GALVANIC CORROSION: CARBON FIBER + ALUMINUM | What is it? How we prevent it on the DarkAero 1!

[@DarkAeroInc]

For more composites related knowledge check out: www.darkaero.com/knowledge/composites/ Want even more? We also offer consulting: www.darkaero.com/consulting

[@ready-to-race]

Thank you for the video! Do you have an example on any parts with galvanic corrosion? I'm looking for some photos or video as some evidence that corrosion is an issue in discussion I had.

[@edthompson9569]

You are a gifted teacher! One small correction. Physical contact is not required for galvanic corrosion. The electrolyte is all that is needed to put two dissimilar metals in electrical contact. That's why the sacrificial zincs on a steel boat protect the entire hull and attachments.

[@lovrepeovic]

Metallic contact is neccessary.

[@jonasurfer4785]

@@lovrepeovic simply wrong

[@lovrepeovic]

Your knowledge of the problematics of galvanic corrosion on boats is obviously not sufficient. I do this for a living.

[@laurens4359]

@@lovrepeovic Metal contact is not necessary - e.g. the non metallic charge carrier will allow for corrosion, e.g. en.wikipedia.org/wiki/Galvanic_cell

[@ivanalvarez5511]

@@lovrepeovic only electrical contact is necessary, not necessarily physical contact. Meaning an electrolyte is sufficient. Think of electroplating

[@SkypowerwithKarl]

I see galvanic corrosion in all kinds of places with things you wouldn’t expect. On marine fuel tanks where the filler hose connects is very common. The hose is Coast Guard approved, wire reinforced rubber. When people put double hose clamps on at the very end of the hose it leaves a space above for moisture to collect between the hose and aluminum tank inlet tube. Well this moisture is a combination of condensation and fuel which turns acidic. When you have this acidic (electrolyte) in proximity of aluminum and the carbon black in the hose you get corrosion...lots! The solution is to place one hose clamp on the hose so it’s around the top of tank’s inlet tube and the other at the hose end. No accessible space to collect moisture. Yes there will be some limited corrosion at the top edge but it’s a non issue. Another place is the sender gasket. It’s made of chopped cork and rubber. Cork to wick and hold moisture and the carbon black in the rubber....perfect right? I replace these with fiber reinforced silicone gaskets. Same for metal tank straps, the the elastomer between the tank and strap can’t be rubber and a firm polyurethane is best. Devil in the details to make it right.

[@andrewstambaugh8030]

Great video and very good discussion of the various ways to handle this. I liked that you gave a warning about which side is better to paint (to avoid a focused corrosion attack at a scratch). thing that could possibly misleading people (your written description states this correctly, but doesn't call attention to it). [I'm sure you understand this very well, but for the sake of anyone watching who isn't familiar.] In your talking discussion, you say if the 2 metals/materials are touching, but: the 2 metals don't have to directly touch, as long as they are electrically connected, e.g. any bolt, wire, metal frame, or stray piece laying across them can act as a wire and electrically connect them. Example: If you are trying to protect your Alu by it touching copper, then copper to nickle, nickle to... up the galvanic chart. If the electrolyte connects from alu to the high galvanic (SS, titanium, or carbon fiber), it will cause high corrosion/galvanic corrosion, similar to if they were directly touching. (think of galvanic corrosion as being a battery like effect). In the marine industry, I have see some examples where people left tools or spare parts laying across things, that completed the circuit and caused excessive corrosion. (or commonly a found mistake, just left a spare SS pump or hydraulic fitting sitting on ALU where moisture would splash or condense.) It's also worth mentioning to people that Alu is praised for how it naturally forms a patina/protective layer, not rusting and pitting like steel... unless you galvanically corrode it! Then it pits deeply and turns to crumbly powder!

[@travers114]

Thank you guys so much for making these videos. So interesting and informative. This video is probably the best intro to galvanic corrosion on youtube.

[@CanineDefenseTechnologies]

I've been designing a carbon fiber rocket and thought oh shoot I should've known this, until the end lol 😂

[@MichaelT_123]

For small aluminium elements consider to finish them with the electroless Ni-P amorphous layer. The parts will be not only corrosion resistant but also light and ... shiny! Good job!

