Bonding Aluminum with Epoxy

[jonny250]

I am also interested in bonding Aluminium. I am looking at bonding 5083 to 5083 or 5083 to 6082. My interest is in replacing welded butt or fillet connections and to fabricate a small boat in a 'clean' environment - no welding, no heat distortion. Just a fun project.
I have spoken with a tech guy at Huntsman/Araldite, and the recommendation is 2015 or 2014-1. the latter being more resistant to water ingress, but not as tough.
In general terms, the Huntsman comment is that the bond is likely to last for 'years' not 'months', but I couldn't get any better idea than that - it depends on the loads, environment, etc.
Grob, your comments are interesting, do you think that the inconsistency is to do with inconsistent surface prep (no disrespect intended)? or do you think it is to do with moisture ingress/use of the part?
The DnV certificate of the Araldite 2015 is for a specific use of internal deck plates to frames, and as such is not really a 'harsh' marine enviromnet, nor critical to the vessel safety. The West systems certificate specifies the ambient environment and does not reflect the more severe marine environment that is likely to be found in marine use.
I would love to hear of any other practical cases for these adhesives, but I suspect that the reason they are not being used commercially in the marine market is because they are not (yet) up to it and remain unproven (please someone tell me this is wrong and why :-) )
I am aware of silvestris which is an alu boat which was glued together, but it is hardly a marine use - kept in a showroom perhaps...

[yipster]

havent got the book in from the librairy yet, no marine application as i know of but "Fibre Metal Laminates" sounds interesting

Book Description
Fibre metal laminates were developed at Delft University of Technology in The Netherlands, from the beginning of the 1980s. This is a new family of hybrid materials consisting of thin metal layers bonded together by fibres embedded in an adhesive. As a result of this build-up, fibre metal laminates possess a mixture of the characteristics of both metals and composite materials. Initial development led to the `Arall' variant using aramid fibres, which was first applied on the C-17 military transport aircraft around 1990. Large-scale application became possible with a variant using glass fibres, dubbed `Glare', which was selected for the Airbus A380 super jumbo in 2001. This is the first book to discuss these new materials and it deals mostly with Glare. It covers most of the relevant aspects of the materials, from static mechanical properties, fatigue and impact to design, production and maintenance of aircraft structures. This book contains the basic information on these new materials necessary for engineers and aircraft operators alike.

[Guest625101138]

I have had a joint in a light weight alumium hull (0.6mm) that has regular use in fresh water for over a year.

The water tight joint comprised the sheet overlapping a 40mm wide, 3mm thick aluminium backing strip and the joint design allowed me to create hoop stress between the backing strip and sheet.

Surface prep was careful mecahanical clean with fine sanding and acetone wash. Then spray on Loctite 7075 activator on both surfaces followed by a thin bead of Loctite 324 adhesive on one surface. Its sets in a matter of seconds so the pre-stressing of the joint had to be done quickly. I would have preferred more time. You need tight dimensional tolerance on the joint because the adhesive spreads rather than clogs.

I also appiled a strip of 20mm wide by 1.6mm thick aluminium using the same method as a keel rubbing strip along the length of the keel. It was only tapped down while the glue set and it shows no sign of bond failure.

I would be reluctant to take a glued boat on an extended voyage but for something to muck about in it is a good way to get a hydrodynamic clean finish.

In my opinion the quickest method of making a small one-off boat is aluminium sheet screwed and glued using a mildly expanding polyurethane glue. The glue is more a sealant but also provides a little added strength. I use self-tapping screws but always drill first or just stainless screws and nuts. I now cut with a disc or jigsaw rather than with shears as the shears stretch the edges. A nibbling tool might work better for cutting a clean edge.

Rick W.

[mydauphin]

Originally Posted by Rick Willoughby

I would be reluctant to take a glued boat on an extended voyage but for something to muck about in it is a good way to get a hydrodynamic clean finish.

In my opinion the quickest method of making a small one-off boat is aluminium sheet screwed and glued using a mildly expanding polyurethane glue. The glue is more a sealant but also provides a little added strength. I use self-tapping screws but always drill first or just stainless screws and nuts. I now cut with a disc or jigsaw rather than with shears as the shears stretch the edges. A nibbling tool might work better for cutting a clean edge.

