Gap filling at Liquid Nitrogen Temperatures

[MAC3382]

Hello, All:

I am trying to fill a cylindrical gap between a magnet array and an Aluminum tube. The magnet array is ~ 3.940" OD x 6" axial length. It fits within a 6061-T6 Al tube with an ID of ~ 4.000". (The device will have flanges at each end.) The array is assembled at room temperature with an acrylic adhesive. The magnets in the array are mutually repelling. At LN temperatures I am concerned the array will work-apart and the magnets will move out of position, effectively distorting the desired field distribution. Our original intent was to locate, a yet to be determined solid substance, in the resulting gap between the array and outer tube to ensure the magnets could not move. Now there has been a discussion to use a gap filling media. There are adhesives, but they are quite expensive and we require no adhesive strength. (Also no thermal properties, electrical properties, etc. are required) We only need the gap filling material to retain its shape (mostly) and take of space so the magnets have no place to move to.

Without much practical knowledge we thought of expanding foam, silicon caulk, etc.

Would you please offer any advice regarding common materials that could be used to fill the gap at LN temperatures? (viscosity is not an issue.)

Thank you,

Mac

 

[MintJulep]

A Google search for 'cryogenic potting compound' turns up a few likely candidates.

 

[Compositepro]

You might consider pouring a low melting point metal alloy into the gap, or using small diameter stainless steel tubes pressed into the gap so they act as centering springs.