[@felixlabelle9041]

Very interesting dive into galvanic corrosion and the issues in bonding CF with metals. That disposable rocket exemple was awesome. Thanks for making this information public and engaging :)

[@dnogin]

You really have a deep dive into the issue. Enjoyed watching it.

[@whatelseison8970]

Some other good options include anodizing aluminum parts, and for metal objects that will be buried or immersed in water, cathodic protection is great where a steady source of power is available. Where it isn't you can always put your aluminum parts in contact with an even more active metal like magnesium (a sacrificial anode). Nice video. I enjoyed it.

[@fallencorporal]

I was wondering why they didn't consider anodizing it. It may have not been an option because they're connecting aluminum directly to the resin, the layer of aluminum oxide might prevent it from sticking altogether.. I'm sure google would be able to give an answer on that.

[@PH-G]

Love the drill bit pointer!

[@DarkAeroInc]

😁 Good eye! The drill bit is more my style.

[@Danieltredway1431]

You guys are so generous with your information. God bless you guys. I am tired of companies being so greedy with information. We need companies like this who have integrity and generosity. I always believe sharing will win because people will learn to trust you guys more because people want to know what they are getting to make the best decision. I also believe God will bless you more in the end.

[@augurelite]

These videos are awesome! Love watching the DarkAero progress :)

[@DarkAeroInc]

Thank you for watching! Glad you are enjoying the videos!

[@fly4fun24]

You couldn't Find a better Wand , I loved it along with knowledge I just Learned... You guy are bulding a very fine piece of Engineering..

[@RBAERO]

Very nice video! Question how you prevent corrosion on bolts and nuts like does we see on linkage at 5:55

[@justinmoritz6543]

Awesome videos! I’ve been loving these technical videos you’ve been making. Helping me understand engineering a WHOLE lot better

[@DarkAeroInc]

Justin, that's great to hear!

[@kellypyatt3144]

Very cool. i was wondering when you were going to talk about this.

[@zolotiyeruki]

I have two questions: 1) In a previous video (July 29), you walked through your process for selecting aluminum honeycomb as the core rather than using off-the-shelf panels with aramid cores, and mentioned temperature performance as a factor. Is the temperature issue a result of the aramid core itself, or is it due to other factors in the construction of the off-the-shelf panels? 2) How did you give the fiberglass layer the same honeycomb pattern as the core? Or is it a continuous sheet that just looks like it has the honeycomb shape because of how it was pulled apart?

[@justinw1765]

Aluminum is far more thermally conductive than aramid material.

[@rigilchrist]

It is impressive that you have such deep materials knowledge and a willingness to share such detail. It also evokes confidence in your product. One question: what about the exposed cut edges of the aluminium honecomb, such as you showed in the aft fuselage. Wouldn't water on the cut edge bridge the skin and core? (I appreciate that you are changing the core material for production, but I was just curious). Thank you again for you wonderfully educational videos.

[@DarkAeroInc]

Currently, we seal up exposed honeycomb edges with assembly adhesive but we are also testing out some other low density fillers. Thank you for watching!

[@HappyQuailsLC]

This was very helpful because we see a form of this take place with ancient artifacts which have been in the ground for many years.

[@manjus7063]

Brilliant teacher! Love your videos.

[@danielmiller2886]

Thank you!! Great info for us who aren’t (officially) engineers but still need detailed data and instruction.

[@drewski23_7]

Love that he used a drill bit as a pointer!

[@PiefacePete46]

Excellent... thank you. At 6:30 is shown a structural box-joint between honeycomb panels at right-angle to each other. Is there a method of avoiding aluminum/Cf contact in this situation?

[@tomcoryell]

Thank you very much for this. It changes my material choices for a project I have in mind.

[@theperson7718]

So what's the actual part of carbon fiber that's conductive? Is it the carbon fibers themselves or the bonding agent AKA resin? If it's the fibers themselves then well I guess there's nothing to do but if it's the resin then couldn't some of the resin companies make a non conductive resin to solve all these problems? Great video by the way. 👍

[@christopheraugustine5816]

Regarding the part about sealing things away from moisture, all I could hear was my father's voice. "You can never seal water out, all you can do is trap it inside when it gets there." Great video! Also, where do you get the honeycomb materials?

