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Corrosion on Aluminium parts (Moses fuselage)

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Onda
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Local Beach: North Sea (NL)
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby Onda » Thu Jun 14, 2018 7:06 am

bigcane wrote:
Wed Jun 13, 2018 9:14 pm
been riding Moses for over a year now. The white spots on the fuse you see after riding are usually grease spots that are originating from the screw connections. ...
Believe me, I´m quite able to distinguish grease spots from aluminium corrosion!

Onda
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Local Beach: North Sea (NL)
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Watergate Bay, Daymer Bay (UK)
La Torche (FR)
Style: strictly unstrapped
Gear: Ozone / RRD / Slingshot
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby Onda » Thu Jun 14, 2018 7:11 am

galewarning wrote:
Wed Jun 13, 2018 11:12 pm
The raised white crust usually occurs above pitting and is a hydrated form of the alumina, itself quite insoluble in water and to an extent protective. But it wouldn't be there so soon if the anodization was done correctly. In the interim, consider getting in a habit of wiping all the aluminum with something like Boeshield T9.
Yes, I'm a better materials science tech weenie than a kiter.
-Barry
Hi Barry,
thanks, this sounds helpful. Never came across this T9 stuff. I can buy a tiny bottle on German amazon for USD40 :roll: But will probably try it. Any special version of the T9 you would recommend?

I hope that Moses sees their fault and replace my fuselage without starting a mess about it.

Regards, Chris

plummet
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby plummet » Thu Jun 14, 2018 9:15 am

Onda wrote:
Tue Jun 12, 2018 9:30 pm
Hi all,
after having ridden my Moses foil in North Sea water for less than 3 hours during its first use I´ve been irritated to see clear signs of corrosion on the fuselage.
The shiny black (anodized) surface was covered with numerous elevated white spots of Al2O3 (alumina). These corrosion spots were centered around the screw holes for the mast and two areas where the wings are mounted.
I´ve put Li-grease on all screws before first water contact and have never left any parts assembled in wet condition (how could I - before first use).

The lapidary response from Moses (having received detailed pictures of the fuselage via my dealer) is: Send it in for analysis (2-3 weeks) or simply keep it and wipe it clean.

I´m kind of an expert for metal surface coatings... This is a clear quality issue from defective anodization. And any expert would be able to see it from my pictures. No need for "analysis"... if you´d like to call yourself a customer centric company. Needless to mention that this cannot be "wiped clean"! I´d have to sand it away, further thinning that anodized surface and worsening the issue.

What do you think?

Will post the pictures here when I´ve managed to upload them.
Though I am not a corrosion engineer nor a metallurgist I have a fair amount of corrosion experience in the aircraft and oil and gas industries. From your explanation, it does sound like the beginning of crevice corrosion. Your diagnosis of a breakdown in the protective coating seems entirely feasible. In the crevice between fuse/wings/screws, seawater can be trapped and deprive the crevice of oxygen. This leaves localized chemistry becoming increasingly reactive. As the passive oxide layer breaks down and cannot regenerate (due to oxygen deprivation)the voltage potential difference between the Cathodic anodized surface and the anodic pit in the crevice increased until a galvanic cell is produced. As the localized chemistry becomes increasing reactive and the voltage potential difference increases from anode to cathode the pit in corrosion increases at an accelerated rate.


What is the corrosion controls for crevice corrosion? Apply a protective coating. Remove electrolye solution (in this instance sea water), Allow for train holes. frequent wash down and drying.


Essentially we can consider corrosion like a battery. You have an anode, cathode in contact with each other and an electrolyte solution. If we can remove/separate any one of these we slow/stop the corrosion process. It is also worth notice that corrosion potential increases with temperature. An item that will corrode in salt water at 50Deg C may not corrode at 15 Deg C.


In practical terms ideas would be. Seal the mast/fuse/screws with lubricant/sealant. Ensure the electrolyte is removed after every session. Dry and store in a cool place. If you do not wash the salt water out of the crevice then place the foil in a hot car for house. That could propogate the conditions for corrosion!.... Also as the crevise becomes increasing reactive the temperature which corrosion takes place significantly reduces!...


Righto, Enough corrosion bable. Post some pictures. Its all conjecture until we see something actual.


