preserve SS, but the issue isn't preservation but production of HHO. Anyone have any experience with increased or decreased HHO production with electropolished plates other than BB or BP?