[@robertcloudman3676]

What is the weight difference between your sandwich panel core choices? It was the hardware rot going thru sandwich panels that got on my nerves. I went to stainless almost as soon as components were built. Corrosion slowed significantly but never eliminated totally. Silicon helped but not 100%

[@sefutho]

Wow! This would certainly help me a lot, thanks.

[@rooster700rr]

5:14 when you realize your professor is using a really long drill bit is as a pointing stick. (trust me, that is the correct technical name for a pointing stick, I googled it because I thought it would for sure, have a fancier name:)

[@ddegn]

I'm a chemist myself. I thought your video was fantastic.

[@anidiotinaracingcar]

Have you done a video in which you compare the strength of your honeycomb with something else (say a foam core, for instance)?

[@jakubrogacz6829]

If I need to embedd tube into carbon fiber would adding sillicone ( or any other plastic ) tube around help ?

[@scettzvill]

a 3d printed nylon inlet is non conductive. but isn't nylon highly susceptible to building static charge? how would that effect the contacting aluminum surface?

[@ΠαύλοςΡακοβαλής]

You Guys are AWESOME. Keep up the good work. Thanks for the videos

[@sw6006]

With your suggested change in the core material are you going to have to go through all the structural and vibration testing again?

[@truth7416]

I totally understand because of the simply clear way of your teaching. You need to consider starting a composite school.

[@1312iYo]

Great video, very informative yet easy to follow along! Having the prototype to show the different solutions added a lot!

[@DarkAeroInc]

Thank you and thanks for watching!

[@PoulHansenDK]

Thank you. Very Thorough and effective explanations..

[@justinw1765]

I don't understand the use of nylon on that one part, when S-glass fiberglass is far, far stronger?

[@trumanhw]

Alternatively ... did you guys consider using sacrificial anode..? Or inconel (not much more than steel)..? It's supposedly pretty resistant to corrosion.

[@jaypie0864]

Learned this years ago but this was such a better explanation!

[@DarkAeroInc]

Thanks Jay!

[@dariodamico3033]

What about grounding carbon fiber panel to discharge static electricity? How does this play into this? If you isolate the CF you don't discharge anything with the risk of charging the part.

[@C-M-E]

Late to the party as usual, but this an interesting area of study that has been arguably been tackled across a lot of different industries. In racing applications, ironically one of the first uses of bi-material composites, they don't particularly address it well, as most platforms are seen as essentially a limited lifetime chassis. Once it begins to form, the clocks are ticking on replacement. Aerospace is a little different, where coatings and even sacrificial anodes are used, both with pros and cons. Maintenance is generally high in this space, so upkeep of sacrificial bits go with the territory. The sacrificial route is also used in heavy cargo ships and waterway bridges. One of the somewhat overlooked areas particularly of concentration with aerospace is material interaction with static air charges building on operating and structural surfaces. Isolation in the core structure helps, but also needs a secondary strategy as the charge can build in operation beyond design specification depending on operating environment (naturally, you don't have much choice here).

[@gurdogarsargul9621]

Hi when you talk about galvanic corrosion you should also consider your SS bolt touching aluminum same problem, I have seen this in your video. Your aluminum parts will be corroded where touching SS. I have seen this in many airplane. I am building aluminum boat so have some serious experience on this subject. Try to use Tef-gel between dissimilar metal. You must also be very careful when electrification and wiring of your plane, always use two-polar thermal switch and never use ground pole. Success in your project.

[@hugoramos9481]

Hi there, is there a posibility to pasivate the aluminion core through anodization? does the anodization change the aluminium mechanical properties? did you consider this option?

[@crawford323]

I served 15 years on 500 ft research vessel and one of the ways the marine industry fights galvanic corrosion other than sacrificial metals was to electrify the hull with a very weak charge to nullify the difference in charges. I thought this was clever.

[@jarosawkamirski4718]

What about rust converter painted on the aluminium before carbon fiber layer?

[@tommcgee5491]

Hi There , whats the maximum working temperature of the carbon fibre and epoxy resin? Is it possible to skin a thin sheet of aluminum or copper with carbon fibre ?