Aluminum is best bolted or welded together. Epoxy can be used as sealant but extreme care in mechanically cleaning surfaces must be done to allow epxoy to grab on to aluminum. Al is flexible, make sure epoxy type your using is made for underwater use and same flexibilty. Underwater I used welded joints with epoxy with fiber to protect Aluminum. For above waterline like boat house, AL bolted together and using epoxy as glue.

[mydauphin]

Originally Posted by Guest

Chris Krumm ---

I think Andy Marshall is correct. Due to the aluminum oxidizing the bond strength drops to 0 over time.

I have heard that there is an alodine process that works. I have been unable to find the cleaner (perhaps due to lnot looking hard enough).

I am testing 3m 5200.

5200 and even epoxy will eventually release if not mechanically bonded and allowed to vibrate loose. Moisture can be allowed to get in between. That is almost impossible to use.

[lazeyjack]

Originally Posted by mydauphin;

5200 and even epoxy will eventually release if not mechanically bonded and allowed to vibrate loose. Moisture can be allowed to get in between. That is almost impossible to use.

google fast foaming acid cleaner(hydrochloric)
Epoxy in my exp has not the ductility needed, it will crack away from the alloys when the alloy heats(as in tropics) and when the boat falls off waves(as at sea)
If you want to adhesive use Sika 11fc or 3m make some products\
Alodyne is a fabulous product and has been used in the aero ind and marine Ind for 50 and more years Dulux have it I think was their product

[grob]

"Grob, your comments are interesting, do you think that the inconsistency is to do with inconsistent surface prep (no disrespect intended)?"

None taken, I am sure the inconsistency is the surface prep, but I was very careful and really could not have done any better without nasty chemicals which is a route I am not prepared to go.


Gareth

[theoldwizard]

A bit off the topic, but adhesives are used to "strengthen" steel to steel joint in automotive unibody applications.

The Ford Mustang (specifically the convertible model) uses a combination of spot welds and adhesives to joint structural floor panels together. The adhesive is call "Motorcraft Metal Bonding Adhesive TA-1".

[jorghenderson]

Try submerging said mustang in salt water.

[theoldwizard]

Originally Posted by jorghenderson

Try submerging said mustang in salt water.

While not "submerged", we use a lot a salt on our roads in winter to melt ice and snow.

Also, steel is not aluminum.

I think the point I was really trying to make was that the adhesive was "in addition to" traditional spot welding. I would not ride in any steel body/frame vehicle held together exclusively by adhesive.

The same statement would apply to aluminum alloy boats.

[yipster]

another fine car

The car has a hand-finished fiberglass body shell atop its aluminium extrusion and bonded frame that provides a rigid platform for the suspension

http://en.wikipedia.org/wiki/Lotus_Elise

[DanishBagger]

Aw, man, that car has been my favourite "toy car" ever since it came out!

[yipster]

now i do got the book in, "glare" is the name, also usable in other than aeronautic application the book mentions somewhere

http://en.wikipedia.org/wiki/Glare_(material)
http://www.tudelft.nl/live/pagina.js...63671d&lang=en
http://www.nlr.nl/id~4418/lang~en.pdf

[simon]

Yipster,

do you have an idea if 'GLARE's are of any reasonable use in boatbuilding? How are 'GLARE' panels assembled to build the whole structure?
Do you think that there is a possible low-tech approach for building glare panels that could improve fatigue resistance of aluminium?


Simon

[simon]

What about the approach to reinforce aluminium locally with composites to avoid fatigue cracking.

There is a description of a test made by the Australian Navy using carbon laminates to reinforce special areas.

http://adt.lib.rmit.edu.au/adt/uploa...ting_Essay.pdf

What about using local overlaminates or inserts in high stress areas to stiffen the structure in aluminium?

Or even replace parts of the structure with composite elements and use specialized joints for aluminium/composite instead of bolting them together.

There is document covering this:

www.vtt.fi/inf/pdf/tiedotteet/1997/T1862.pdf

Simon