How to anneal 5 micron aluminum foil ?

[Paul W]

I have been working on 1" ribbons for several months using 6.5 micron foil in the protypes. The problem with this foil is that I can't hold a close enough width tolerance (.004 or so) while slitting a 6' length.

I located a very small roll of 1" by 5 micron precision slit foil (exactly what I ultimately want to use) and have been hoarding it for the final ribbons...which were finished yesterday.

New problem. This foil is either treated differently, or a different alloy such that it seems very brittle and has a tendency to break during pleating.

Does anyone have any suggestions on how I might go about annealing the 5 micron foil?

[gengis]

I have heat treated AL, but much thicker than the one you are using, 1/8".

AL will be treated to zero temper after heating in oven at 700-800 F, after through heating, turn off oven. DO NOT open the oven door. Then let it cool in the oven.

AL will age and harden just being out in the air.

Hope this help.

[moray james]

If you are interested I would be happy to cryo treat your aluminum ribbon material no charge. Also I know of some folks who have found that a fine dimple patternis superior to the usual krinkle or fold technique most folks use. this makes the ribbon more rigid while keeping more of the conductor in the linear gap.
Send me an email if you are interested in the cryo offer. Best regards Moray James.

[gengis]

Would cryo treat the foil make it more brittle?

[moray james]

Cryo treatment would not make the aluminum brittle. Cryo treatment will improve the flex characteristics of the metal. I am sure that once you hear ribbons which hace been cryo treated you will not want to go back to untreated ribbons. Best regards Moray James.

[gengis]

Are we talking about the same thing?

When I think of cryo treatment, I am talking about a deep freeze, like a dip in Liquid Nitrogen.

It will make thing brittle.

[Variac]

Well yeah, its more brittle when its cold, but I think Morey means to return it to room temperature.....

[gengis]

The only way to anneal or heat treat (most of the time people wants harder, but can be softer too) is to heat the metal in a control fashion and let it cool, some cool in control fashion, some in atmospere.

I have never read or heard of cryo treating to anneal metal. Believe me, I have read the a lot of books on heat treating.

However, I can not argue as how good the sound after cryo treatment due to lack of experience.

[Variac]

And I don't knoww much about annealing, actually but that won't stop me from commenting!

When I think of cryo treatment, I am talking about a deep freeze, like a dip in Liquid Nitrogen.It will make thing brittle.

I agree that the only way I know of to anneal or harden aluminum is heating it.

Yet you gengis, are saying that cryo is going to harden it, without heat..

I don't see that Moray says that it will anneal the aluminum.
He says that it will improve the flex characteristics of the metal and sound better. I don't know what that means, and I don't know if it will or not. If anything I'm of the sceptical persuation

I also know that some metals are softened by slow cooling, some by fast quenching-right?

I thought that fast quenching hardened ferrous metals and softened non ferrous.

Anyway - why not try annealing,
If slow cooling doesn't work try fast....
then liquid nitrogen on a sample.

[Paul W]

Thanks guys. A little reading indicates that, depending on the alloy, a temperature between 500-900 degrees F is required. Heating is followed by, again depending on alloy, a slow cooldown, fast cooling, or instant/quenching.

Since I don't know which alloy I'm working with, I'm gonna sacrifice some foil to the oven gods!
Paul