[@foxmoth5477]

so the aramid honeycomb is less advantageous in the core compared to the need for a fiberglass intermediate between the aluminum honeycomb and the carbon fiber - and is less advantageous to the direct adhesion between the aramid honeycomb and the carbon fibres??

[@rustusandroid]

The air inlet, I feel, would be a good place for fiberglass use. The plastic will deteriorate over short time with the heat changes becoming brittle. It will be a constant replacement part.

[@braydend9582]

Have you thought about coating the aluminum parts with Cerakote H-900 Electrical Barrier or a similar product when in direct contact with carbon parts? I know you could anodize the aluminum parts but they would lack corrosion/chemical resistance. There are also dielectric epoxy adhesives that could be used to glue carbon and aluminum but I doubt they would have the same mechanical properties. All this extra coatings and work might just be extra since they might outlast the life cycle of the parts they are being applied too.

[@TekAutomatica]

What's weight gain for aircraft stored outside like airfields in northern Europe? Grob had similar corrosion issues with control castings and CF.

[@kevinkelly2513]

Did you use passivated titanium for the firewall?

[@Colorado_Native]

Just came across this channel. The SR-71 had a lot of titanium. To prevent GC a lot of the tools the mantainers used were also made of titanium. The USAF paid how much for one screwdriver? I can buy one at Home Depot for $2!

[@luddebosse1439]

i've seen people use a copper mesh below tha carbon fiber layer and honeycomb structure. In what way would this help against galvanic corrosion (if thats the purpose of it)?

[@johnmorey5166]

To prevent the galvanic corrosion :- must I insert an insulating layer between the Al and CF blocks in your diagram OR can I insert a thin titanium sheet to separate the Al and CF blocks which will still let the current flow but create Al/Ti/CF interfaces and not corrode in place of the Al/CF interface ? Cheers John

[@madtownbadger7115]

Nice work, Ryley, very simple explanation. This conversation is typically much longer than 12-mins in most meetings. Whether we are building a profile for farm equipment or a satellite at Exel Composites, fiberglass tends to be a cheap insurance policy against galvanic corrosion, with proper Resin selection.

[@DarkAeroInc]

Thank you Jared! It was actually a real struggle to condense this topic down so I wouldn’t feel bad if it took longer to go over this in a meeting! 😁

[@jessechen998]

A question off to the tangent, if I I layer the copper sheet on top of the aluminium core, then lay other sheets of fibers on top of that, does the conduction of the core and copper sheet helps reduce EMC further than just the copper sheet alone?

[@aaronokimoore]

Learned a lot! Your overview of the principles and going into the methods and options was really insightful. Curious, how you are doing accelerated testing?

[@robbeelsas]

Probably in an extremely humid test chamber with lots of salty water vapor

[@ДмКр-з6с]

Hi DarkAero, This is very informative video. Thanks for that! One small question. It could be seen from video that fuselage honeycomb sandwich frames edges also bonded to carbon fibre skin. How do you fight GC here or how are you ensure you frame's aluminium alloy core does not have contact with fuselage skin?

[@felixsu375]

How strong is the carbon fiber composite plate with aramid fiber core compared to the aluminum core in your carbon fiber sandwich?

[@DeksZagreb]

Why did you not opt for cork as the sandwich material between two layers of CF? It might be even stiffer than aluminum, and completely remove any galvanic corrosion risk.

[@scottjennifer7778]

How did you get past the delamination tendencies between fiberglass and carbon fiber?

[@madtownbadger7115]

Resin selection is key. We build "hybrid" carbon fiber and glass fiber parts at Exel Composites frequently using Pultrusion manufacturing.

[@RCCAD2VR]

I was also wondering the same 🙂

[@scottjennifer7778]

Might you do a video on this process?

[@christopheraugustine5816]

So long as your parts are being laid up at the same time, the resin should bond chemically from one layer to the next. Cured resin on the other hand, will only allow for physical bonding, like grabbing the surface of a basketball. Chemical is significantly stronger.

[@DMAX_DIY]

Very nice guys.. I'm trying to get some A HC for my CF project (which is a motion simulator). Nice information DMAX

[@DarkAeroInc]

Thanks for watching! :)

[@jerrymcarthur2062]

did you guys test how anodizing aluminum effects it?

