how to make steel nuts/bolts rust

[RCinSTP]

I am trying to make steel bolts and nuts rust so that I can determine the amount of torque needed to unscrew the nut from the bolt.

I have searched the forum and found diverse and conflicting information about the various chemicals so I thought I was post this as a new topic.

 

I have tried various recipes and combinations of chemicals to make bolts rust and/or corrode, I am not talking about a pretty patina on the surface but so that nuts are hard to remove from the bolts.

 

What are your recommendations for chemicals, ratios, durations, etc., and why.

Why do you think of common household bleach and Hydrogen Peroxide and in what ratio/mix?

How would Vinegar affect things?

What about table Salt?

Muriatic Acid?

 

What about covering the bolts with the solution as opposed to spraying the bolts so that the surface is exposed to the air?

I have tried so many different combinations of chemicals and various durations.

Thanks for any advice you can give so I can figure this out without all the hit and miss trials.

 

 

 

 

[StringJunky]

I am trying to make steel bolts and nuts rust so that I can determine the amount of torque needed to unscrew the nut from the bolt.

I have searched the forum and found diverse and conflicting information about the various chemicals so I thought I was post this as a new topic.

 

I have tried various recipes and combinations of chemicals to make bolts rust and/or corrode, I am not talking about a pretty patina on the surface but so that nuts are hard to remove from the bolts.

 

What are your recommendations for chemicals, ratios, durations, etc., and why.

Why do you think of common household bleach and Hydrogen Peroxide and in what ratio/mix?

How would Vinegar affect things?

What about table Salt?

Muriatic Acid?

 

What about covering the bolts with the solution as opposed to spraying the bolts so that the surface is exposed to the air?

I have tried so many different combinations of chemicals and various durations.

Thanks for any advice you can give so I can figure this out without all the hit and miss trials.

 

How about getting an aquarium air pump with an airball attached and putting that in a suitable sized container containing vinegar (or salt and water). The object surfaces will then have an active and constant supply of all rusting factors: air, water and electrolyte which should accelerate the process

 

The airpumps and airstones can be quite cheap:

 

http://www.virtualvillage.co.uk/dual-speed-control-fresh-salt-water-aquarium-air-pump-001492-089.html?utm_source=googlebase&utm_medium=shcomp

Edited November 16, 2010 by StringJunky

[Newbies_Kid]

I think vinegar just too weak to make the nuts&bolts corrode. I ever use a mix of vinegar and sodium chloride to simulated corrosion by acid rain at marine atmosphere and my sample got no corrosion product because that vinegar just dissolve it and wash it away.. so no rust, only corroded surface.

[mississippichem]

You need a strong oxidant. The reduction of [ce]O_{2}[/ce] is also pH dependent and lower pH shifts the equilibrium toward products. Wikipedia says the presence of a calcium electrolyte also accelerates the process but I don't know how. I would say use nitric acid, but i feel like you might end up with iron nitrate, I honestly don't know. Just remember you need a strong oxidant and low pH helps.

 

This can also be done with an electrolytic cell but you probably don't want to go there because you'll need a lot of supplies if your doing this at home.

Edited November 18, 2010 by mississippichem

[RCinSTP]

I Googled "calcium electrolyte" but I couldn't find anything. What do you recommend for an oxidant that is stronger than Hydrogen Peroxide? I also Googled Electrolysis rust and found that this is used to --remove-- rust, this is one method to remove rust along with Muriatic Adic and Vinegar so maybe I am using the wrong things.

[mississippichem]

I Googled "calcium electrolyte" but I couldn't find anything. What do you recommend for an oxidant that is stronger than Hydrogen Peroxide? I also Googled Electrolysis rust and found that this is used to --remove-- rust, this is one method to remove rust along with Muriatic Adic and Vinegar so maybe I am using the wrong things.

 

Electrolysis can also be used to make rust. Or it could be done with a voltaic cell (no power source). All electro-chemistry is theoretically reversible and most reactions are practically reversible.

 

Wikipedia:

 

Iron (III) oxide is a product of the oxidation of iron. It can be prepared in the laboratory by electrolyzing a solution of sodium bicarbonate, an inert electrolyte, with an iron anode:

 

[ce]2 Fe + 3/2 O_{2} + H2O -> 2 FeO(OH)[/ce]

 

[ce]2 FeO(OH) -> Fe_{2}O_{3} + H2O[/ce]

 

At about 200 °C, the iron(III) hydroxide converts into [ce]Fe_{2}O_{3}[/ce]

 

Electrochemistry is tricky to pull off though, conditions are usually quite specific. I don't know how much EMF should be on the cell though, that's an important detail.

 

As far as oxidants go, permanganates should have the electro-potential to oxidize the iron, but I don't know what the products would be.

Edited November 18, 2010 by mississippichem

[Newbies_Kid]

I like to share this link here, this just an example but usually this Pourbaix diagram was commonly used to control corrosion. Except cathode, anode, electrolyte and oxygen, Electrode potential and pH also play a vital role to determine corrosion. Corrosion DoctorBut in my opinion, its should be enough to use sodium chloride to make your bolts rust. And perhaps you should lower the pH a little to accelerates the process. but, too low on pH might cause a development of protective patina thus prevent further rust. So should be careful.

[mississippichem]

I like to share this link here, this just an example but usually this Pourbaix diagram was commonly used to control corrosion. Except cathode, anode, electrolyte and oxygen, Electrode potential and pH also play a vital role to determine corrosion. Corrosion DoctorBut in my opinion, its should be enough to use sodium chloride to make your bolts rust. And perhaps you should lower the pH a little to accelerates the process. but, too low on pH might cause a development of protective patina thus prevent further rust. So should be careful.

 

This would make an interesting cyclic voltammetry experiment. Observing to see if the Fe(II)/Fe(II) and Fe(0)/Fe(II) couples were reversible at varying pH values. Then see if the results line up with the pH dependent equilibrium derived from the balanced equation. It's interesting because [ce]Fe_{2}O_{3}[/ce] lattices are non-stoichiometric.

Edited November 20, 2010 by mississippichem