OK Mainsail, now its time to spray some clear lacquer on that valve .... ;-)I don't advise using the product in this manner, not its intended use, but I did do it.
Future Rust Prevention For Ends of Saw-Cut 316 SS Tubing?
- Thread starter rardiH36
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Re: Future Rust Prevention For Ends of Saw-Cut 316 SS Tubing
I've gotta ask Maine. What is that dark sealer under the backing plate?
I've gotta ask Maine. What is that dark sealer under the backing plate?
Thickened VE resin with strand, milled fibers and cabosil. Used a blue die in the MEKP to judge mix.....
Didn't know that, Ospho was a suggestion tossed about on a metal working forum. Though, that spotless stuff looks to be helluva lot better
Re: Future Rust Prevention For Ends of Saw-Cut 316 SS Tubing
Somebody please explain briefly the science behind passification? I read about it , hear about it, but never really understand it.
Somebody please explain briefly the science behind passification? I read about it , hear about it, but never really understand it.
Re: Future Rust Prevention For Ends of Saw-Cut 316 SS Tubing
Several functions of passivation:
Metal are composed of 'microscopic grains' or teeny 'islands' of micro-alloys instead of a uniform homogeneous mixture of the metals which compose the material.
• Passivation extracts or removes the more reactive surface elements, chiefly ferric iron. Nitric, Citric and Phosphoric acids attack and extract chiefly the ferric iron molecules, thus removing them from the surface. Ferric rust is 'red' rust. Ferrous rust is 'black or blue' rust which in iron based metals is 'protective' but can reduce to 'red' rust.
• Planar passivation removes the hills and valleys from the surface roughness. Especially in 'stainless alloys' which are subject to 'crevice corrosion', the more 'planar' (flat) the surfaces become, the less prone to develop such 'crevice corrosion' in the 'valleys' between the peaks of the roughness. Planar passivation is accomplished by mechanical grinding/polishing/buffing and for critical service is usually followed by electropolishing (a reverse form of electro-plating and where the removal of irregularities/roughness is easier accomplished due to the relative higher 'reactivity' at the peaks and valleys of the surface roughness). Electropolishing 'rounds off' the sharpness of the microscopic peaks and valleys, thus increases the 'flatness' on a microscopic basis.
The problem with chemical passivation (only) is that one can 'go too far' and extract too much of the surface iron thus creating deeper valleys between the 'micro-grains' thus making common (300 series) stainless more prone to crevice corrosion.
FWIW - passivation of 'steels' and cast iron.
For simple steels and cast, etc. irons (not stainless steels) passivation can be accomplished by removing surface roughness (polishing, etc.) and simply 'boiling/soaking' in hot water for extended periods ... changes any 'red' rust to protective 'black' rust -- called 'blueing'. Cast iron is easily 'blued' and is the reason that cast iron engine components last so long because of the formation of surface ferrous (black) rust in the internal water passages ... IF the engine is often and repeatedly run to HOT. (Also is the reason that navy ships keep their engines running ... and HOT).
Here's a very highly 'technical' description of grain boundary degradation in 300 series stainless: http://144.206.159.178/ft/940/92165/1600215.pdf
Several functions of passivation:
Metal are composed of 'microscopic grains' or teeny 'islands' of micro-alloys instead of a uniform homogeneous mixture of the metals which compose the material.
• Passivation extracts or removes the more reactive surface elements, chiefly ferric iron. Nitric, Citric and Phosphoric acids attack and extract chiefly the ferric iron molecules, thus removing them from the surface. Ferric rust is 'red' rust. Ferrous rust is 'black or blue' rust which in iron based metals is 'protective' but can reduce to 'red' rust.
• Planar passivation removes the hills and valleys from the surface roughness. Especially in 'stainless alloys' which are subject to 'crevice corrosion', the more 'planar' (flat) the surfaces become, the less prone to develop such 'crevice corrosion' in the 'valleys' between the peaks of the roughness. Planar passivation is accomplished by mechanical grinding/polishing/buffing and for critical service is usually followed by electropolishing (a reverse form of electro-plating and where the removal of irregularities/roughness is easier accomplished due to the relative higher 'reactivity' at the peaks and valleys of the surface roughness). Electropolishing 'rounds off' the sharpness of the microscopic peaks and valleys, thus increases the 'flatness' on a microscopic basis.
The problem with chemical passivation (only) is that one can 'go too far' and extract too much of the surface iron thus creating deeper valleys between the 'micro-grains' thus making common (300 series) stainless more prone to crevice corrosion.
FWIW - passivation of 'steels' and cast iron.
For simple steels and cast, etc. irons (not stainless steels) passivation can be accomplished by removing surface roughness (polishing, etc.) and simply 'boiling/soaking' in hot water for extended periods ... changes any 'red' rust to protective 'black' rust -- called 'blueing'. Cast iron is easily 'blued' and is the reason that cast iron engine components last so long because of the formation of surface ferrous (black) rust in the internal water passages ... IF the engine is often and repeatedly run to HOT. (Also is the reason that navy ships keep their engines running ... and HOT).
Here's a very highly 'technical' description of grain boundary degradation in 300 series stainless: http://144.206.159.178/ft/940/92165/1600215.pdf
Re: Future Rust Prevention For Ends of Saw-Cut 316 SS Tubing
I googled something yesterday and found mixing mollassas (one part) with water (nine parts) makes phosphoric acid (think Coka Cola) and can be used for what you want it to do. Removes rust and passifies, and cheap!
I googled something yesterday and found mixing mollassas (one part) with water (nine parts) makes phosphoric acid (think Coka Cola) and can be used for what you want it to do. Removes rust and passifies, and cheap!
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