[@muddasarakram419]

So I'm wondering, 3D printing hex bit holders in Nylon/CF probably isn't a wise idea?

[@ja2706pw6u]

Very Nice Video !!! I learned a lot !!! Thank you so much !!!

[@danielleriley2796]

The aramid honeycomb would be excellent in areas that are permanently sealed and as such no access for inspection or easy inspection.

[@kcsnow9447]

I might have run into this issue in an old house, wherein I was attempting to have a plumber bring a natural gas furnace back online after five years or so of non-use. Black iron pipe used most everywhere, but galvanized metal elbows in the corners...and he started frowning when he looked at it closely. "These elbows were intended only for water mains, and whoever built this (back in the 1950's) should have known this...but just might not have known about it." This Old House, indeed.... In the end he went all the way back to the meter, and started over again, as those elbows were used in every bit of the gas main. So: Is natural gas considered an electrolyte bridge? Are galvanized pipe and black iron actually dissimilar metals? The metals were certainly in contact with one another, and the gas circuit was certainly grounded.... BTW, I'm not just some lost homeowner asking this, as dad had purchased and were starting to build an RV-6 until we realized the cockpit was too vertically confining for comfort, and the alterations were going to be very difficult and time-consuming. The RV-10 I tried on for size at our local airshow fit both of us (tall guys) a whole lot better...but then his health began to fail and that brought an end to the project. Even though he's gone, I'm still paying attention. "Go, men, Go," and thanks for the very informative videos!

[@MM-24]

so....why did you use aluminum honeycomb at all? What are the detractors of using Aramid? why wasn't that chosen in the first place? why don't you use carbon fiber honey comb?

[@jackswann6165]

Doesn't this galvanic action act like a battery? It leads to something like electroplating actions?

[@kadecooper246]

What is the pros and cons of nomex vs aluminum honeycomb structure?

[@DarkAeroInc]

Great question Kade! For the specific type of aluminum and aramid cores we are using, aluminum has a slightly higher strength to weight ratio and it is lower cost than aramid. However, aluminum core is a little harder to bond to the face sheets and it requires the added fiberglass layer for corrosion protection. The main reason we are changing to all aramid for production is we find it easier to work with in a mass production environment. Thank you for watching and for the question!

[@luigigalvani9601]

Bel video! Sapevi che ho inventato questo tipo di corrosione?

[@danielbasovitch5087]

Riley, what is your background? Aerospace engineer? Physics professor? When you talk and explain what your doing it is so comprehensive, it sound like a script, but I know it is not. It takes very qualified and intelligent people to design and build this BULLET!

[@solidkreate5007]

Yep we used that Nomex too. Been cut many times by sandwich panels.

[@Megadeth6633]

great video, what do you recommend for an easy etching to prep the aluminum?

[@KarlOnSea]

Excellent video, thank you. 👍

[@elliottscott6493]

Good stuff. Keep it going

[@MustadMarine]

Dissimilar metals making contact: directly in contact or via an electrolyte or both. Once should not exclude the other, IMO Good vid

[@didimedina4858]

I learn so much from this channel, tha k you so much for the quality videos y’all put out! How would you address galvanic corrosion in high heat environments? I’m building a grill and there’s points corten steel touches up with stainless steel and currently looking into solutions to prevent galvanic corrosion. Thanks I’m advance 🫶🏼

[@Thomas..Anderson]

Watching second video was enough to subscribe.

[@gdu370]

Does the galvanic corrosion ultimately strengthen of the carbon fiber with the increase of electrons

[@LaserRifle]

Dumb question, but can carbon fiber damage plastic if it's touching it for years? Is there a reaction between CF and polymer or other plastics?

[@kneedeepsnow16]

Could you use a carbon fiber honey comb structure?

[@promodracer2191]

Could you discuss carbon fiber printing, or a solution for the carbon fibers printing into a painted carbon finish hen exposed to sunlight and heat from sun.

[@williamreymond2669]

7:11] You haven't mentioned it, so I'll mention it, *cathode to anode surface area ratio (Ac/Aa).* Ac/Na ratio is the idea that when a large surface area of carbon composite material [anode] is coupled to small metallic parts such as: fasteners, bolts and nuts [cathode] the rate of galvanic corrosion can be extremely high. Galvanic corrosion on steroids in other words.