PS. In my experience kiting/board building companies do not have a high level of corrosion knowledge. I doubt very much at all that they would have a metalurgist or corrosion engineer on staff. Their knowledge is redementary at best. The likelyhood is very high that the person inspection your photos does not have the slightlest clue about an anodic index, voltage potential differences or any of the finer details of corrosion mechanisms.

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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby Foil » Thu Jun 14, 2018 10:12 am

Brand new large fuse for Onda,
3hours use yesterday after removing previous white spots with rubbing compound.

Image

Image

Image

Image

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omg
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby omg » Thu Jun 14, 2018 11:39 am

well that doesn't look good? Now I would appreciate someone connected to Moses to chime in, please.

galewarning
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby galewarning » Thu Jun 14, 2018 1:33 pm

Chris,
WD-40 is better than nothing, but about the only thing it's good for is water displacement, "WD". There's a tiny bit of moly disulfide in it, pool a bunch and you will see it as the dark cloudiness, but WD-40 is neither a very good lubricant nor a protectant.
Info link [below] for Boeshield, which was originally developed to address issues with aluminum airfoils. It's a blend of solvents and waxes. BTW, I have no affiliation with the company.
-B

https://boeshield.com/about/

Onda wrote:
Thu Jun 14, 2018 7:11 am
galewarning wrote:
Wed Jun 13, 2018 11:12 pm
The raised white crust ...consider getting in a habit of wiping all the aluminum with something like Boeshield T9.
Yes, I'm a better materials science tech weenie than a kiter.
-Barry
Hi Barry,
thanks, this sounds helpful. Never came across this T9 stuff. I can buy a tiny bottle on German amazon for USD40 :roll: But will probably try it. Any special version of the T9 you would recommend?
I hope that Moses sees their fault and replace my fuselage without starting a mess about it.
Regards, Chris

Foil
Frequent Poster
Posts: 361
Joined: Mon Oct 23, 2017 7:44 pm
Kiting since: 2001
Local Beach: Newbrighton near Liverpool
Favorite Beaches: Flag beach for the Foil, Rhosneigr for the Foil and twintip.
Style: improving foiler.
Gear: Moses T38 full carbon Ltd edition. number 3 and number 56.
101cmMoses Carbon mast
Moses- 633 wave wing and stab
Moses 2018 637 race wing and stab,
Moses wings 590 and 548
Ozone Reo 6/8/9/10/12/
Nobile 50/50 twin tip
North 2018 click bars
massive grin
Brand Affiliation: None

Re: Corrosion on Aluminium parts (Moses fuselage)

Postby Foil » Thu Jun 14, 2018 2:03 pm

There is no way a spray or temporary solution is acceptable as a fix.
A fix is a replacement fuse when they get the anodisation process sorted, until then they are fine to use,
I have a 3 month old Onda fuse and it's fine
The week old Onda fuse is the one in the pics and that is not fine
And remember that I also received a new standard fuse on the same day, used 3 times now and is still in pristine condition.

Email and photos have been sent.
I have faith in Moses to sort this, but I expect it will take a few weeks which is not a problem for me.

Onda
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Local Beach: North Sea (NL)
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La Torche (FR)
Style: strictly unstrapped
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby Onda » Thu Jun 14, 2018 3:59 pm

Excellent, plummet. I studied electro chemistry and know a bit about electrochemical cells :wink:
The corrosion will always happen as soon as you bring Aluminium and carbon into electrically conductive contact and add an electrolyte (sea water). No crevice is neededf or this. However, a crevice - which stays wet for prolonged time - increases the issue.
Carbon has a much more positive electrochemical potential than aluminium, which means the Al gets oxidized by the carbon when brought into contact with each other plus electrolyte. The only means to protect the Al is to apply a protective (passive) layer on top of the raw Al. This is why you anodize the Al (= forming a thick and hopefully dense / tight layer of Al2O3 on the surface). Al2O3 btw has very desireable mechanical properties (stable, hard, robust) you will never be able to reach with any kind of paint or varnish.
BUT: Producing a dense, thick layer of Al2O3 is kind of an art and needs very deep understanding of the anodization process. One of the very tricky details is to "reach" into holes and cavities with the anodization. Holes are intrinsically shielded from the electric field in the acid (electrolyte) into which the Al part is immersed during anodization. No electric field, no anodization. This problem is particularly valid for anodization due to the very high current densities needed here (much higher than for any other "galvanic" coatings). So you have to take measures to get the electric field into every cavity, which is usually done by positioning separate electrodes right within the cavities - without touching the metal surface. This causes a lot of effort and cost for the anodization (manual work, needs a lot of attention to avoid short-circuiting during anodization). Another issue occurs with / near sharp edges of the Al part.... OK, it gets boring now :roll:
And certainly, the surface of the Al part has to absolutely perfectly cleaned before the actual anodization process (several steps of immersion into various detergents, acids, caustics, rinsing....). Even the slightest traces of fat / grease, silicone etc ruin the coating process. One touch by human skin: Ruined.

