Thermally conductive adhesive

[PaulM2]

I'm searching for a glue or caulking to secure absorbor plates which have separated from the pipes on a hot water solar panel. The pipes and plate collector are copper. I don't want to solder them because of the use of flux - corrosion. Thermal conduction is very important.The compound at this pdf link is available at the local hardware store. Are there any "chemists" or just someone here who can tell me from experience if this would work. Thanks very much. You guys have been alot of help.  http://www.permatex.com/MSDS_data/tds_files/81878.pdf

[DanG]

I've used the stuff to patch exhausts - it's just high temp silicone that will act more as an insulator than a conductor. There are plenty of non-corrosive solder-rosin paste mixes and rosins out there that work.

[maker of toys]

Solder it. you'll get FAR better heat transfer. Corrosion can be avoided by cleaning the joint afterward. Plus, a lot of the RTV (room temperature vulcanising) silicone compounds have acetic acid in them, and will cause corrosion themselves, particularly on aluminium and copper.

as 99Y has already said, there are low-corrosivity fluxes out there; one in particular that I like is a 'tinning' flux (has some solder in it) which has very good cleaning and wicking action. The active ingredient is water soluable and can be completely removed with soap, water and a sponge or rag. (or a good sluicing with a hose)

I'll post again later when I remember the name of the stuff. . .

if you're absolutely wedded to a silicone compound, use one with aluminium or copper particles in it for better heat transfer. . . .

-Dan

[maker of toys]

Ok, so I visited your permatex link, and if I were to use a silicone product for this application, I might very well choose that one.

BUT:

I still stand by the 'Solder it' comment I made earlier.

the solder I'd use is Oatey's H-20 95 product; it's a zinc chloride based, tinning,  water rinseable product.  it WILL induce corrosion if left on your workpiece and exposed to water and air, so DO rinse it off THOUROGHLY when you're finished with your repairs.  

I have used this product with good results on structural brass and copper; I have also used it on brass models, and can report that it does wash off well, with no corrosion on un-painted brass after 1 year. If you're particularly worried, a vinegar pickling followed by a baking-soda rinse and a water rinse should cure any residual reactivity.

I am not connected with Oatey in any way.

whatever method you choose, good luck!

-Dan

[ghurd]

Why not use a rosin core electrical solder?

Bare stuff stored in a basement I made 25 years ago still looks good.

Kester makes one that needs no rinse at all.

G-

[Jon Miller]

only a week ago someone asked the same question was it you ? link: http://www.fieldlines.com/story/2005/11/2/133249/210 At the time i to said soldering would be the best option anbd i stand by that.  You dont wat a silicon or a paste/glue in or around a solar tube yuk.  Just solder it and good luck

.

[DanG]

Thinking more of your original question, re: repairing and existing panel...

If you can't seperate the layers allowing safe torch use during a repair, I'm not sure of the best material to give a thermal bridge. Bonding may be a problem w/ all the heat cycles its exposed to, a combination of adhesive filler and mechanical clamps would be smart. Stainless steel automotive hose clamps come to mind.

I'd be tempted to use an epoxy w/ metal powder filler - if it is well mixed each metal particle would be encapsulated and you wouldn't have much worry over disimilar metal corrosion. Just offhand I'd say a good free source of metal powder would be an auto repair shop and get some of the metal filings from when they true brake discs and such...

[coldspot]

If anybody cares still-

I would use a product called "Muffler cement"

I used to sell it @ my last job, I can't get myself to recomend them yet! (&^$@!#%&*&&^%#@) that I worked for! Instead of screwing me out of X-mas Bonus

I got fired for stupid reason, new owner is a rich kid brat!

They didn't make the stuff but I did sell a lot of it, mostly thru the website I mantained for them.

If someone really wanted some I know where to buy it, (were they did, also a place I worked a lifetime ago)!

Best to do a web search for it.

PS: don't buy it from ppp!

l8r