[@MJ-iy4fb]

How hard would it be to deposit titanium onto the aluminum parts creating a passive type aluminum? Ben over at Applied Science (KZbin channel) made a device that will deposit various metals onto just about anything. Would be cool if you could do this on a larger scale to accommodate the bigger parts.

[@heldermartinovsky]

Hi! Very interesting class!! I have a question: I'd like to use carbon fiber to fix or reinforce some aluminum bike frames. Can the epoxy resin used to glue and mold the carbon fiber be an insulator between the two materials and prevent corrosion? and What if I use a fiberglass cloth first? Thank you!!!!!

[@wellscampbell9858]

Epoxy alone won't ensure separation but even very thin glass will, easy to find online. I think you will find that carbon and aluminum are not very compatible if bonding is depended on for strength; Epoxy doesn't adhere well to Al (and surface prep becomes intensive) Also CF and Al thermal expansion coefficients are quite different, aluminum shrinks and expands a lot, carbon only a little. You can still use CF, but it helps to create a structure that holds itself in place whether or not the bond fails; i.e. make "boots" for joints that are thick enough to physically support the tubing absent lateral or shear strength along the bondline.

[@PaulTheWonder]

Great video!

[@filip1296]

Hi, great video. Why did you not make the air inlets out of glass fiber composite ? From my experience cheaper and stronger than SLS printing , and it seems you have composites production on a very high level :)

[@fallencorporal]

Although some carbon fiberglass is resistant to temperatures of roughly 300*, the resin may not have the same tolerances and would be subject to melting. Although I think his reasons for not using it there was to avoid corrosion.

[@justinw1765]

Galvanic corrosion is one thing, but how do you deal with the dissimilar expansion/contraction between carbon fiber and Al core?

[@hapybratt8640]

What are the other benefits for using the non-aluminum honey comb sandwich panels? Are they lighter?

[@DarkAeroInc]

Good question! The aramid core panel does indeed end up being lighter than the aluminum core panel. There are also manufacturing benefits that come with using the aramid core in the panel. As mentioned in the video, the aramid core does not require the insulating fiberglass layer in its panel's construction and is easier to handle without damaging.

[@LoudandProudBSE]

How do you feel about epoxy painting the carbon and anodizing aluminum? Im building carbon fiber valve covers with an aluminum flange and people are trying to convince me im going to burn my car down.

[@DarkAeroInc]

As long as you electrically isolate the two you should be fine. I’m guessing you are doing this on a car that you are working of frequently and you are looking under the hood often. Just keep an eye on it. Corrosion takes time. Monitor it and you can always swap it out. I was actually thinking of making some “forged carbon”valve covers on our airplane as a fun bonus project. I’ve seen guys do carbon oil pans with aluminum blocks.

[@LoudandProudBSE]

@@DarkAeroInc thats basically what I did. Its a chopped carbon cosmetic layer due to the complex shape.

[@LoudandProudBSE]

kzbin.info/www/bejne/gIuYeaGQapxlq80

[@lennysheldon7685]

just started watching your channel. In your design and engineering do you have to consider increased potential for lighting strikes because of carbon fiber?

[@mtcondie]

Waiting to see what changes are incorporated into the DarkAero 2.

[@lucasvinholigoncalves8829]

Great vídeo, congrets to the awesome teacher 👏👏👏

[@DarkAeroInc]

Thank you! I never really thought of myself as a teacher but I must say that trying to put together a short video on this topic gave me a much greater appreciation for the professionals who teach!

[@ExploreComposites]

Great video! Thats a nice way to handle the problem and I bet that thin ply of glass doesn’t add much weight overall. Will the switch to Nomex save you weight too or just improve the manufacturing process?

[@DarkAeroInc]

Thank you! The production change away from aluminum will provide a slight weight reduction and improvements in manufacturability.

[@wanderingfirbolg6738]

That's pretty common on older aluminium car bodies when placed on Molybdenum steel alloy spaceframe chassis.

[@nilosantos9715]

Tanks for sharing information