I always dismantle the whole foil after every use asap and rinse every single part (even the screws) with fresh water and dry it with a cloth, right after use before everything goes into my car.
But as I said, the corrosion signs became visible after 2 hours of use (the first ever use of the brand new foil) right at the beach!
Will post some pictures later.

plummet
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby plummet » Thu Jun 14, 2018 6:52 pm

Onda wrote:
Thu Jun 14, 2018 3:59 pm
Excellent, plummet. I studied electro chemistry and know a bit about electrochemical cells :wink:
The corrosion will always happen as soon as you bring Aluminium and carbon into electrically conductive contact and add an electrolyte (sea water). No crevice is neededf or this. However, a crevice - which stays wet for prolonged time - increases the issue.
Carbon has a much more positive electrochemical potential than aluminium, which means the Al gets oxidized by the carbon when brought into contact with each other plus electrolyte. The only means to protect the Al is to apply a protective (passive) layer on top of the raw Al. This is why you anodize the Al (= forming a thick and hopefully dense / tight layer of Al2O3 on the surface). Al2O3 btw has very desireable mechanical properties (stable, hard, robust) you will never be able to reach with any kind of paint or varnish.
BUT: Producing a dense, thick layer of Al2O3 is kind of an art and needs very deep understanding of the anodization process. One of the very tricky details is to "reach" into holes and cavities with the anodization. Holes are intrinsically shielded from the electric field in the acid (electrolyte) into which the Al part is immersed during anodization. No electric field, no anodization. This problem is particularly valid for anodization due to the very high current densities needed here (much higher than for any other "galvanic" coatings). So you have to take measures to get the electric field into every cavity, which is usually done by positioning separate electrodes right within the cavities - without touching the metal surface. This causes a lot of effort and cost for the anodization (manual work, needs a lot of attention to avoid short-circuiting during anodization). Another issue occurs with / near sharp edges of the Al part.... OK, it gets boring now :roll:
And certainly, the surface of the Al part has to absolutely perfectly cleaned before the actual anodization process (several steps of immersion into various detergents, acids, caustics, rinsing....). Even the slightest traces of fat / grease, silicone etc ruin the coating process. One touch by human skin: Ruined.

I always dismantle the whole foil after every use asap and rinse every single part (even the screws) with fresh water and dry it with a cloth, right after use before everything goes into my car.
But as I said, the corrosion signs became visible after 2 hours of use (the first ever use of the brand new foil) right at the beach!
Will post some pictures later.
Yeah man I agree. Looking at the photo's you have a breakdown of the passive oxide layer outside of the crevice. That means pitting corrosion most likely due to a poor or improper anodizing process. I would expect to see this sort of corrosion on an anodized foil after 1 to 3 years depending on the environment. Getting this type of corrosion in a matter of hours from new is clearly a manufacturing fault or material defect! The only way to fix this now is a) warrantee claim, B) sand back and remove all corrosion and apply a protective coating. IE etch primed and painted with high grade aluminium paint. To be honest that will be a workaround as the painted surface will at some point become scratched and corrosion will commence again rapidly!

Very dissapointing!

plummet
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Re: Corrosion on Aluminium parts (Moses fuselage)

Postby plummet » Thu Jun 14, 2018 7:00 pm

Side note. To break the galvanic cell between alloy and carbon you can space the 2 materials apart with something inert like a thin plastic. It still wont fix a faulty product! and the pitting corrosion extends past the point of a dissimilar metal reaction and into the a break down of the passive oixide layer in its own right.....

Hehehe. Too much nerdy corrosion talk!. Most peoples eyes glaze over when I talk to that sort of detail.


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